diff options
Diffstat (limited to 'django/db/backends/sqlite3/schema.py')
| -rw-r--r-- | django/db/backends/sqlite3/schema.py | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/django/db/backends/sqlite3/schema.py b/django/db/backends/sqlite3/schema.py index 8c427bee45..add05843c3 100644 --- a/django/db/backends/sqlite3/schema.py +++ b/django/db/backends/sqlite3/schema.py @@ -61,8 +61,27 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor): else: raise ValueError("Cannot quote parameter value %r of type %s" % (value, type(value))) + def _is_referenced_by_fk_constraint(self, table_name, column_name=None, ignore_self=False): + """ + Return whether or not the provided table name is referenced by another + one. If `column_name` is specified, only references pointing to that + column are considered. If `ignore_self` is True, self-referential + constraints are ignored. + """ + with self.connection.cursor() as cursor: + for other_table in self.connection.introspection.get_table_list(cursor): + if ignore_self and other_table.name == table_name: + continue + constraints = self.connection.introspection._get_foreign_key_constraints(cursor, other_table.name) + for constraint in constraints.values(): + constraint_table, constraint_column = constraint['foreign_key'] + if (constraint_table == table_name and + (column_name is None or constraint_column == column_name)): + return True + return False + def alter_db_table(self, model, old_db_table, new_db_table, disable_constraints=True): - if model._meta.related_objects and disable_constraints: + if disable_constraints and self._is_referenced_by_fk_constraint(old_db_table): if self.connection.in_atomic_block: raise NotSupportedError(( 'Renaming the %r table while in a transaction is not ' @@ -77,8 +96,10 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor): def alter_field(self, model, old_field, new_field, strict=False): old_field_name = old_field.name + table_name = model._meta.db_table + _, old_column_name = old_field.get_attname_column() if (new_field.name != old_field_name and - any(r.field_name == old_field.name for r in model._meta.related_objects)): + self._is_referenced_by_fk_constraint(table_name, old_column_name, ignore_self=True)): if self.connection.in_atomic_block: raise NotSupportedError(( 'Renaming the %r.%r column while in a transaction is not ' @@ -93,9 +114,7 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor): with self.connection.cursor() as cursor: schema_version = cursor.execute('PRAGMA schema_version').fetchone()[0] cursor.execute('PRAGMA writable_schema = 1') - table_name = model._meta.db_table references_template = ' REFERENCES "%s" ("%%s") ' % table_name - old_column_name = old_field.get_attname_column()[1] new_column_name = new_field.get_attname_column()[1] search = references_template % old_column_name replacement = references_template % new_column_name |