Update get_field_value to handle multiple incoming values

netbox/utilities/forms/utils.py

@@ -1,7 +1,8 @@
 import re
 
 from django import forms
-from django.forms.models import fields_for_model
+from django.forms import MultipleChoiceField
+from django.forms.models import fields_for_model, ModelMultipleChoiceField
 from django.utils.translation import gettext as _
 
 from utilities.choices import unpack_grouped_choices
@@ -139,7 +140,16 @@ def get_field_value(form, field_name):
     if form.is_bound and field_name in form.data:
         if (value := form.data[field_name]) is None:
             return
-        if hasattr(field, 'valid_value') and field.valid_value(value):
+        if isinstance(field, (MultipleChoiceField, ModelMultipleChoiceField)) and isinstance(value, (list, tuple)):
+            values = []
+            for v in value:
+                if hasattr(field, 'valid_value') and field.valid_value(v):
+                    values.append(v)
+
+            if values:
+                return values
+
+        elif hasattr(field, 'valid_value') and field.valid_value(value):
             return value
 
     return form.get_initial_for_field(field, field_name)

netbox/utilities/tests/test_forms.py

@@ -448,3 +448,30 @@ class GetFieldValueTest(TestCase):
             get_field_value(form, 'site'),
             None
         )
+
+
+class MultipleGetFieldValueTest(GetFieldValueTest):
+    @classmethod
+    def setUpTestData(cls):
+        super().setUpTestData()
+
+        class TestForm(forms.Form):
+            site = forms.ModelMultipleChoiceField(
+                queryset=Site.objects.all(),
+                required=False
+            )
+        cls.form_class = TestForm
+
+    def test_bound_with_list_without_initial(self):
+        form = self.form_class({'site': (self.sites[0].pk, self.sites[1].pk)}, initial={'site': None})
+        self.assertEqual(
+            get_field_value(form, 'site'),
+            [self.sites[0].pk, self.sites[1].pk]
+        )
+
+    def test_bound_with_list_with_initial(self):
+        form = self.form_class({'site': (self.sites[0].pk, self.sites[1].pk)}, initial={'site': self.sites[0]})
+        self.assertEqual(
+            get_field_value(form, 'site'),
+            [self.sites[0].pk, self.sites[1].pk]
+        )