Refs #30591 -- Adjusted table rebuild for non-pk relationship on SQLite.

The existing code was only accounting for primary key changes and not
all unique key fields that can be referenced.

django/db/backends/sqlite3/schema.py

@@ -358,8 +358,8 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
             return self.execute(self._rename_field_sql(model._meta.db_table, old_field, new_field, new_type))
         # Alter by remaking table
         self._remake_table(model, alter_field=(old_field, new_field))
-        # Rebuild tables with FKs pointing to this field if the PK type changed.
-        if old_field.primary_key and new_field.primary_key and old_type != new_type:
+        # Rebuild tables with FKs pointing to this field.
+        if new_field.unique and old_type != new_type:
             related_models = set()
             opts = new_field.model._meta
             for remote_field in opts.related_objects:
@@ -367,9 +367,11 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
                 if remote_field.related_model == model:
                     continue
                 if not remote_field.many_to_many:
+                    if remote_field.field_name == new_field.name:
                         related_models.add(remote_field.related_model)
-                elif remote_field.through._meta.auto_created:
+                elif new_field.primary_key and remote_field.through._meta.auto_created:
                     related_models.add(remote_field.through)
+            if new_field.primary_key:
                 for many_to_many in opts.many_to_many:
                     # Ignore self-relationship since the table was already rebuilt.
                     if many_to_many.related_model == model:

tests/migrations/test_operations.py

@@ -1341,7 +1341,7 @@ class OperationTests(OperationTestBase):
         project_state = self.apply_operations(app_label, ProjectState(), operations=[
             migrations.CreateModel('Rider', fields=[
                 ('id', models.AutoField(primary_key=True)),
-                ('code', models.PositiveIntegerField(unique=True)),
+                ('code', models.IntegerField(unique=True)),
             ]),
             migrations.CreateModel('Pony', fields=[
                 ('id', models.AutoField(primary_key=True)),
@@ -1354,6 +1354,18 @@ class OperationTests(OperationTestBase):
             models.CharField(max_length=100, unique=True),
         )
         self.apply_operations(app_label, project_state, operations=[operation])
+        id_type, id_null = [
+            (c.type_code, c.null_ok)
+            for c in self.get_table_description('%s_rider' % app_label)
+            if c.name == 'code'
+        ][0]
+        fk_type, fk_null = [
+            (c.type_code, c.null_ok)
+            for c in self.get_table_description('%s_pony' % app_label)
+            if c.name == 'rider_id'
+        ][0]
+        self.assertEqual(id_type, fk_type)
+        self.assertEqual(id_null, fk_null)
 
     @skipUnlessDBFeature('supports_foreign_keys')
     def test_alter_field_reloads_state_on_fk_with_to_field_related_name_target_type_change(self):