netbox/netbox/dcim/forms.py

from __future__ import unicode_literals

import re

from django import forms
from django.contrib.auth.models import User
from django.contrib.postgres.forms.array import SimpleArrayField
from django.db.models import Count, Q
from mptt.forms import TreeNodeChoiceField
from timezone_field import TimeZoneFormField

from extras.forms import CustomFieldForm, CustomFieldBulkEditForm, CustomFieldFilterForm
from ipam.models import IPAddress, VLAN, VLANGroup
from tenancy.forms import TenancyForm
from tenancy.models import Tenant
from utilities.forms import (
    APISelect, APISelectMultiple, add_blank_choice, ArrayFieldSelectMultiple, BootstrapMixin, BulkEditForm,
    BulkEditNullBooleanSelect, ChainedFieldsMixin, ChainedModelChoiceField, ChainedModelMultipleChoiceField,
    CommentField, ComponentForm, ConfirmationForm, CSVChoiceField, ExpandableNameField, FilterChoiceField,
    FlexibleModelChoiceField, Livesearch, SelectWithDisabled, SmallTextarea, SlugField,
    FilterTreeNodeMultipleChoiceField,
)
from virtualization.models import Cluster
from .constants import (
    CONNECTION_STATUS_CHOICES, CONNECTION_STATUS_CONNECTED, DEVICE_STATUS_CHOICES, IFACE_FF_CHOICES, IFACE_FF_LAG,
    IFACE_MODE_ACCESS, IFACE_MODE_CHOICES, IFACE_MODE_TAGGED_ALL, IFACE_ORDERING_CHOICES, RACK_FACE_CHOICES,
    RACK_TYPE_CHOICES, RACK_WIDTH_CHOICES, RACK_WIDTH_19IN, RACK_WIDTH_23IN, SITE_STATUS_CHOICES, SUBDEVICE_ROLE_CHILD,
    SUBDEVICE_ROLE_PARENT, SUBDEVICE_ROLE_CHOICES,
)
from .formfields import MACAddressFormField
from .models import (
    DeviceBay, DeviceBayTemplate, ConsolePort, ConsolePortTemplate, ConsoleServerPort, ConsoleServerPortTemplate,
    Device, DeviceRole, DeviceType, Interface, InterfaceConnection, InterfaceTemplate, Manufacturer, InventoryItem,
    Platform, PowerOutlet, PowerOutletTemplate, PowerPort, PowerPortTemplate, Rack, RackGroup, RackReservation,
    RackRole, Region, Site, VirtualChassis
)

DEVICE_BY_PK_RE = '{\d+\}'


def get_device_by_name_or_pk(name):
    """
    Attempt to retrieve a device by either its name or primary key ('{pk}').
    """
    if re.match(DEVICE_BY_PK_RE, name):
        pk = name.strip('{}')
        device = Device.objects.get(pk=pk)
    else:
        device = Device.objects.get(name=name)
    return device


class BulkRenameForm(forms.Form):
    """
    An extendable form to be used for renaming device components in bulk.
    """
    find = forms.CharField()
    replace = forms.CharField()


#
# Regions
#

class RegionForm(BootstrapMixin, forms.ModelForm):
    slug = SlugField()

    class Meta:
        model = Region
        fields = ['parent', 'name', 'slug']


class RegionCSVForm(forms.ModelForm):
    parent = forms.ModelChoiceField(
        queryset=Region.objects.all(),
        required=False,
        to_field_name='name',
        help_text='Name of parent region',
        error_messages={
            'invalid_choice': 'Region not found.',
        }
    )

    class Meta:
        model = Region
        fields = Region.csv_headers
        help_texts = {
            'name': 'Region name',
            'slug': 'URL-friendly slug',
        }


class RegionFilterForm(BootstrapMixin, forms.Form):
    model = Site
    q = forms.CharField(required=False, label='Search')


#
# Sites
#

class SiteForm(BootstrapMixin, TenancyForm, CustomFieldForm):
    region = TreeNodeChoiceField(queryset=Region.objects.all(), required=False)
    slug = SlugField()
    comments = CommentField()

    class Meta:
        model = Site
        fields = [
            'name', 'slug', 'status', 'region', 'tenant_group', 'tenant', 'facility', 'asn', 'description',
            'physical_address', 'shipping_address', 'contact_name', 'contact_phone', 'contact_email', 'time_zone',
            'comments',
        ]
        widgets = {
            'physical_address': SmallTextarea(attrs={'rows': 3}),
            'shipping_address': SmallTextarea(attrs={'rows': 3}),
        }
        help_texts = {
            'name': "Full name of the site",
            'facility': "Data center provider and facility (e.g. Equinix NY7)",
            'asn': "BGP autonomous system number",
            'physical_address': "Physical location of the building (e.g. for GPS)",
            'shipping_address': "If different from the physical address"
        }


class SiteCSVForm(forms.ModelForm):
    status = CSVChoiceField(
        choices=DEVICE_STATUS_CHOICES,
        required=False,
        help_text='Operational status'
    )
    region = forms.ModelChoiceField(
        queryset=Region.objects.all(),
        required=False,
        to_field_name='name',
        help_text='Name of assigned region',
        error_messages={
            'invalid_choice': 'Region not found.',
        }
    )
    tenant = forms.ModelChoiceField(
        queryset=Tenant.objects.all(),
        required=False,
        to_field_name='name',
        help_text='Name of assigned tenant',
        error_messages={
            'invalid_choice': 'Tenant not found.',
        }
    )

    class Meta:
        model = Site
        fields = Site.csv_headers
        help_texts = {
            'name': 'Site name',
            'slug': 'URL-friendly slug',
            'asn': '32-bit autonomous system number',
        }


class SiteBulkEditForm(BootstrapMixin, CustomFieldBulkEditForm):
    pk = forms.ModelMultipleChoiceField(queryset=Site.objects.all(), widget=forms.MultipleHiddenInput)
    status = forms.ChoiceField(choices=add_blank_choice(SITE_STATUS_CHOICES), required=False, initial='')
    region = TreeNodeChoiceField(queryset=Region.objects.all(), required=False)
    tenant = forms.ModelChoiceField(queryset=Tenant.objects.all(), required=False)
    asn = forms.IntegerField(min_value=1, max_value=4294967295, required=False, label='ASN')
    description = forms.CharField(max_length=100, required=False)
    time_zone = TimeZoneFormField(required=False)

    class Meta:
        nullable_fields = ['region', 'tenant', 'asn', 'description', 'time_zone']


def site_status_choices():
    status_counts = {}
    for status in Site.objects.values('status').annotate(count=Count('status')).order_by('status'):
        status_counts[status['status']] = status['count']
    return [(s[0], '{} ({})'.format(s[1], status_counts.get(s[0], 0))) for s in SITE_STATUS_CHOICES]


class SiteFilterForm(BootstrapMixin, CustomFieldFilterForm):
    model = Site
    q = forms.CharField(required=False, label='Search')
    status = forms.MultipleChoiceField(choices=site_status_choices, required=False)
    region = FilterTreeNodeMultipleChoiceField(
        queryset=Region.objects.annotate(filter_count=Count('sites')),
        to_field_name='slug',
        required=False,
    )
    tenant = FilterChoiceField(
        queryset=Tenant.objects.annotate(filter_count=Count('sites')),
        to_field_name='slug',
        null_label='-- None --'
    )


#
# Rack groups
#

class RackGroupForm(BootstrapMixin, forms.ModelForm):
    slug = SlugField()

    class Meta:
        model = RackGroup
        fields = ['site', 'name', 'slug']


class RackGroupCSVForm(forms.ModelForm):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        to_field_name='name',
        help_text='Name of parent site',
        error_messages={
            'invalid_choice': 'Site not found.',
        }
    )

    class Meta:
        model = RackGroup
        fields = RackGroup.csv_headers
        help_texts = {
            'name': 'Name of rack group',
            'slug': 'URL-friendly slug',
        }


class RackGroupFilterForm(BootstrapMixin, forms.Form):
    site = FilterChoiceField(queryset=Site.objects.annotate(filter_count=Count('rack_groups')), to_field_name='slug')


#
# Rack roles
#

class RackRoleForm(BootstrapMixin, forms.ModelForm):
    slug = SlugField()

    class Meta:
        model = RackRole
        fields = ['name', 'slug', 'color']


class RackRoleCSVForm(forms.ModelForm):
    slug = SlugField()

    class Meta:
        model = RackRole
        fields = RackRole.csv_headers
        help_texts = {
            'name': 'Name of rack role',
            'color': 'RGB color in hexadecimal (e.g. 00ff00)'
        }


#
# Racks
#

class RackForm(BootstrapMixin, TenancyForm, CustomFieldForm):
    group = ChainedModelChoiceField(
        queryset=RackGroup.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        required=False,
        widget=APISelect(
            api_url='/api/dcim/rack-groups/?site_id={{site}}',
        )
    )
    comments = CommentField()

    class Meta:
        model = Rack
        fields = [
            'site', 'group', 'name', 'facility_id', 'tenant_group', 'tenant', 'role', 'serial', 'type', 'width',
            'u_height', 'desc_units', 'comments',
        ]
        help_texts = {
            'site': "The site at which the rack exists",
            'name': "Organizational rack name",
            'facility_id': "The unique rack ID assigned by the facility",
            'u_height': "Height in rack units",
        }
        widgets = {
            'site': forms.Select(attrs={'filter-for': 'group'}),
        }


class RackCSVForm(forms.ModelForm):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        to_field_name='name',
        help_text='Name of parent site',
        error_messages={
            'invalid_choice': 'Site not found.',
        }
    )
    group_name = forms.CharField(
        help_text='Name of rack group',
        required=False
    )
    tenant = forms.ModelChoiceField(
        queryset=Tenant.objects.all(),
        required=False,
        to_field_name='name',
        help_text='Name of assigned tenant',
        error_messages={
            'invalid_choice': 'Tenant not found.',
        }
    )
    role = forms.ModelChoiceField(
        queryset=RackRole.objects.all(),
        required=False,
        to_field_name='name',
        help_text='Name of assigned role',
        error_messages={
            'invalid_choice': 'Role not found.',
        }
    )
    type = CSVChoiceField(
        choices=RACK_TYPE_CHOICES,
        required=False,
        help_text='Rack type'
    )
    width = forms.ChoiceField(
        choices=(
            (RACK_WIDTH_19IN, '19'),
            (RACK_WIDTH_23IN, '23'),
        ),
        help_text='Rail-to-rail width (in inches)'
    )

    class Meta:
        model = Rack
        fields = Rack.csv_headers
        help_texts = {
            'name': 'Rack name',
            'u_height': 'Height in rack units',
        }

    def clean(self):

        super(RackCSVForm, self).clean()

        site = self.cleaned_data.get('site')
        group_name = self.cleaned_data.get('group_name')

        # Validate rack group
        if group_name:
            try:
                self.instance.group = RackGroup.objects.get(site=site, name=group_name)
            except RackGroup.DoesNotExist:
                raise forms.ValidationError("Rack group {} not found for site {}".format(group_name, site))


class RackBulkEditForm(BootstrapMixin, CustomFieldBulkEditForm):
    pk = forms.ModelMultipleChoiceField(queryset=Rack.objects.all(), widget=forms.MultipleHiddenInput)
    site = forms.ModelChoiceField(queryset=Site.objects.all(), required=False, label='Site')
    group = forms.ModelChoiceField(queryset=RackGroup.objects.all(), required=False, label='Group')
    tenant = forms.ModelChoiceField(queryset=Tenant.objects.all(), required=False)
    role = forms.ModelChoiceField(queryset=RackRole.objects.all(), required=False)
    serial = forms.CharField(max_length=50, required=False, label='Serial Number')
    type = forms.ChoiceField(choices=add_blank_choice(RACK_TYPE_CHOICES), required=False, label='Type')
    width = forms.ChoiceField(choices=add_blank_choice(RACK_WIDTH_CHOICES), required=False, label='Width')
    u_height = forms.IntegerField(required=False, label='Height (U)')
    desc_units = forms.NullBooleanField(required=False, widget=BulkEditNullBooleanSelect, label='Descending units')
    comments = CommentField(widget=SmallTextarea)

    class Meta:
        nullable_fields = ['group', 'tenant', 'role', 'serial', 'comments']


class RackFilterForm(BootstrapMixin, CustomFieldFilterForm):
    model = Rack
    q = forms.CharField(required=False, label='Search')
    site = FilterChoiceField(
        queryset=Site.objects.annotate(filter_count=Count('racks')),
        to_field_name='slug'
    )
    group_id = FilterChoiceField(
        queryset=RackGroup.objects.select_related('site').annotate(filter_count=Count('racks')),
        label='Rack group',
        null_label='-- None --'
    )
    tenant = FilterChoiceField(
        queryset=Tenant.objects.annotate(filter_count=Count('racks')),
        to_field_name='slug',
        null_label='-- None --'
    )
    role = FilterChoiceField(
        queryset=RackRole.objects.annotate(filter_count=Count('racks')),
        to_field_name='slug',
        null_label='-- None --'
    )


#
# Rack reservations
#

class RackReservationForm(BootstrapMixin, TenancyForm, forms.ModelForm):
    units = SimpleArrayField(forms.IntegerField(), widget=ArrayFieldSelectMultiple(attrs={'size': 10}))
    user = forms.ModelChoiceField(queryset=User.objects.order_by('username'))

    class Meta:
        model = RackReservation
        fields = ['units', 'user', 'tenant_group', 'tenant', 'description']

    def __init__(self, *args, **kwargs):

        super(RackReservationForm, self).__init__(*args, **kwargs)

        # Populate rack unit choices
        self.fields['units'].widget.choices = self._get_unit_choices()

    def _get_unit_choices(self):
        rack = self.instance.rack
        reserved_units = []
        for resv in rack.reservations.exclude(pk=self.instance.pk):
            for u in resv.units:
                reserved_units.append(u)
        unit_choices = [(u, {'label': str(u), 'disabled': u in reserved_units}) for u in rack.units]
        return unit_choices


class RackReservationFilterForm(BootstrapMixin, forms.Form):
    q = forms.CharField(required=False, label='Search')
    site = FilterChoiceField(
        queryset=Site.objects.annotate(filter_count=Count('racks__reservations')),
        to_field_name='slug'
    )
    group_id = FilterChoiceField(
        queryset=RackGroup.objects.select_related('site').annotate(filter_count=Count('racks__reservations')),
        label='Rack group',
        null_label='-- None --'
    )
    tenant = FilterChoiceField(
        queryset=Tenant.objects.annotate(filter_count=Count('rackreservations')),
        to_field_name='slug',
        null_label='-- None --'
    )


class RackReservationBulkEditForm(BootstrapMixin, BulkEditForm):
    pk = forms.ModelMultipleChoiceField(queryset=RackReservation.objects.all(), widget=forms.MultipleHiddenInput)
    user = forms.ModelChoiceField(queryset=User.objects.order_by('username'), required=False)
    tenant = forms.ModelChoiceField(queryset=Tenant.objects.all(), required=False)
    description = forms.CharField(max_length=100, required=False)

    class Meta:
        nullable_fields = []


#
# Manufacturers
#

class ManufacturerForm(BootstrapMixin, forms.ModelForm):
    slug = SlugField()

    class Meta:
        model = Manufacturer
        fields = ['name', 'slug']


class ManufacturerCSVForm(forms.ModelForm):
    class Meta:
        model = Manufacturer
        fields = Manufacturer.csv_headers
        help_texts = {
            'name': 'Manufacturer name',
            'slug': 'URL-friendly slug',
        }


#
# Device types
#

class DeviceTypeForm(BootstrapMixin, CustomFieldForm):
    slug = SlugField(slug_source='model')

    class Meta:
        model = DeviceType
        fields = ['manufacturer', 'model', 'slug', 'part_number', 'u_height', 'is_full_depth', 'is_console_server',
                  'is_pdu', 'is_network_device', 'subdevice_role', 'interface_ordering', 'comments']
        labels = {
            'interface_ordering': 'Order interfaces by',
        }


class DeviceTypeCSVForm(forms.ModelForm):
    manufacturer = forms.ModelChoiceField(
        queryset=Manufacturer.objects.all(),
        required=True,
        to_field_name='name',
        help_text='Manufacturer name',
        error_messages={
            'invalid_choice': 'Manufacturer not found.',
        }
    )
    subdevice_role = CSVChoiceField(
        choices=SUBDEVICE_ROLE_CHOICES,
        required=False,
        help_text='Parent/child status'
    )
    interface_ordering = CSVChoiceField(
        choices=IFACE_ORDERING_CHOICES,
        required=False,
        help_text='Interface ordering'
    )

    class Meta:
        model = DeviceType
        fields = DeviceType.csv_headers
        help_texts = {
            'model': 'Model name',
            'slug': 'URL-friendly slug',
        }


class DeviceTypeBulkEditForm(BootstrapMixin, CustomFieldBulkEditForm):
    pk = forms.ModelMultipleChoiceField(queryset=DeviceType.objects.all(), widget=forms.MultipleHiddenInput)
    manufacturer = forms.ModelChoiceField(queryset=Manufacturer.objects.all(), required=False)
    u_height = forms.IntegerField(min_value=1, required=False)
    is_full_depth = forms.NullBooleanField(required=False, widget=BulkEditNullBooleanSelect, label='Is full depth')
    interface_ordering = forms.ChoiceField(choices=add_blank_choice(IFACE_ORDERING_CHOICES), required=False)
    is_console_server = forms.NullBooleanField(
        required=False, widget=BulkEditNullBooleanSelect, label='Is a console server'
    )
    is_pdu = forms.NullBooleanField(required=False, widget=BulkEditNullBooleanSelect, label='Is a PDU')
    is_network_device = forms.NullBooleanField(
        required=False, widget=BulkEditNullBooleanSelect, label='Is a network device'
    )

    class Meta:
        nullable_fields = []


class DeviceTypeFilterForm(BootstrapMixin, CustomFieldFilterForm):
    model = DeviceType
    q = forms.CharField(required=False, label='Search')
    manufacturer = FilterChoiceField(
        queryset=Manufacturer.objects.annotate(filter_count=Count('device_types')),
        to_field_name='slug'
    )
    is_console_server = forms.BooleanField(
        required=False, label='Is a console server', widget=forms.CheckboxInput(attrs={'value': 'True'}))
    is_pdu = forms.BooleanField(
        required=False, label='Is a PDU', widget=forms.CheckboxInput(attrs={'value': 'True'})
    )
    is_network_device = forms.BooleanField(
        required=False, label='Is a network device', widget=forms.CheckboxInput(attrs={'value': 'True'})
    )
    subdevice_role = forms.NullBooleanField(
        required=False, label='Subdevice role', widget=forms.Select(choices=(
            ('', '---------'),
            (SUBDEVICE_ROLE_PARENT, 'Parent'),
            (SUBDEVICE_ROLE_CHILD, 'Child'),
        ))
    )


#
# Device component templates
#

class ConsolePortTemplateForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = ConsolePortTemplate
        fields = ['device_type', 'name']
        widgets = {
            'device_type': forms.HiddenInput(),
        }


class ConsolePortTemplateCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


class ConsoleServerPortTemplateForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = ConsoleServerPortTemplate
        fields = ['device_type', 'name']
        widgets = {
            'device_type': forms.HiddenInput(),
        }


class ConsoleServerPortTemplateCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


class PowerPortTemplateForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = PowerPortTemplate
        fields = ['device_type', 'name']
        widgets = {
            'device_type': forms.HiddenInput(),
        }


class PowerPortTemplateCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


class PowerOutletTemplateForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = PowerOutletTemplate
        fields = ['device_type', 'name']
        widgets = {
            'device_type': forms.HiddenInput(),
        }


class PowerOutletTemplateCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


class InterfaceTemplateForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = InterfaceTemplate
        fields = ['device_type', 'name', 'form_factor', 'mgmt_only']
        widgets = {
            'device_type': forms.HiddenInput(),
        }


class InterfaceTemplateCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')
    form_factor = forms.ChoiceField(choices=IFACE_FF_CHOICES)
    mgmt_only = forms.BooleanField(required=False, label='OOB Management')


class InterfaceTemplateBulkEditForm(BootstrapMixin, BulkEditForm):
    pk = forms.ModelMultipleChoiceField(queryset=InterfaceTemplate.objects.all(), widget=forms.MultipleHiddenInput)
    form_factor = forms.ChoiceField(choices=add_blank_choice(IFACE_FF_CHOICES), required=False)
    mgmt_only = forms.NullBooleanField(required=False, widget=BulkEditNullBooleanSelect, label='Management only')

    class Meta:
        nullable_fields = []


class DeviceBayTemplateForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = DeviceBayTemplate
        fields = ['device_type', 'name']
        widgets = {
            'device_type': forms.HiddenInput(),
        }


class DeviceBayTemplateCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


#
# Device roles
#

class DeviceRoleForm(BootstrapMixin, forms.ModelForm):
    slug = SlugField()

    class Meta:
        model = DeviceRole
        fields = ['name', 'slug', 'color', 'vm_role']


class DeviceRoleCSVForm(forms.ModelForm):
    slug = SlugField()

    class Meta:
        model = DeviceRole
        fields = DeviceRole.csv_headers
        help_texts = {
            'name': 'Name of device role',
            'color': 'RGB color in hexadecimal (e.g. 00ff00)'
        }


#
# Platforms
#

class PlatformForm(BootstrapMixin, forms.ModelForm):
    slug = SlugField()

    class Meta:
        model = Platform
        fields = ['name', 'slug', 'manufacturer', 'napalm_driver', 'rpc_client']


class PlatformCSVForm(forms.ModelForm):
    slug = SlugField()

    class Meta:
        model = Platform
        fields = Platform.csv_headers
        help_texts = {
            'name': 'Platform name',
            'manufacturer': 'Manufacturer name',
        }


#
# Devices
#

class DeviceForm(BootstrapMixin, TenancyForm, CustomFieldForm):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        widget=forms.Select(
            attrs={'filter-for': 'rack'}
        )
    )
    rack = ChainedModelChoiceField(
        queryset=Rack.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        required=False,
        widget=APISelect(
            api_url='/api/dcim/racks/?site_id={{site}}',
            display_field='display_name',
            attrs={'filter-for': 'position'}
        )
    )
    position = forms.TypedChoiceField(
        required=False,
        empty_value=None,
        help_text="The lowest-numbered unit occupied by the device",
        widget=APISelect(
            api_url='/api/dcim/racks/{{rack}}/units/?face={{face}}',
            disabled_indicator='device'
        )
    )
    manufacturer = forms.ModelChoiceField(
        queryset=Manufacturer.objects.all(),
        widget=forms.Select(
            attrs={'filter-for': 'device_type'}
        )
    )
    device_type = ChainedModelChoiceField(
        queryset=DeviceType.objects.all(),
        chains=(
            ('manufacturer', 'manufacturer'),
        ),
        label='Device type',
        widget=APISelect(
            api_url='/api/dcim/device-types/?manufacturer_id={{manufacturer}}',
            display_field='model'
        )
    )
    comments = CommentField()

    class Meta:
        model = Device
        fields = [
            'name', 'device_role', 'device_type', 'serial', 'asset_tag', 'site', 'rack', 'position', 'face', 'status',
            'platform', 'primary_ip4', 'primary_ip6', 'tenant_group', 'tenant', 'comments',
        ]
        help_texts = {
            'device_role': "The function this device serves",
            'serial': "Chassis serial number",
        }
        widgets = {
            'face': forms.Select(attrs={'filter-for': 'position'}),
        }

    def __init__(self, *args, **kwargs):

        # Initialize helper selectors
        instance = kwargs.get('instance')
        # Using hasattr() instead of "is not None" to avoid RelatedObjectDoesNotExist on required field
        if instance and hasattr(instance, 'device_type'):
            initial = kwargs.get('initial', {}).copy()
            initial['manufacturer'] = instance.device_type.manufacturer
            kwargs['initial'] = initial

        super(DeviceForm, self).__init__(*args, **kwargs)

        if self.instance.pk:

            # Compile list of choices for primary IPv4 and IPv6 addresses
            for family in [4, 6]:
                ip_choices = [(None, '---------')]

                # Gather PKs of all interfaces belonging to this Device or a peer VirtualChassis member
                interface_ids = self.instance.vc_interfaces.values('pk')

                # Collect interface IPs
                interface_ips = IPAddress.objects.select_related('interface').filter(
                    family=family, interface_id__in=interface_ids
                )
                if interface_ips:
                    ip_list = [(ip.id, '{} ({})'.format(ip.address, ip.interface)) for ip in interface_ips]
                    ip_choices.append(('Interface IPs', ip_list))
                # Collect NAT IPs
                nat_ips = IPAddress.objects.select_related('nat_inside').filter(
                    family=family, nat_inside__interface__in=interface_ids
                )
                if nat_ips:
                    ip_list = [(ip.id, '{} ({})'.format(ip.address, ip.nat_inside.address)) for ip in nat_ips]
                    ip_choices.append(('NAT IPs', ip_list))
                self.fields['primary_ip{}'.format(family)].choices = ip_choices

            # If editing an existing device, exclude it from the list of occupied rack units. This ensures that a device
            # can be flipped from one face to another.
            self.fields['position'].widget.attrs['api-url'] += '&exclude={}'.format(self.instance.pk)

            # Limit platform by manufacturer
            self.fields['platform'].queryset = Platform.objects.filter(
                Q(manufacturer__isnull=True) | Q(manufacturer=self.instance.device_type.manufacturer)
            )

        else:

            # An object that doesn't exist yet can't have any IPs assigned to it
            self.fields['primary_ip4'].choices = []
            self.fields['primary_ip4'].widget.attrs['readonly'] = True
            self.fields['primary_ip6'].choices = []
            self.fields['primary_ip6'].widget.attrs['readonly'] = True

        # Rack position
        pk = self.instance.pk if self.instance.pk else None
        try:
            if self.is_bound and self.data.get('rack') and str(self.data.get('face')):
                position_choices = Rack.objects.get(pk=self.data['rack']) \
                    .get_rack_units(face=self.data.get('face'), exclude=pk)
            elif self.initial.get('rack') and str(self.initial.get('face')):
                position_choices = Rack.objects.get(pk=self.initial['rack']) \
                    .get_rack_units(face=self.initial.get('face'), exclude=pk)
            else:
                position_choices = []
        except Rack.DoesNotExist:
            position_choices = []
        self.fields['position'].choices = [('', '---------')] + [
            (p['id'], {
                'label': p['name'],
                'disabled': bool(p['device'] and p['id'] != self.initial.get('position')),
            }) for p in position_choices
        ]

        # Disable rack assignment if this is a child device installed in a parent device
        if pk and self.instance.device_type.is_child_device and hasattr(self.instance, 'parent_bay'):
            self.fields['site'].disabled = True
            self.fields['rack'].disabled = True
            self.initial['site'] = self.instance.parent_bay.device.site_id
            self.initial['rack'] = self.instance.parent_bay.device.rack_id


class BaseDeviceCSVForm(forms.ModelForm):
    device_role = forms.ModelChoiceField(
        queryset=DeviceRole.objects.all(),
        to_field_name='name',
        help_text='Name of assigned role',
        error_messages={
            'invalid_choice': 'Invalid device role.',
        }
    )
    tenant = forms.ModelChoiceField(
        queryset=Tenant.objects.all(),
        required=False,
        to_field_name='name',
        help_text='Name of assigned tenant',
        error_messages={
            'invalid_choice': 'Tenant not found.',
        }
    )
    manufacturer = forms.ModelChoiceField(
        queryset=Manufacturer.objects.all(),
        to_field_name='name',
        help_text='Device type manufacturer',
        error_messages={
            'invalid_choice': 'Invalid manufacturer.',
        }
    )
    model_name = forms.CharField(
        help_text='Device type model name'
    )
    platform = forms.ModelChoiceField(
        queryset=Platform.objects.all(),
        required=False,
        to_field_name='name',
        help_text='Name of assigned platform',
        error_messages={
            'invalid_choice': 'Invalid platform.',
        }
    )
    status = CSVChoiceField(
        choices=DEVICE_STATUS_CHOICES,
        help_text='Operational status'
    )

    class Meta:
        fields = []
        model = Device
        help_texts = {
            'name': 'Device name',
        }

    def clean(self):

        super(BaseDeviceCSVForm, self).clean()

        manufacturer = self.cleaned_data.get('manufacturer')
        model_name = self.cleaned_data.get('model_name')

        # Validate device type
        if manufacturer and model_name:
            try:
                self.instance.device_type = DeviceType.objects.get(manufacturer=manufacturer, model=model_name)
            except DeviceType.DoesNotExist:
                raise forms.ValidationError("Device type {} {} not found".format(manufacturer, model_name))


class DeviceCSVForm(BaseDeviceCSVForm):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        to_field_name='name',
        help_text='Name of parent site',
        error_messages={
            'invalid_choice': 'Invalid site name.',
        }
    )
    rack_group = forms.CharField(
        required=False,
        help_text='Parent rack\'s group (if any)'
    )
    rack_name = forms.CharField(
        required=False,
        help_text='Name of parent rack'
    )
    face = CSVChoiceField(
        choices=RACK_FACE_CHOICES,
        required=False,
        help_text='Mounted rack face'
    )
    cluster = forms.ModelChoiceField(
        queryset=Cluster.objects.all(),
        to_field_name='name',
        required=False,
        help_text='Virtualization cluster',
        error_messages={
            'invalid_choice': 'Invalid cluster name.',
        }
    )

    class Meta(BaseDeviceCSVForm.Meta):
        fields = [
            'name', 'device_role', 'tenant', 'manufacturer', 'model_name', 'platform', 'serial', 'asset_tag', 'status',
            'site', 'rack_group', 'rack_name', 'position', 'face', 'cluster', 'comments',
        ]

    def clean(self):

        super(DeviceCSVForm, self).clean()

        site = self.cleaned_data.get('site')
        rack_group = self.cleaned_data.get('rack_group')
        rack_name = self.cleaned_data.get('rack_name')

        # Validate rack
        if site and rack_group and rack_name:
            try:
                self.instance.rack = Rack.objects.get(site=site, group__name=rack_group, name=rack_name)
            except Rack.DoesNotExist:
                raise forms.ValidationError("Rack {} not found in site {} group {}".format(rack_name, site, rack_group))
        elif site and rack_name:
            try:
                self.instance.rack = Rack.objects.get(site=site, group__isnull=True, name=rack_name)
            except Rack.DoesNotExist:
                raise forms.ValidationError("Rack {} not found in site {} (no group)".format(rack_name, site))


class ChildDeviceCSVForm(BaseDeviceCSVForm):
    parent = FlexibleModelChoiceField(
        queryset=Device.objects.all(),
        to_field_name='name',
        help_text='Name or ID of parent device',
        error_messages={
            'invalid_choice': 'Parent device not found.',
        }
    )
    device_bay_name = forms.CharField(
        help_text='Name of device bay',
    )
    cluster = forms.ModelChoiceField(
        queryset=Cluster.objects.all(),
        to_field_name='name',
        required=False,
        help_text='Virtualization cluster',
        error_messages={
            'invalid_choice': 'Invalid cluster name.',
        }
    )

    class Meta(BaseDeviceCSVForm.Meta):
        fields = [
            'name', 'device_role', 'tenant', 'manufacturer', 'model_name', 'platform', 'serial', 'asset_tag', 'status',
            'parent', 'device_bay_name', 'cluster', 'comments',
        ]

    def clean(self):

        super(ChildDeviceCSVForm, self).clean()

        parent = self.cleaned_data.get('parent')
        device_bay_name = self.cleaned_data.get('device_bay_name')

        # Validate device bay
        if parent and device_bay_name:
            try:
                self.instance.parent_bay = DeviceBay.objects.get(device=parent, name=device_bay_name)
                # Inherit site and rack from parent device
                self.instance.site = parent.site
                self.instance.rack = parent.rack
            except DeviceBay.DoesNotExist:
                raise forms.ValidationError("Parent device/bay ({} {}) not found".format(parent, device_bay_name))


class DeviceBulkEditForm(BootstrapMixin, CustomFieldBulkEditForm):
    pk = forms.ModelMultipleChoiceField(queryset=Device.objects.all(), widget=forms.MultipleHiddenInput)
    device_type = forms.ModelChoiceField(queryset=DeviceType.objects.all(), required=False, label='Type')
    device_role = forms.ModelChoiceField(queryset=DeviceRole.objects.all(), required=False, label='Role')
    tenant = forms.ModelChoiceField(queryset=Tenant.objects.all(), required=False)
    platform = forms.ModelChoiceField(queryset=Platform.objects.all(), required=False)
    status = forms.ChoiceField(choices=add_blank_choice(DEVICE_STATUS_CHOICES), required=False, initial='')
    serial = forms.CharField(max_length=50, required=False, label='Serial Number')

    class Meta:
        nullable_fields = ['tenant', 'platform', 'serial']


def device_status_choices():
    status_counts = {}
    for status in Device.objects.values('status').annotate(count=Count('status')).order_by('status'):
        status_counts[status['status']] = status['count']
    return [(s[0], '{} ({})'.format(s[1], status_counts.get(s[0], 0))) for s in DEVICE_STATUS_CHOICES]


class DeviceFilterForm(BootstrapMixin, CustomFieldFilterForm):
    model = Device
    q = forms.CharField(required=False, label='Search')
    site = FilterChoiceField(
        queryset=Site.objects.annotate(filter_count=Count('devices')),
        to_field_name='slug',
    )
    rack_group_id = FilterChoiceField(
        queryset=RackGroup.objects.select_related('site').annotate(filter_count=Count('racks__devices')),
        label='Rack group',
    )
    rack_id = FilterChoiceField(
        queryset=Rack.objects.annotate(filter_count=Count('devices')),
        label='Rack',
        null_label='-- None --',
    )
    role = FilterChoiceField(
        queryset=DeviceRole.objects.annotate(filter_count=Count('devices')),
        to_field_name='slug',
    )
    tenant = FilterChoiceField(
        queryset=Tenant.objects.annotate(filter_count=Count('devices')),
        to_field_name='slug',
        null_label='-- None --',
    )
    manufacturer_id = FilterChoiceField(queryset=Manufacturer.objects.all(), label='Manufacturer')
    device_type_id = FilterChoiceField(
        queryset=DeviceType.objects.select_related('manufacturer').order_by('model').annotate(
            filter_count=Count('instances'),
        ),
        label='Model',
    )
    platform = FilterChoiceField(
        queryset=Platform.objects.annotate(filter_count=Count('devices')),
        to_field_name='slug',
        null_label='-- None --',
    )
    status = forms.MultipleChoiceField(choices=device_status_choices, required=False)
    mac_address = forms.CharField(required=False, label='MAC address')


#
# Bulk device component creation
#

class DeviceBulkAddComponentForm(BootstrapMixin, forms.Form):
    pk = forms.ModelMultipleChoiceField(queryset=Device.objects.all(), widget=forms.MultipleHiddenInput)
    name_pattern = ExpandableNameField(label='Name')


class DeviceBulkAddInterfaceForm(DeviceBulkAddComponentForm):
    form_factor = forms.ChoiceField(choices=IFACE_FF_CHOICES)
    enabled = forms.BooleanField(required=False, initial=True)
    mtu = forms.IntegerField(required=False, min_value=1, max_value=32767, label='MTU')
    mgmt_only = forms.BooleanField(required=False, label='OOB Management')
    description = forms.CharField(max_length=100, required=False)


#
# Console ports
#

class ConsolePortForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = ConsolePort
        fields = ['device', 'name']
        widgets = {
            'device': forms.HiddenInput(),
        }


class ConsolePortCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


class ConsoleConnectionCSVForm(forms.ModelForm):
    console_server = FlexibleModelChoiceField(
        queryset=Device.objects.filter(device_type__is_console_server=True),
        to_field_name='name',
        help_text='Console server name or ID',
        error_messages={
            'invalid_choice': 'Console server not found',
        }
    )
    cs_port = forms.CharField(
        help_text='Console server port name'
    )
    device = FlexibleModelChoiceField(
        queryset=Device.objects.all(),
        to_field_name='name',
        help_text='Device name or ID',
        error_messages={
            'invalid_choice': 'Device not found',
        }
    )
    console_port = forms.CharField(
        help_text='Console port name'
    )
    connection_status = CSVChoiceField(
        choices=CONNECTION_STATUS_CHOICES,
        help_text='Connection status'
    )

    class Meta:
        model = ConsolePort
        fields = ['console_server', 'cs_port', 'device', 'console_port', 'connection_status']

    def clean_console_port(self):

        console_port_name = self.cleaned_data.get('console_port')
        if not self.cleaned_data.get('device') or not console_port_name:
            return None

        try:
            # Retrieve console port by name
            consoleport = ConsolePort.objects.get(
                device=self.cleaned_data['device'], name=console_port_name
            )
            # Check if the console port is already connected
            if consoleport.cs_port is not None:
                raise forms.ValidationError("{} {} is already connected".format(
                    self.cleaned_data['device'], console_port_name
                ))
        except ConsolePort.DoesNotExist:
            raise forms.ValidationError("Invalid console port ({} {})".format(
                self.cleaned_data['device'], console_port_name
            ))

        self.instance = consoleport
        return consoleport

    def clean_cs_port(self):

        cs_port_name = self.cleaned_data.get('cs_port')
        if not self.cleaned_data.get('console_server') or not cs_port_name:
            return None

        try:
            # Retrieve console server port by name
            cs_port = ConsoleServerPort.objects.get(
                device=self.cleaned_data['console_server'], name=cs_port_name
            )
            # Check if the console server port is already connected
            if ConsolePort.objects.filter(cs_port=cs_port).count():
                raise forms.ValidationError("{} {} is already connected".format(
                    self.cleaned_data['console_server'], cs_port_name
                ))
        except ConsoleServerPort.DoesNotExist:
            raise forms.ValidationError("Invalid console server port ({} {})".format(
                self.cleaned_data['console_server'], cs_port_name
            ))

        return cs_port


class ConsolePortConnectionForm(BootstrapMixin, ChainedFieldsMixin, forms.ModelForm):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        required=False,
        widget=forms.Select(
            attrs={'filter-for': 'rack'}
        )
    )
    rack = ChainedModelChoiceField(
        queryset=Rack.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        label='Rack',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/racks/?site_id={{site}}',
            attrs={'filter-for': 'console_server', 'nullable': 'true'}
        )
    )
    console_server = ChainedModelChoiceField(
        queryset=Device.objects.filter(device_type__is_console_server=True),
        chains=(
            ('site', 'site'),
            ('rack', 'rack'),
        ),
        label='Console Server',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/devices/?site_id={{site}}&rack_id={{rack}}&is_console_server=True',
            display_field='display_name',
            attrs={'filter-for': 'cs_port'}
        )
    )
    livesearch = forms.CharField(
        required=False,
        label='Console Server',
        widget=Livesearch(
            query_key='q',
            query_url='dcim-api:device-list',
            field_to_update='console_server',
        )
    )
    cs_port = ChainedModelChoiceField(
        queryset=ConsoleServerPort.objects.all(),
        chains=(
            ('device', 'console_server'),
        ),
        label='Port',
        widget=APISelect(
            api_url='/api/dcim/console-server-ports/?device_id={{console_server}}',
            disabled_indicator='connected_console',
        )
    )

    class Meta:
        model = ConsolePort
        fields = ['site', 'rack', 'console_server', 'livesearch', 'cs_port', 'connection_status']
        labels = {
            'cs_port': 'Port',
            'connection_status': 'Status',
        }

    def __init__(self, *args, **kwargs):

        super(ConsolePortConnectionForm, self).__init__(*args, **kwargs)

        if not self.instance.pk:
            raise RuntimeError("ConsolePortConnectionForm must be initialized with an existing ConsolePort instance.")


#
# Console server ports
#

class ConsoleServerPortForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = ConsoleServerPort
        fields = ['device', 'name']
        widgets = {
            'device': forms.HiddenInput(),
        }


class ConsoleServerPortCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


class ConsoleServerPortConnectionForm(BootstrapMixin, ChainedFieldsMixin, forms.Form):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        required=False,
        widget=forms.Select(
            attrs={'filter-for': 'rack'}
        )
    )
    rack = ChainedModelChoiceField(
        queryset=Rack.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        label='Rack',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/racks/?site_id={{site}}',
            attrs={'filter-for': 'device', 'nullable': 'true'}
        )
    )
    device = ChainedModelChoiceField(
        queryset=Device.objects.all(),
        chains=(
            ('site', 'site'),
            ('rack', 'rack'),
        ),
        label='Device',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/devices/?site_id={{site}}&rack_id={{rack}}',
            display_field='display_name',
            attrs={'filter-for': 'port'}
        )
    )
    livesearch = forms.CharField(
        required=False,
        label='Device',
        widget=Livesearch(
            query_key='q',
            query_url='dcim-api:device-list',
            field_to_update='device'
        )
    )
    port = ChainedModelChoiceField(
        queryset=ConsolePort.objects.all(),
        chains=(
            ('device', 'device'),
        ),
        label='Port',
        widget=APISelect(
            api_url='/api/dcim/console-ports/?device_id={{device}}',
            disabled_indicator='cs_port'
        )
    )
    connection_status = forms.BooleanField(
        required=False,
        initial=CONNECTION_STATUS_CONNECTED,
        label='Status',
        widget=forms.Select(
            choices=CONNECTION_STATUS_CHOICES
        )
    )

    class Meta:
        fields = ['site', 'rack', 'device', 'livesearch', 'port', 'connection_status']
        labels = {
            'connection_status': 'Status',
        }


class ConsoleServerPortBulkRenameForm(BulkRenameForm):
    pk = forms.ModelMultipleChoiceField(queryset=ConsoleServerPort.objects.all(), widget=forms.MultipleHiddenInput)


class ConsoleServerPortBulkDisconnectForm(ConfirmationForm):
    pk = forms.ModelMultipleChoiceField(queryset=ConsoleServerPort.objects.all(), widget=forms.MultipleHiddenInput)


#
# Power ports
#

class PowerPortForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = PowerPort
        fields = ['device', 'name']
        widgets = {
            'device': forms.HiddenInput(),
        }


class PowerPortCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


class PowerConnectionCSVForm(forms.ModelForm):
    pdu = FlexibleModelChoiceField(
        queryset=Device.objects.filter(device_type__is_pdu=True),
        to_field_name='name',
        help_text='PDU name or ID',
        error_messages={
            'invalid_choice': 'PDU not found.',
        }
    )
    power_outlet = forms.CharField(
        help_text='Power outlet name'
    )
    device = FlexibleModelChoiceField(
        queryset=Device.objects.all(),
        to_field_name='name',
        help_text='Device name or ID',
        error_messages={
            'invalid_choice': 'Device not found',
        }
    )
    power_port = forms.CharField(
        help_text='Power port name'
    )
    connection_status = CSVChoiceField(
        choices=CONNECTION_STATUS_CHOICES,
        help_text='Connection status'
    )

    class Meta:
        model = PowerPort
        fields = ['pdu', 'power_outlet', 'device', 'power_port', 'connection_status']

    def clean_power_port(self):

        power_port_name = self.cleaned_data.get('power_port')
        if not self.cleaned_data.get('device') or not power_port_name:
            return None

        try:
            # Retrieve power port by name
            powerport = PowerPort.objects.get(
                device=self.cleaned_data['device'], name=power_port_name
            )
            # Check if the power port is already connected
            if powerport.power_outlet is not None:
                raise forms.ValidationError("{} {} is already connected".format(
                    self.cleaned_data['device'], power_port_name
                ))
        except PowerPort.DoesNotExist:
            raise forms.ValidationError("Invalid power port ({} {})".format(
                self.cleaned_data['device'], power_port_name
            ))

        self.instance = powerport
        return powerport

    def clean_power_outlet(self):

        power_outlet_name = self.cleaned_data.get('power_outlet')
        if not self.cleaned_data.get('pdu') or not power_outlet_name:
            return None

        try:
            # Retrieve power outlet by name
            power_outlet = PowerOutlet.objects.get(
                device=self.cleaned_data['pdu'], name=power_outlet_name
            )
            # Check if the power outlet is already connected
            if PowerPort.objects.filter(power_outlet=power_outlet).count():
                raise forms.ValidationError("{} {} is already connected".format(
                    self.cleaned_data['pdu'], power_outlet_name
                ))
        except PowerOutlet.DoesNotExist:
            raise forms.ValidationError("Invalid power outlet ({} {})".format(
                self.cleaned_data['pdu'], power_outlet_name
            ))

        return power_outlet


class PowerPortConnectionForm(BootstrapMixin, ChainedFieldsMixin, forms.ModelForm):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        required=False,
        widget=forms.Select(
            attrs={'filter-for': 'rack'}
        )
    )
    rack = ChainedModelChoiceField(
        queryset=Rack.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        label='Rack',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/racks/?site_id={{site}}',
            attrs={'filter-for': 'pdu', 'nullable': 'true'}
        )
    )
    pdu = ChainedModelChoiceField(
        queryset=Device.objects.all(),
        chains=(
            ('site', 'site'),
            ('rack', 'rack'),
        ),
        label='PDU',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/devices/?site_id={{site}}&rack_id={{rack}}&is_pdu=True',
            display_field='display_name',
            attrs={'filter-for': 'power_outlet'}
        )
    )
    livesearch = forms.CharField(
        required=False,
        label='PDU',
        widget=Livesearch(
            query_key='q',
            query_url='dcim-api:device-list',
            field_to_update='pdu'
        )
    )
    power_outlet = ChainedModelChoiceField(
        queryset=PowerOutlet.objects.all(),
        chains=(
            ('device', 'pdu'),
        ),
        label='Outlet',
        widget=APISelect(
            api_url='/api/dcim/power-outlets/?device_id={{pdu}}',
            disabled_indicator='connected_port'
        )
    )

    class Meta:
        model = PowerPort
        fields = ['site', 'rack', 'pdu', 'livesearch', 'power_outlet', 'connection_status']
        labels = {
            'power_outlet': 'Outlet',
            'connection_status': 'Status',
        }

    def __init__(self, *args, **kwargs):

        super(PowerPortConnectionForm, self).__init__(*args, **kwargs)

        if not self.instance.pk:
            raise RuntimeError("PowerPortConnectionForm must be initialized with an existing PowerPort instance.")


#
# Power outlets
#

class PowerOutletForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = PowerOutlet
        fields = ['device', 'name']
        widgets = {
            'device': forms.HiddenInput(),
        }


class PowerOutletCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


class PowerOutletConnectionForm(BootstrapMixin, ChainedFieldsMixin, forms.Form):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        required=False,
        widget=forms.Select(
            attrs={'filter-for': 'rack'}
        )
    )
    rack = ChainedModelChoiceField(
        queryset=Rack.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        label='Rack',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/racks/?site_id={{site}}',
            attrs={'filter-for': 'device', 'nullable': 'true'}
        )
    )
    device = ChainedModelChoiceField(
        queryset=Device.objects.all(),
        chains=(
            ('site', 'site'),
            ('rack', 'rack'),
        ),
        label='Device',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/devices/?site_id={{site}}&rack_id={{rack}}',
            display_field='display_name',
            attrs={'filter-for': 'port'}
        )
    )
    livesearch = forms.CharField(
        required=False,
        label='Device',
        widget=Livesearch(
            query_key='q',
            query_url='dcim-api:device-list',
            field_to_update='device'
        )
    )
    port = ChainedModelChoiceField(
        queryset=PowerPort.objects.all(),
        chains=(
            ('device', 'device'),
        ),
        label='Port',
        widget=APISelect(
            api_url='/api/dcim/power-ports/?device_id={{device}}',
            disabled_indicator='power_outlet'
        )
    )
    connection_status = forms.BooleanField(
        required=False,
        initial=CONNECTION_STATUS_CONNECTED,
        label='Status',
        widget=forms.Select(
            choices=CONNECTION_STATUS_CHOICES
        )
    )

    class Meta:
        fields = ['site', 'rack', 'device', 'livesearch', 'port', 'connection_status']
        labels = {
            'connection_status': 'Status',
        }


class PowerOutletBulkRenameForm(BulkRenameForm):
    pk = forms.ModelMultipleChoiceField(queryset=PowerOutlet.objects.all(), widget=forms.MultipleHiddenInput)


class PowerOutletBulkDisconnectForm(ConfirmationForm):
    pk = forms.ModelMultipleChoiceField(queryset=PowerOutlet.objects.all(), widget=forms.MultipleHiddenInput)


#
# Interfaces
#

class InterfaceForm(BootstrapMixin, forms.ModelForm, ChainedFieldsMixin):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        required=False,
        label='VLAN site',
        widget=forms.Select(
            attrs={'filter-for': 'vlan_group', 'nullable': 'true'},
        )
    )
    vlan_group = ChainedModelChoiceField(
        queryset=VLANGroup.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        required=False,
        label='VLAN group',
        widget=APISelect(
            attrs={'filter-for': 'untagged_vlan tagged_vlans', 'nullable': 'true'},
            api_url='/api/ipam/vlan-groups/?site_id={{site}}',
        )
    )
    untagged_vlan = ChainedModelChoiceField(
        queryset=VLAN.objects.all(),
        chains=(
            ('site', 'site'),
            ('group', 'vlan_group'),
        ),
        required=False,
        label='Untagged VLAN',
        widget=APISelect(
            api_url='/api/ipam/vlans/?site_id={{site}}&group_id={{vlan_group}}',
        )
    )
    tagged_vlans = ChainedModelMultipleChoiceField(
        queryset=VLAN.objects.all(),
        chains=(
            ('site', 'site'),
            ('group', 'vlan_group'),
        ),
        required=False,
        label='Tagged VLANs',
        widget=APISelectMultiple(
            api_url='/api/ipam/vlans/?site_id={{site}}&group_id={{vlan_group}}',
        )
    )

    class Meta:
        model = Interface
        fields = [
            'device', 'name', 'form_factor', 'enabled', 'lag', 'mac_address', 'mtu', 'mgmt_only', 'description',
            'mode', 'site', 'vlan_group', 'untagged_vlan', 'tagged_vlans',
        ]
        widgets = {
            'device': forms.HiddenInput(),
        }

    def __init__(self, *args, **kwargs):
        super(InterfaceForm, self).__init__(*args, **kwargs)

        # Limit LAG choices to interfaces belonging to this device (or VC master)
        if self.is_bound:
            device = Device.objects.get(pk=self.data['device'])
            self.fields['lag'].queryset = Interface.objects.order_naturally().filter(
                device__in=[device, device.get_vc_master()], form_factor=IFACE_FF_LAG
            )
        else:
            device = self.instance.device
            self.fields['lag'].queryset = Interface.objects.order_naturally().filter(
                device__in=[self.instance.device, self.instance.device.get_vc_master()], form_factor=IFACE_FF_LAG
            )

        # Limit the queryset for the site to only include the interface's device's site
        if device and device.site:
            self.fields['site'].queryset = Site.objects.filter(pk=device.site.id)
            self.fields['site'].initial = None
        else:
            self.fields['site'].queryset = Site.objects.none()
            self.fields['site'].initial = None

        # Limit the initial vlan choices
        if self.is_bound:
            filter_dict = {
                'group_id': self.data.get('vlan_group') or None,
                'site_id': self.data.get('site') or None,
            }
        elif self.initial.get('untagged_vlan'):
            filter_dict = {
                'group_id': self.instance.untagged_vlan.group,
                'site_id': self.instance.untagged_vlan.site,
            }
        elif self.initial.get('tagged_vlans'):
            filter_dict = {
                'group_id': self.instance.tagged_vlans.first().group,
                'site_id': self.instance.tagged_vlans.first().site,
            }
        else:
            filter_dict = {
                'group_id': None,
                'site_id': None,
            }

        self.fields['untagged_vlan'].queryset = VLAN.objects.filter(**filter_dict)
        self.fields['tagged_vlans'].queryset = VLAN.objects.filter(**filter_dict)

    def clean_tagged_vlans(self):
        """
        Because tagged_vlans is a many-to-many relationship, validation must be done in the form
        """
        if self.cleaned_data['mode'] == IFACE_MODE_ACCESS and self.cleaned_data['tagged_vlans']:
            raise forms.ValidationError(
                "An Access interface cannot have tagged VLANs."
            )

        if self.cleaned_data['mode'] == IFACE_MODE_TAGGED_ALL and self.cleaned_data['tagged_vlans']:
            raise forms.ValidationError(
                "Interface mode Tagged All implies all VLANs are tagged. "
                "Do not select any tagged VLANs."
            )

        return self.cleaned_data['tagged_vlans']


class InterfaceCreateForm(ComponentForm, ChainedFieldsMixin):
    name_pattern = ExpandableNameField(label='Name')
    form_factor = forms.ChoiceField(choices=IFACE_FF_CHOICES)
    enabled = forms.BooleanField(required=False)
    lag = forms.ModelChoiceField(queryset=Interface.objects.all(), required=False, label='Parent LAG')
    mtu = forms.IntegerField(required=False, min_value=1, max_value=32767, label='MTU')
    mac_address = MACAddressFormField(required=False, label='MAC Address')
    mgmt_only = forms.BooleanField(required=False, label='OOB Management')
    description = forms.CharField(max_length=100, required=False)
    mode = forms.ChoiceField(choices=add_blank_choice(IFACE_MODE_CHOICES), required=False)
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        required=False,
        label='VLAN Site',
        widget=forms.Select(
            attrs={'filter-for': 'vlan_group', 'nullable': 'true'},
        )
    )
    vlan_group = ChainedModelChoiceField(
        queryset=VLANGroup.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        required=False,
        label='VLAN group',
        widget=APISelect(
            attrs={'filter-for': 'untagged_vlan tagged_vlans', 'nullable': 'true'},
            api_url='/api/ipam/vlan-groups/?site_id={{site}}',
        )
    )
    untagged_vlan = ChainedModelChoiceField(
        queryset=VLAN.objects.all(),
        chains=(
            ('site', 'site'),
            ('group', 'vlan_group'),
        ),
        required=False,
        label='Untagged VLAN',
        widget=APISelect(
            api_url='/api/ipam/vlans/?site_id={{site}}&group_id={{vlan_group}}',
        )
    )
    tagged_vlans = ChainedModelMultipleChoiceField(
        queryset=VLAN.objects.all(),
        chains=(
            ('site', 'site'),
            ('group', 'vlan_group'),
        ),
        required=False,
        label='Tagged VLANs',
        widget=APISelectMultiple(
            api_url='/api/ipam/vlans/?site_id={{site}}&group_id={{vlan_group}}',
        )
    )

    def __init__(self, *args, **kwargs):

        # Set interfaces enabled by default
        kwargs['initial'] = kwargs.get('initial', {}).copy()
        kwargs['initial'].update({'enabled': True})

        super(InterfaceCreateForm, self).__init__(*args, **kwargs)

        # Limit LAG choices to interfaces belonging to this device (or its VC master)
        if self.parent is not None:
            self.fields['lag'].queryset = Interface.objects.order_naturally().filter(
                device__in=[self.parent, self.parent.get_vc_master()], form_factor=IFACE_FF_LAG
            )
        else:
            self.fields['lag'].queryset = Interface.objects.none()

        # Limit the queryset for the site to only include the interface's device's site
        if self.parent is not None and self.parent.site:
            self.fields['site'].queryset = Site.objects.filter(pk=self.parent.site.id)
            self.fields['site'].initial = None
        else:
            self.fields['site'].queryset = Site.objects.none()
            self.fields['site'].initial = None

        # Limit the initial vlan choices
        if self.is_bound:
            filter_dict = {
                'group_id': self.data.get('vlan_group') or None,
                'site_id': self.data.get('site') or None,
            }
        elif self.initial.get('untagged_vlan'):
            filter_dict = {
                'group_id': self.untagged_vlan.group,
                'site_id': self.untagged_vlan.site,
            }
        elif self.initial.get('tagged_vlans'):
            filter_dict = {
                'group_id': self.tagged_vlans.first().group,
                'site_id': self.tagged_vlans.first().site,
            }
        else:
            filter_dict = {
                'group_id': None,
                'site_id': None,
            }

        self.fields['untagged_vlan'].queryset = VLAN.objects.filter(**filter_dict)
        self.fields['tagged_vlans'].queryset = VLAN.objects.filter(**filter_dict)


class InterfaceBulkEditForm(BootstrapMixin, BulkEditForm, ChainedFieldsMixin):
    pk = forms.ModelMultipleChoiceField(queryset=Interface.objects.all(), widget=forms.MultipleHiddenInput)
    device = forms.ModelChoiceField(queryset=Device.objects.all(), widget=forms.HiddenInput)
    form_factor = forms.ChoiceField(choices=add_blank_choice(IFACE_FF_CHOICES), required=False)
    enabled = forms.NullBooleanField(required=False, widget=BulkEditNullBooleanSelect)
    lag = forms.ModelChoiceField(queryset=Interface.objects.all(), required=False, label='Parent LAG')
    mtu = forms.IntegerField(required=False, min_value=1, max_value=32767, label='MTU')
    mgmt_only = forms.NullBooleanField(required=False, widget=BulkEditNullBooleanSelect, label='Management only')
    description = forms.CharField(max_length=100, required=False)
    mode = forms.ChoiceField(choices=add_blank_choice(IFACE_MODE_CHOICES), required=False)
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        required=False,
        label='VLAN Site',
        widget=forms.Select(
            attrs={'filter-for': 'vlan_group', 'nullable': 'true'},
        )
    )
    vlan_group = ChainedModelChoiceField(
        queryset=VLANGroup.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        required=False,
        label='VLAN group',
        widget=APISelect(
            attrs={'filter-for': 'untagged_vlan tagged_vlans', 'nullable': 'true'},
            api_url='/api/ipam/vlan-groups/?site_id={{site}}',
        )
    )
    untagged_vlan = ChainedModelChoiceField(
        queryset=VLAN.objects.all(),
        chains=(
            ('site', 'site'),
            ('group', 'vlan_group'),
        ),
        required=False,
        label='Untagged VLAN',
        widget=APISelect(
            api_url='/api/ipam/vlans/?site_id={{site}}&group_id={{vlan_group}}',
        )
    )
    tagged_vlans = ChainedModelMultipleChoiceField(
        queryset=VLAN.objects.all(),
        chains=(
            ('site', 'site'),
            ('group', 'vlan_group'),
        ),
        required=False,
        label='Tagged VLANs',
        widget=APISelectMultiple(
            api_url='/api/ipam/vlans/?site_id={{site}}&group_id={{vlan_group}}',
        )
    )

    class Meta:
        nullable_fields = ['lag', 'mtu', 'description', 'untagged_vlan', 'tagged_vlans']

    def __init__(self, *args, **kwargs):
        super(InterfaceBulkEditForm, self).__init__(*args, **kwargs)

        # Limit LAG choices to interfaces which belong to the parent device (or VC master)
        device = None
        if self.initial.get('device'):
            try:
                device = Device.objects.get(pk=self.initial.get('device'))
            except Device.DoesNotExist:
                pass
        else:
            try:
                device = Device.objects.get(pk=self.data.get('device'))
            except Device.DoesNotExist:
                pass
        if device is not None:
            interface_ordering = device.device_type.interface_ordering
            self.fields['lag'].queryset = Interface.objects.order_naturally(method=interface_ordering).filter(
                device__in=[device, device.get_vc_master()], form_factor=IFACE_FF_LAG
            )
        else:
            self.fields['lag'].choices = []

        # Limit the queryset for the site to only include the interface's device's site
        if device and device.site:
            self.fields['site'].queryset = Site.objects.filter(pk=device.site.id)
            self.fields['site'].initial = None
        else:
            self.fields['site'].queryset = Site.objects.none()
            self.fields['site'].initial = None

        if self.is_bound:
            filter_dict = {
                'group_id': self.data.get('vlan_group') or None,
                'site_id': self.data.get('site') or None,
            }
        else:
            filter_dict = {
                'group_id': None,
                'site_id': None,
            }

        self.fields['untagged_vlan'].queryset = VLAN.objects.filter(**filter_dict)
        self.fields['tagged_vlans'].queryset = VLAN.objects.filter(**filter_dict)


class InterfaceBulkRenameForm(BulkRenameForm):
    pk = forms.ModelMultipleChoiceField(queryset=Interface.objects.all(), widget=forms.MultipleHiddenInput)


class InterfaceBulkDisconnectForm(ConfirmationForm):
    pk = forms.ModelMultipleChoiceField(queryset=Interface.objects.all(), widget=forms.MultipleHiddenInput)


#
# Interface connections
#

class InterfaceConnectionForm(BootstrapMixin, ChainedFieldsMixin, forms.ModelForm):
    interface_a = forms.ChoiceField(
        choices=[],
        widget=SelectWithDisabled,
        label='Interface'
    )
    site_b = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        label='Site',
        required=False,
        widget=forms.Select(
            attrs={'filter-for': 'rack_b'}
        )
    )
    rack_b = ChainedModelChoiceField(
        queryset=Rack.objects.all(),
        chains=(
            ('site', 'site_b'),
        ),
        label='Rack',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/racks/?site_id={{site_b}}',
            attrs={'filter-for': 'device_b', 'nullable': 'true'}
        )
    )
    device_b = ChainedModelChoiceField(
        queryset=Device.objects.all(),
        chains=(
            ('site', 'site_b'),
            ('rack', 'rack_b'),
        ),
        label='Device',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/devices/?site_id={{site_b}}&rack_id={{rack_b}}',
            display_field='display_name',
            attrs={'filter-for': 'interface_b'}
        )
    )
    livesearch = forms.CharField(
        required=False,
        label='Device',
        widget=Livesearch(
            query_key='q',
            query_url='dcim-api:device-list',
            field_to_update='device_b'
        )
    )
    interface_b = ChainedModelChoiceField(
        queryset=Interface.objects.connectable().select_related(
            'circuit_termination', 'connected_as_a', 'connected_as_b'
        ),
        chains=(
            ('device', 'device_b'),
        ),
        label='Interface',
        widget=APISelect(
            api_url='/api/dcim/interfaces/?device_id={{device_b}}&type=physical',
            disabled_indicator='is_connected'
        )
    )

    class Meta:
        model = InterfaceConnection
        fields = ['interface_a', 'site_b', 'rack_b', 'device_b', 'interface_b', 'livesearch', 'connection_status']

    def __init__(self, device_a, *args, **kwargs):

        super(InterfaceConnectionForm, self).__init__(*args, **kwargs)

        # Initialize interface A choices
        device_a_interfaces = Interface.objects.connectable().order_naturally().filter(device=device_a).select_related(
            'circuit_termination', 'connected_as_a', 'connected_as_b'
        )
        self.fields['interface_a'].choices = [
            (iface.id, {'label': iface.name, 'disabled': iface.is_connected}) for iface in device_a_interfaces
        ]

        # Mark connected interfaces as disabled
        if self.data.get('device_b'):
            self.fields['interface_b'].choices = [
                (iface.id, {'label': iface.name, 'disabled': iface.is_connected}) for iface in self.fields['interface_b'].queryset
            ]


class InterfaceConnectionCSVForm(forms.ModelForm):
    device_a = FlexibleModelChoiceField(
        queryset=Device.objects.all(),
        to_field_name='name',
        help_text='Name or ID of device A',
        error_messages={'invalid_choice': 'Device A not found.'}
    )
    interface_a = forms.CharField(
        help_text='Name of interface A'
    )
    device_b = FlexibleModelChoiceField(
        queryset=Device.objects.all(),
        to_field_name='name',
        help_text='Name or ID of device B',
        error_messages={'invalid_choice': 'Device B not found.'}
    )
    interface_b = forms.CharField(
        help_text='Name of interface B'
    )
    connection_status = CSVChoiceField(
        choices=CONNECTION_STATUS_CHOICES,
        help_text='Connection status'
    )

    class Meta:
        model = InterfaceConnection
        fields = InterfaceConnection.csv_headers

    def clean_interface_a(self):

        interface_name = self.cleaned_data.get('interface_a')
        if not interface_name:
            return None

        try:
            # Retrieve interface by name
            interface = Interface.objects.get(
                device=self.cleaned_data['device_a'], name=interface_name
            )
            # Check for an existing connection to this interface
            if InterfaceConnection.objects.filter(Q(interface_a=interface) | Q(interface_b=interface)).count():
                raise forms.ValidationError("{} {} is already connected".format(
                    self.cleaned_data['device_a'], interface_name
                ))
        except Interface.DoesNotExist:
            raise forms.ValidationError("Invalid interface ({} {})".format(
                self.cleaned_data['device_a'], interface_name
            ))

        return interface

    def clean_interface_b(self):

        interface_name = self.cleaned_data.get('interface_b')
        if not interface_name:
            return None

        try:
            # Retrieve interface by name
            interface = Interface.objects.get(
                device=self.cleaned_data['device_b'], name=interface_name
            )
            # Check for an existing connection to this interface
            if InterfaceConnection.objects.filter(Q(interface_a=interface) | Q(interface_b=interface)).count():
                raise forms.ValidationError("{} {} is already connected".format(
                    self.cleaned_data['device_b'], interface_name
                ))
        except Interface.DoesNotExist:
            raise forms.ValidationError("Invalid interface ({} {})".format(
                self.cleaned_data['device_b'], interface_name
            ))

        return interface


#
# Device bays
#

class DeviceBayForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = DeviceBay
        fields = ['device', 'name']
        widgets = {
            'device': forms.HiddenInput(),
        }


class DeviceBayCreateForm(ComponentForm):
    name_pattern = ExpandableNameField(label='Name')


class PopulateDeviceBayForm(BootstrapMixin, forms.Form):
    installed_device = forms.ModelChoiceField(
        queryset=Device.objects.all(),
        label='Child Device',
        help_text="Child devices must first be created and assigned to the site/rack of the parent device."
    )

    def __init__(self, device_bay, *args, **kwargs):

        super(PopulateDeviceBayForm, self).__init__(*args, **kwargs)

        self.fields['installed_device'].queryset = Device.objects.filter(
            site=device_bay.device.site,
            rack=device_bay.device.rack,
            parent_bay__isnull=True,
            device_type__u_height=0,
            device_type__subdevice_role=SUBDEVICE_ROLE_CHILD
        ).exclude(pk=device_bay.device.pk)


class DeviceBayBulkRenameForm(BulkRenameForm):
    pk = forms.ModelMultipleChoiceField(queryset=DeviceBay.objects.all(), widget=forms.MultipleHiddenInput)


#
# Connections
#

class ConsoleConnectionFilterForm(BootstrapMixin, forms.Form):
    site = forms.ModelChoiceField(required=False, queryset=Site.objects.all(), to_field_name='slug')
    device = forms.CharField(required=False, label='Device name')


class PowerConnectionFilterForm(BootstrapMixin, forms.Form):
    site = forms.ModelChoiceField(required=False, queryset=Site.objects.all(), to_field_name='slug')
    device = forms.CharField(required=False, label='Device name')


class InterfaceConnectionFilterForm(BootstrapMixin, forms.Form):
    site = forms.ModelChoiceField(required=False, queryset=Site.objects.all(), to_field_name='slug')
    device = forms.CharField(required=False, label='Device name')


#
# Inventory items
#

class InventoryItemForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = InventoryItem
        fields = ['name', 'manufacturer', 'part_id', 'serial', 'asset_tag', 'description']


class InventoryItemCSVForm(forms.ModelForm):
    device = FlexibleModelChoiceField(
        queryset=Device.objects.all(),
        to_field_name='name',
        help_text='Device name or ID',
        error_messages={
            'invalid_choice': 'Device not found.',
        }
    )
    manufacturer = forms.ModelChoiceField(
        queryset=Manufacturer.objects.all(),
        to_field_name='name',
        required=False,
        help_text='Manufacturer name',
        error_messages={
            'invalid_choice': 'Invalid manufacturer.',
        }
    )

    class Meta:
        model = InventoryItem
        fields = InventoryItem.csv_headers


class InventoryItemBulkEditForm(BootstrapMixin, BulkEditForm):
    pk = forms.ModelMultipleChoiceField(queryset=InventoryItem.objects.all(), widget=forms.MultipleHiddenInput)
    manufacturer = forms.ModelChoiceField(queryset=Manufacturer.objects.all(), required=False)
    part_id = forms.CharField(max_length=50, required=False, label='Part ID')
    description = forms.CharField(max_length=100, required=False)

    class Meta:
        nullable_fields = ['manufacturer', 'part_id', 'description']


class InventoryItemFilterForm(BootstrapMixin, forms.Form):
    model = InventoryItem
    q = forms.CharField(required=False, label='Search')
    manufacturer = FilterChoiceField(
        queryset=Manufacturer.objects.annotate(filter_count=Count('inventory_items')),
        to_field_name='slug',
        null_label='-- None --'
    )


#
# Virtual chassis
#

class DeviceSelectionForm(forms.Form):
    pk = forms.ModelMultipleChoiceField(queryset=Device.objects.all(), widget=forms.MultipleHiddenInput)


class VirtualChassisForm(BootstrapMixin, forms.ModelForm):

    class Meta:
        model = VirtualChassis
        fields = ['master', 'domain']


class VCMemberSelectForm(BootstrapMixin, ChainedFieldsMixin, forms.Form):
    site = forms.ModelChoiceField(
        queryset=Site.objects.all(),
        label='Site',
        required=False,
        widget=forms.Select(
            attrs={'filter-for': 'rack'}
        )
    )
    rack = ChainedModelChoiceField(
        queryset=Rack.objects.all(),
        chains=(
            ('site', 'site'),
        ),
        label='Rack',
        required=False,
        widget=APISelect(
            api_url='/api/dcim/racks/?site_id={{site}}',
            attrs={'filter-for': 'device', 'nullable': 'true'}
        )
    )
    device = ChainedModelChoiceField(
        queryset=Device.objects.all(),
        chains=(
            ('site', 'site'),
            ('rack', 'rack'),
        ),
        label='Device',
        widget=APISelect(
            api_url='/api/dcim/devices/?site_id={{site}}&rack_id={{rack}}',
            display_field='display_name'
        )
    )

    def clean_device(self):
        device = self.cleaned_data['device']
        if device.virtual_chassis is not None:
            raise forms.ValidationError("Device {} is already assigned to a virtual chassis.".format(device))


class DeviceVCMembershipForm(forms.ModelForm):

    class Meta:
        model = Device
        fields = ['vc_position', 'vc_priority']
        labels = {
            'vc_position': 'Position',
            'vc_priority': 'Priority',
        }

    def __init__(self, *args, **kwargs):
        super(DeviceVCMembershipForm, self).__init__(*args, **kwargs)

        # Require VC position when assigning a member
        self.fields['vc_position'].required = True

    def clean_vc_position(self):
        vc_position = self.cleaned_data['vc_position']
        if Device.objects.filter(virtual_chassis=self.instance.virtual_chassis, vc_position=vc_position).exists():
            raise forms.ValidationError("A virtual chassis member already exists in this position.")

        return vc_position