_json.py 文件源码

def _get_json_oids(conn_or_curs, name='json'):
    # lazy imports
    from psycopg2.extensions import STATUS_IN_TRANSACTION
    from psycopg2.extras import _solve_conn_curs

    conn, curs = _solve_conn_curs(conn_or_curs)

    # Store the transaction status of the connection to revert it after use
    conn_status = conn.status

    # column typarray not available before PG 8.3
    typarray = conn.server_version >= 80300 and "typarray" or "NULL"

    # get the oid for the hstore
    curs.execute(
        "SELECT t.oid, %s FROM pg_type t WHERE t.typname = %%s;"
            % typarray, (name,))
    r = curs.fetchone()

    # revert the status of the connection as before the command
    if (conn_status != STATUS_IN_TRANSACTION and not conn.autocommit):
        conn.rollback()

    if not r:
        raise conn.ProgrammingError("%s data type not found" % name)

    return r