Fixed #18681 -- BaseModelAdmin.get_form and InlineModelAdmin.get_formset no longer bypass get_fieldsets

Thanks msopacua for the report.

django/contrib/admin/options.py

@@ -498,7 +498,7 @@ class ModelAdmin(BaseModelAdmin):
         "Hook for specifying fieldsets for the add form."
         if self.declared_fieldsets:
             return self.declared_fieldsets
-        form = self.get_form(request, obj)
+        form = self.get_form(request, obj, fields=None)
         fields = list(form.base_fields) + list(self.get_readonly_fields(request, obj))
         return [(None, {'fields': fields})]
 
@@ -507,10 +507,10 @@ class ModelAdmin(BaseModelAdmin):
         Returns a Form class for use in the admin add view. This is used by
         add_view and change_view.
         """
-        if self.declared_fieldsets:
+        if 'fields' in kwargs:
-            fields = flatten_fieldsets(self.declared_fieldsets)
+            fields = kwargs.pop('fields')
         else:
-            fields = None
+            fields = flatten_fieldsets(self.get_fieldsets(request, obj))
         if self.exclude is None:
             exclude = []
         else:
@@ -1518,10 +1518,10 @@ class InlineModelAdmin(BaseModelAdmin):
 
     def get_formset(self, request, obj=None, **kwargs):
         """Returns a BaseInlineFormSet class for use in admin add/change views."""
-        if self.declared_fieldsets:
+        if 'fields' in kwargs:
-            fields = flatten_fieldsets(self.declared_fieldsets)
+            fields = kwargs.pop('fields')
         else:
-            fields = None
+            fields = flatten_fieldsets(self.get_fieldsets(request, obj))
         if self.exclude is None:
             exclude = []
         else:
@@ -1593,7 +1593,7 @@ class InlineModelAdmin(BaseModelAdmin):
     def get_fieldsets(self, request, obj=None):
         if self.declared_fieldsets:
             return self.declared_fieldsets
-        form = self.get_formset(request, obj).form
+        form = self.get_formset(request, obj, fields=None).form
         fields = list(form.base_fields) + list(self.get_readonly_fields(request, obj))
         return [(None, {'fields': fields})]
 

tests/modeladmin/tests.py

@@ -64,6 +64,30 @@ class ModelAdminTests(TestCase):
         self.assertEqual(ma.get_fieldsets(request, self.band),
             [(None, {'fields': ['name', 'bio', 'sign_date']})])
 
+    def test_get_fieldsets(self):
+        # Test that get_fieldsets is called when figuring out form fields.
+        # Refs #18681.
+
+        class BandAdmin(ModelAdmin):
+            def get_fieldsets(self, request, obj=None):
+                return [(None, {'fields': ['name', 'bio']})]
+
+        ma = BandAdmin(Band, self.site)
+        form = ma.get_form(None)
+        self.assertEqual(form._meta.fields, ['name', 'bio'])
+
+        class InlineBandAdmin(TabularInline):
+            model = Concert
+            fk_name = 'main_band'
+            can_delete = False
+
+            def get_fieldsets(self, request, obj=None):
+                return [(None, {'fields': ['day', 'transport']})]
+
+        ma = InlineBandAdmin(Band, self.site)
+        form = ma.get_formset(None).form
+        self.assertEqual(form._meta.fields, ['day', 'transport'])
+
     def test_field_arguments(self):
         # If we specify the fields argument, fieldsets_add and fielsets_change should
         # just stick the fields into a formsets structure and return it.