Refs #26521 -- Added the duplicated value to CreateModel validation messages.

Thanks Tim for the suggestion.

django/db/migrations/operations/models.py

@@ -17,7 +17,7 @@ def _check_for_duplicates(arg_name, objs):
     for val in objs:
         if val in used_vals:
             raise ValueError(
-                'Found duplicate %s in CreateModel operation.' % arg_name
+                "Found duplicate value %s in CreateModel %s argument." % (val, arg_name)
             )
         used_vals.add(val)
 
@@ -55,14 +55,14 @@ class CreateModel(ModelOperation):
         super(CreateModel, self).__init__(name)
         # Sanity-check that there are no duplicated field names, bases, or
         # manager names
-        _check_for_duplicates("field", (name for name, _ in self.fields))
+        _check_for_duplicates('fields', (name for name, _ in self.fields))
         _check_for_duplicates(
-            "base",
+            'bases',
             (base._meta.label_lower if isinstance(base, models.base.ModelBase) else base.lower()
              for base in self.bases
              if base is not models.Model)
         )
-        _check_for_duplicates("manager", (name for name, _ in self.managers))
+        _check_for_duplicates('managers', (name for name, _ in self.managers))
 
     def deconstruct(self):
         kwargs = {

tests/migrations/test_operations.py

@@ -201,7 +201,7 @@ class OperationTests(OperationTestBase):
         self.assertNotIn('managers', definition[2])
 
     def test_create_model_with_duplicate_field_name(self):
-        with self.assertRaisesMessage(ValueError, "Found duplicate field in CreateModel operation."):
+        with self.assertRaisesMessage(ValueError, 'Found duplicate value pink in CreateModel fields argument.'):
             migrations.CreateModel(
                 "Pony",
                 [
@@ -212,31 +212,33 @@ class OperationTests(OperationTestBase):
             )
 
     def test_create_model_with_duplicate_base(self):
-        with self.assertRaisesMessage(ValueError, "Found duplicate base in CreateModel operation."):
+        message = 'Found duplicate value test_crmo.pony in CreateModel bases argument.'
+        with self.assertRaisesMessage(ValueError, message):
             migrations.CreateModel(
                 "Pony",
                 fields=[],
                 bases=("test_crmo.Pony", "test_crmo.Pony",),
             )
-        with self.assertRaisesMessage(ValueError, "Found duplicate base in CreateModel operation."):
+        with self.assertRaisesMessage(ValueError, message):
-            migrations.CreateModel(
-                "Pony",
-                fields=[],
-                bases=(UnicodeModel, UnicodeModel,),
-            )
-        with self.assertRaisesMessage(ValueError, "Found duplicate base in CreateModel operation."):
             migrations.CreateModel(
                 "Pony",
                 fields=[],
                 bases=("test_crmo.Pony", "test_crmo.pony",),
             )
-        with self.assertRaisesMessage(ValueError, "Found duplicate base in CreateModel operation."):
+        message = 'Found duplicate value migrations.unicodemodel in CreateModel bases argument.'
+        with self.assertRaisesMessage(ValueError, message):
+            migrations.CreateModel(
+                "Pony",
+                fields=[],
+                bases=(UnicodeModel, UnicodeModel,),
+            )
+        with self.assertRaisesMessage(ValueError, message):
             migrations.CreateModel(
                 "Pony",
                 fields=[],
                 bases=(UnicodeModel, 'migrations.unicodemodel',),
             )
-        with self.assertRaisesMessage(ValueError, "Found duplicate base in CreateModel operation."):
+        with self.assertRaisesMessage(ValueError, message):
             migrations.CreateModel(
                 "Pony",
                 fields=[],
@@ -244,7 +246,7 @@ class OperationTests(OperationTestBase):
             )
 
     def test_create_model_with_duplicate_manager_name(self):
-        with self.assertRaisesMessage(ValueError, "Found duplicate manager in CreateModel operation."):
+        with self.assertRaisesMessage(ValueError, 'Found duplicate value objects in CreateModel managers argument.'):
             migrations.CreateModel(
                 "Pony",
                 fields=[],