issue_comments: 655785396

Work in progress: not quite right yet, I need smarter logic for how renamed columns are reflected in the generated INSERT INTO ... SELECT ... query: python def transform_table( self, columns=None, rename=None, change_type=None, pk=None, foreign_keys=None, column_order=None, not_null=None, defaults=None, hash_id=None, extracts=None, ): assert self.exists(), "Cannot transform a table that doesn't exist yet" columns = columns or self.columns_dict if rename is not None or change_type is not None: columns = {rename.get(key, key): change_type.get(key, value) for key, value in columns.items()} new_table_name = "{}_new_{}".format(self.name, os.urandom(6).hex()) previous_columns = set(self.columns_dict.keys()) with self.db.conn: columns = {name: value for (name, value) in columns.items()} new_table = self.db.create_table( new_table_name, columns, pk=pk, foreign_keys=foreign_keys, column_order=column_order, not_null=not_null, defaults=defaults, hash_id=hash_id, extracts=extracts, ) # Copy across data - but only for columns that exist in both new_columns = set(columns.keys()) columns_to_copy = new_columns.intersection(previous_columns) copy_sql = "INSERT INTO [{new_table}] ({new_cols}) SELECT {old_cols} FROM [{old_table}]".format( new_table=new_table_name, old_table=self.name, old_cols=", ".join("[{}]".format(col) for col in columns_to_copy), new_cols=", ".join("[{}]".format(rename.get(col, col)) for col in columns_to_copy), ) self.db.conn.execute(copy_sql) # Drop the old table self.db.conn.execute("DROP TABLE [{}]".format(self.name)) # Rename the new one self.db.conn.execute( "ALTER TABLE [{}] RENAME TO [{}]".format(new_table_name, self.name) ) return self