Closes #4835: Support passing multiple initial values for multiple choice fields

docs/release-notes/version-2.8.md

@@ -5,6 +5,7 @@
 ### Bug Fixes
 
 * [#4821](https://github.com/netbox-community/netbox/issues/4821) - Restrict group options by selected site when bulk editing VLANs
+* [#4835](https://github.com/netbox-community/netbox/issues/4835) - Support passing multiple initial values for multiple choice fields
 
 ---
 

netbox/utilities/forms.py

@@ -594,21 +594,24 @@ class DynamicModelChoiceMixin:
     filter = django_filters.ModelChoiceFilter
     widget = APISelect
 
-    def _get_initial_value(self, initial_data, field_name):
-        return initial_data.get(field_name)
+    def filter_queryset(self, data):
+        field_name = getattr(self, 'to_field_name') or 'pk'
+        # If multiple values have been provided, use only the last.
+        if type(data) in (list, tuple):
+            data = data[-1]
+        filter = self.filter(
+            field_name=field_name
+        )
+        return filter.filter(self.queryset, data)
 
     def get_bound_field(self, form, field_name):
         bound_field = BoundField(form, self, field_name)
 
-        # Override initial() to allow passing multiple values
-        bound_field.initial = self._get_initial_value(form.initial, field_name)
-
         # Modify the QuerySet of the field before we return it. Limit choices to any data already bound: Options
         # will be populated on-demand via the APISelect widget.
         data = bound_field.value()
         if data:
-            filter = self.filter(field_name=self.to_field_name or 'pk', queryset=self.queryset)
-            self.queryset = filter.filter(self.queryset, data)
+            self.queryset = self.filter_queryset(data)
         else:
             self.queryset = self.queryset.none()
 
@@ -638,11 +641,16 @@ class DynamicModelMultipleChoiceField(DynamicModelChoiceMixin, forms.ModelMultip
     filter = django_filters.ModelMultipleChoiceFilter
     widget = APISelectMultiple
 
-    def _get_initial_value(self, initial_data, field_name):
-        # If a QueryDict has been passed as initial form data, get *all* listed values
-        if hasattr(initial_data, 'getlist'):
-            return initial_data.getlist(field_name)
-        return initial_data.get(field_name)
+    def filter_queryset(self, data):
+        field_name = getattr(self, 'to_field_name') or 'pk'
+        # Normalize data to a list
+        if type(data) not in (list, tuple):
+            data = [data]
+        filter = self.filter(
+            field_name=field_name,
+            lookup_expr='in'
+        )
+        return filter.filter(self.queryset, data)
 
 
 class LaxURLField(forms.URLField):

netbox/utilities/tests/test_utils.py

@@ -1,15 +1,13 @@
+from django.http import QueryDict
 from django.test import TestCase
 
-from utilities.utils import deepmerge, dict_to_filter_params
+from utilities.utils import deepmerge, dict_to_filter_params, normalize_querydict
 
 
 class DictToFilterParamsTest(TestCase):
     """
     Validate the operation of dict_to_filter_params().
     """
-    def setUp(self):
-        return
-
     def test_dict_to_filter_params(self):
 
         input = {
@@ -39,13 +37,21 @@ class DictToFilterParamsTest(TestCase):
         self.assertNotEqual(dict_to_filter_params(input), output)
 
 
+class NormalizeQueryDictTest(TestCase):
+    """
+    Validate normalize_querydict() utility function.
+    """
+    def test_normalize_querydict(self):
+        self.assertDictEqual(
+            normalize_querydict(QueryDict('foo=1&bar=2&bar=3&baz=')),
+            {'foo': '1', 'bar': ['2', '3'], 'baz': ''}
+        )
+
+
 class DeepMergeTest(TestCase):
     """
     Validate the behavior of the deepmerge() utility.
     """
-    def setUp(self):
-        return
-
     def test_deepmerge(self):
 
         dict1 = {

netbox/utilities/utils.py

@@ -150,6 +150,24 @@ def dict_to_filter_params(d, prefix=''):
     return params
 
 
+def normalize_querydict(querydict):
+    """
+    Convert a QueryDict to a normal, mutable dictionary, preserving list values. For example,
+
+        QueryDict('foo=1&bar=2&bar=3&baz=')
+
+    becomes:
+
+        {'foo': '1', 'bar': ['2', '3'], 'baz': ''}
+
+    This function is necessary because QueryDict does not provide any built-in mechanism which preserves multiple
+    values.
+    """
+    return {
+        k: v if len(v) > 1 else v[0] for k, v in querydict.lists()
+    }
+
+
 def deepmerge(original, new):
     """
     Deep merge two dictionaries (new into original) and return a new dict

netbox/utilities/views.py

@@ -27,7 +27,7 @@ from extras.models import CustomField, CustomFieldValue, ExportTemplate
 from extras.querysets import CustomFieldQueryset
 from utilities.exceptions import AbortTransaction
 from utilities.forms import BootstrapMixin, CSVDataField, TableConfigForm
-from utilities.utils import csv_format, prepare_cloned_fields
+from utilities.utils import csv_format, normalize_querydict, prepare_cloned_fields
 from .error_handlers import handle_protectederror
 from .forms import ConfirmationForm, ImportForm
 from .paginator import EnhancedPaginator, get_paginate_count
@@ -250,7 +250,7 @@ class ObjectEditView(GetReturnURLMixin, View):
 
     def get(self, request, *args, **kwargs):
         # Parse initial data manually to avoid setting field values as lists
-        initial_data = {k: request.GET[k] for k in request.GET}
+        initial_data = normalize_querydict(request.GET)
         form = self.model_form(instance=self.obj, initial=initial_data)
 
         return render(request, self.template_name, {