Refs #26709 -- Added 'model' argument to SchemaEditor.add/remove_index()

This removes the dependency of the Index class on its model attribute
when a name is passed to it.

Thanks to Markush for discussions.

django/db/backends/base/schema.py

@@ -316,17 +316,17 @@ class BaseDatabaseSchemaEditor(object):
             "table": self.quote_name(model._meta.db_table),
         })
 
-    def add_index(self, index):
+    def add_index(self, model, index):
         """
         Add an index on a model.
         """
-        self.execute(index.create_sql(self))
+        self.execute(index.create_sql(model, self))
 
-    def remove_index(self, index):
+    def remove_index(self, model, index):
         """
         Remove an index from a model.
         """
-        self.execute(index.remove_sql(self))
+        self.execute(index.remove_sql(model, self))
 
     def alter_unique_together(self, model, old_unique_together, new_unique_together):
         """

django/db/migrations/operations/models.py

@@ -768,14 +768,15 @@ class AddIndex(IndexOperation):
 
     def state_forwards(self, app_label, state):
         model_state = state.models[app_label, self.model_name_lower]
-        self.index.model = state.apps.get_model(app_label, self.model_name)
         model_state.options[self.option_name].append(self.index)
 
     def database_forwards(self, app_label, schema_editor, from_state, to_state):
-        schema_editor.add_index(self.index)
+        model = to_state.apps.get_model(app_label, self.model_name)
+        schema_editor.add_index(model, self.index)
 
     def database_backwards(self, app_label, schema_editor, from_state, to_state):
-        schema_editor.remove_index(self.index)
+        model = from_state.apps.get_model(app_label, self.model_name)
+        schema_editor.remove_index(model, self.index)
 
     def deconstruct(self):
         kwargs = {
@@ -810,14 +811,16 @@ class RemoveIndex(IndexOperation):
         model_state.options[self.option_name] = [idx for idx in indexes if idx.name != self.name]
 
     def database_forwards(self, app_label, schema_editor, from_state, to_state):
+        model = from_state.apps.get_model(app_label, self.model_name)
         from_model_state = from_state.models[app_label, self.model_name_lower]
         index = from_model_state.get_index_by_name(self.name)
-        schema_editor.remove_index(index)
+        schema_editor.remove_index(model, index)
 
     def database_backwards(self, app_label, schema_editor, from_state, to_state):
+        model = to_state.apps.get_model(app_label, self.model_name)
         to_model_state = to_state.models[app_label, self.model_name_lower]
         index = to_model_state.get_index_by_name(self.name)
-        schema_editor.add_index(index)
+        schema_editor.add_index(model, index)
 
     def deconstruct(self):
         kwargs = {

django/db/models/indexes.py

@@ -45,23 +45,23 @@ class Index(object):
             self._name = 'D%s' % self._name[1:]
         return errors
 
-    def create_sql(self, schema_editor):
-        fields = [self.model._meta.get_field(field) for field in self.fields]
-        tablespace_sql = schema_editor._get_index_tablespace_sql(self.model, fields)
+    def create_sql(self, model, schema_editor):
+        fields = [model._meta.get_field(field) for field in self.fields]
+        tablespace_sql = schema_editor._get_index_tablespace_sql(model, fields)
         columns = [field.column for field in fields]
 
         quote_name = schema_editor.quote_name
         return schema_editor.sql_create_index % {
-            'table': quote_name(self.model._meta.db_table),
+            'table': quote_name(model._meta.db_table),
             'name': quote_name(self.name),
             'columns': ', '.join(quote_name(column) for column in columns),
             'extra': tablespace_sql,
         }
 
-    def remove_sql(self, schema_editor):
+    def remove_sql(self, model, schema_editor):
         quote_name = schema_editor.quote_name
         return schema_editor.sql_delete_index % {
-            'table': quote_name(self.model._meta.db_table),
+            'table': quote_name(model._meta.db_table),
             'name': quote_name(self.name),
         }
 

tests/schema/tests.py

@@ -1455,13 +1455,12 @@ class SchemaTests(TransactionTestCase):
         self.assertNotIn('title', self.get_indexes(Author._meta.db_table))
         # Add the index
         index = Index(fields=['name'], name='author_title_idx')
-        index.model = Author
         with connection.schema_editor() as editor:
-            editor.add_index(index)
+            editor.add_index(Author, index)
         self.assertIn('name', self.get_indexes(Author._meta.db_table))
         # Drop the index
         with connection.schema_editor() as editor:
-            editor.remove_index(index)
+            editor.remove_index(Author, index)
         self.assertNotIn('name', self.get_indexes(Author._meta.db_table))
 
     def test_indexes(self):