Class Table

piccolo/table.py:239–1525

The class represents a database table. An instance represents a row.

class Table(metaclass=TableMetaclass):
    """
    The class represents a database table. An instance represents a row.
    """

    # These are just placeholder values, so type inference isn't confused - the
    # actual values are set in __init_subclass__.
    _meta = TableMeta()

    def __init_subclass__(
        cls,
        tablename: Optional[str] = None,
        db: Optional[Engine] = None,
        tags: Optional[list[str]] = None,
        help_text: Optional[str] = None,
        schema: Optional[str] = None,
    ):  # sourcery no-metrics
        """
        Automatically populate the _meta, which includes the tablename, and
        columns.

        :param tablename:
            Specify a custom tablename. By default the classname is converted
            to snakecase.
        :param db:
            Manually specify an engine to use for connecting to the database.
            Useful when writing simple scripts. If not set, the engine is
            imported from piccolo_conf.py using ``engine_finder``.
        :param tags:
            Used for filtering, for example by ``table_finder``.
        :param help_text:
            A user friendly description of what the table is used for. It isn't
            used in the database, but will be used by tools such a Piccolo
            Admin for tooltips.
        :param schema:
            The Postgres schema to use for this table.

        """
        if tags is None:
            tags = []
        tablename = tablename or _camel_to_snake(cls.__name__)

        if "." in tablename:
            warnings.warn(
                "There's a '.' in the tablename - please use the `schema` "
                "argument instead."
            )
            schema, tablename = tablename.split(".", maxsplit=1)

        if tablename in PROTECTED_TABLENAMES:
            warnings.warn(TABLENAME_WARNING.format(tablename=tablename))

        columns: list[Column] = []
        default_columns: list[Column] = []
        non_default_columns: list[Column] = []
        array_columns: list[Array] = []
        foreign_key_columns: list[ForeignKey] = []
        secret_columns: list[Column] = []