Fix tags field to be shown as array in API view

`tags` field in serializers is defineded as `TagListSerializerField`.
It should be shown as an array value in API view but actually, it is a
simple string value.

This fixes it by introducing a new `FieldInspector` to handle
`TagListSerializerField` type field as an array. It doesn't affects any
other type fields.

netbox/netbox/settings.py

@@ -278,6 +278,7 @@ SWAGGER_SETTINGS = {
     'DEFAULT_FIELD_INSPECTORS': [
         'utilities.custom_inspectors.NullableBooleanFieldInspector',
         'utilities.custom_inspectors.CustomChoiceFieldInspector',
+        'utilities.custom_inspectors.TagListFieldInspector',
         'drf_yasg.inspectors.CamelCaseJSONFilter',
         'drf_yasg.inspectors.ReferencingSerializerInspector',
         'drf_yasg.inspectors.RelatedFieldInspector',

netbox/utilities/custom_inspectors.py

@@ -1,11 +1,25 @@
 from drf_yasg import openapi
 from drf_yasg.inspectors import FieldInspector, NotHandled, PaginatorInspector, FilterInspector
 from rest_framework.fields import ChoiceField
+from taggit_serializer.serializers import TagListSerializerField
 
 from extras.api.customfields import CustomFieldsSerializer
 from utilities.api import ChoiceField
 
 
+class TagListFieldInspector(FieldInspector):
+    def field_to_swagger_object(self, field, swagger_object_type, use_references, **kwargs):
+        SwaggerType, ChildSwaggerType = self._get_partial_types(field, swagger_object_type, use_references, **kwargs)
+        if isinstance(field, TagListSerializerField):
+            child_schema = self.probe_field_inspectors(field.child, ChildSwaggerType, use_references)
+            return SwaggerType(
+                type=openapi.TYPE_ARRAY,
+                items=child_schema,
+            )
+
+        return NotHandled
+
+
 class CustomChoiceFieldInspector(FieldInspector):
     def field_to_swagger_object(self, field, swagger_object_type, use_references, **kwargs):
         # this returns a callable which extracts title, description and other stuff