Fixed #22750, #22248: Model renaming now also alters field FKs

3 files changed, 56 insertions, 16 deletions

diff --git a/django/db/migrations/autodetector.py b/django/db/migrations/autodetector.py
index 469fd1199f..3e3dc242d2 100644
--- a/django/db/migrations/autodetector.py
+++ b/django/db/migrations/autodetector.py
@@ -580,11 +580,21 @@ class MigrationAutodetector(object):
         for app_label, model_name, field_name in sorted(self.old_field_keys.intersection(self.new_field_keys)):
             # Did the field change?
             old_model_name = self.renamed_models.get((app_label, model_name), model_name)
-            old_model_state = self.from_state.models[app_label, old_model_name]
             new_model_state = self.to_state.models[app_label, model_name]
             old_field_name = self.renamed_fields.get((app_label, model_name, field_name), field_name)
-            old_field_dec = self.deep_deconstruct(old_model_state.get_field_by_name(old_field_name))
-            new_field_dec = self.deep_deconstruct(new_model_state.get_field_by_name(field_name))
+            old_field = self.old_apps.get_model(app_label, old_model_name)._meta.get_field_by_name(old_field_name)[0]
+            new_field = self.new_apps.get_model(app_label, model_name)._meta.get_field_by_name(field_name)[0]
+            # Implement any model renames on relations; these are handled by RenameModel
+            # so we need to exclude them from the comparison
+            if hasattr(new_field, "rel") and getattr(new_field.rel, "to", None):
+                rename_key = (
+                    new_field.rel.to._meta.app_label,
+                    new_field.rel.to._meta.object_name.lower(),
+                )
+                if rename_key in self.renamed_models:
+                    new_field.rel.to = old_field.rel.to
+            old_field_dec = self.deep_deconstruct(old_field)
+            new_field_dec = self.deep_deconstruct(new_field)
             if old_field_dec != new_field_dec:
                 self.add_operation(
                     app_label,
diff --git a/django/db/migrations/operations/models.py b/django/db/migrations/operations/models.py
index 06ad280be6..abd7ecd8f1 100644
--- a/django/db/migrations/operations/models.py
+++ b/django/db/migrations/operations/models.py
@@ -113,9 +113,28 @@ class RenameModel(Operation):
         self.new_name = new_name
 
     def state_forwards(self, app_label, state):
+        # Get all of the related objects we need to repoint
+        apps = state.render(skip_cache=True)
+        model = apps.get_model(app_label, self.old_name)
+        related_objects = model._meta.get_all_related_objects()
+        related_m2m_objects = model._meta.get_all_related_many_to_many_objects()
+        # Rename the model
         state.models[app_label, self.new_name.lower()] = state.models[app_label, self.old_name.lower()]
         state.models[app_label, self.new_name.lower()].name = self.new_name
         del state.models[app_label, self.old_name.lower()]
+        # Repoint the FKs and M2Ms pointing to us
+        for related_object in (related_objects + related_m2m_objects):
+            related_key = (
+                related_object.model._meta.app_label,
+                related_object.model._meta.object_name.lower(),
+            )
+            new_fields = []
+            for name, field in state.models[related_key].fields:
+                if name == related_object.field.name:
+                    field = field.clone()
+                    field.rel.to = "%s.%s" % (app_label, self.new_name)
+                new_fields.append((name, field))
+            state.models[related_key].fields = new_fields
 
     def database_forwards(self, app_label, schema_editor, from_state, to_state):
         old_apps = from_state.render()
@@ -123,23 +142,30 @@ class RenameModel(Operation):
         old_model = old_apps.get_model(app_label, self.old_name)
         new_model = new_apps.get_model(app_label, self.new_name)
         if router.allow_migrate(schema_editor.connection.alias, new_model):
+            # Move the main table
             schema_editor.alter_db_table(
                 new_model,
                 old_model._meta.db_table,
                 new_model._meta.db_table,
             )
+            # Alter the fields pointing to us
+            related_objects = old_model._meta.get_all_related_objects()
+            related_m2m_objects = old_model._meta.get_all_related_many_to_many_objects()
+            for related_object in (related_objects + related_m2m_objects):
+                to_field = new_apps.get_model(
+                    related_object.model._meta.app_label,
+                    related_object.model._meta.object_name.lower(),
+                )._meta.get_field_by_name(related_object.field.name)[0]
+                schema_editor.alter_field(
+                    related_object.model,
+                    related_object.field,
+                    to_field,
+                )
 
     def database_backwards(self, app_label, schema_editor, from_state, to_state):
-        old_apps = from_state.render()
-        new_apps = to_state.render()
-        old_model = old_apps.get_model(app_label, self.new_name)
-        new_model = new_apps.get_model(app_label, self.old_name)
-        if router.allow_migrate(schema_editor.connection.alias, new_model):
-            schema_editor.alter_db_table(
-                new_model,
-                old_model._meta.db_table,
-                new_model._meta.db_table,
-            )
+        self.new_name, self.old_name = self.old_name, self.new_name
+        self.database_forwards(app_label, schema_editor, from_state, to_state)
+        self.new_name, self.old_name = self.old_name, self.new_name
 
     def references_model(self, name, app_label=None):
         return (
diff --git a/django/db/migrations/state.py b/django/db/migrations/state.py
index 43454fd99c..40bb279cfc 100644
--- a/django/db/migrations/state.py
+++ b/django/db/migrations/state.py
@@ -38,9 +38,9 @@ class ProjectState(object):
             real_apps=self.real_apps,
         )
 
-    def render(self, include_real=None, ignore_swappable=False):
+    def render(self, include_real=None, ignore_swappable=False, skip_cache=False):
         "Turns the project state into actual models in a new Apps"
-        if self.apps is None:
+        if self.apps is None or skip_cache:
             # Any apps in self.real_apps should have all their models included
             # in the render. We don't use the original model instances as there
             # are some variables that refer to the Apps object.
@@ -87,7 +87,11 @@ class ProjectState(object):
                         ))
                     else:
                         do_pending_lookups(model)
-        return self.apps
+        try:
+            return self.apps
+        finally:
+            if skip_cache:
+                self.apps = None
 
     @classmethod
     def from_apps(cls, apps):