netbox/netbox/utilities/api.py

from __future__ import unicode_literals

from django.conf import settings
from django.contrib.contenttypes.models import ContentType

from rest_framework.compat import is_authenticated
from rest_framework.exceptions import APIException
from rest_framework.permissions import BasePermission
from rest_framework.serializers import Field, ModelSerializer, ValidationError


WRITE_OPERATIONS = ['create', 'update', 'partial_update', 'delete']


class ServiceUnavailable(APIException):
    status_code = 503
    default_detail = "Service temporarily unavailable, please try again later."


#
# Authentication
#

class IsAuthenticatedOrLoginNotRequired(BasePermission):
    """
    Returns True if the user is authenticated or LOGIN_REQUIRED is False.
    """
    def has_permission(self, request, view):
        if not settings.LOGIN_REQUIRED:
            return True
        return request.user and is_authenticated(request.user)


#
# Serializers
#

class ValidatedModelSerializer(ModelSerializer):
    """
    Extends the built-in ModelSerializer to enforce calling clean() on the associated model during validation.
    """
    def validate(self, data):

        # Remove custom field data (if any) prior to model validation
        attrs = data.copy()
        attrs.pop('custom_fields', None)

        # Run clean() on an instance of the model
        if self.instance is None:
            instance = self.Meta.model(**attrs)
        else:
            instance = self.instance
            for k, v in attrs.items():
                setattr(instance, k, v)
        instance.clean()

        return data


class ChoiceFieldSerializer(Field):
    """
    Represent a ChoiceField as {'value': <DB value>, 'label': <string>}.
    """
    def __init__(self, choices, **kwargs):
        self._choices = dict()
        for k, v in choices:
            # Unpack grouped choices
            if type(v) in [list, tuple]:
                for k2, v2 in v:
                    self._choices[k2] = v2
            else:
                self._choices[k] = v
        super(ChoiceFieldSerializer, self).__init__(**kwargs)

    def to_representation(self, obj):
        return {'value': obj, 'label': self._choices[obj]}

    def to_internal_value(self, data):
        return self._choices.get(data)


class ContentTypeFieldSerializer(Field):
    """
    Represent a ContentType as '<app_label>.<model>'
    """
    def to_representation(self, obj):
        return "{}.{}".format(obj.app_label, obj.model)

    def to_internal_value(self, data):
        app_label, model = data.split('.')
        try:
            return ContentType.objects.get_by_natural_key(app_label=app_label, model=model)
        except ContentType.DoesNotExist:
            raise ValidationError("Invalid content type")


#
# Mixins
#

class WritableSerializerMixin(object):
    """
    Allow for the use of an alternate, writable serializer class for write operations (e.g. POST, PUT).
    """
    def get_serializer_class(self):
        if self.action in WRITE_OPERATIONS and hasattr(self, 'write_serializer_class'):
            return self.write_serializer_class
        return self.serializer_class