Method render_derived

lib/sqlalchemy/sql/selectable.py:1961–2024

Apply "render derived" to this :class:`_sql.TableValuedAlias`. This has the effect of the individual column names listed out after the alias name in the "AS" sequence, e.g.: .. sourcecode:: pycon+sql >>> print( ... select( ...

(
        self,
        name: Optional[str] = None,
        with_types: bool = False,
    )

        return tva

    def render_derived(
        self,
        name: Optional[str] = None,
        with_types: bool = False,
    ) -> TableValuedAlias:
        """Apply "render derived" to this :class:`_sql.TableValuedAlias`.

        This has the effect of the individual column names listed out
        after the alias name in the "AS" sequence, e.g.:

        .. sourcecode:: pycon+sql

            >>> print(
            ...     select(
            ...         func.unnest(array(["one", "two", "three"]))
            ...         .table_valued("x", with_ordinality="o")
            ...         .render_derived()
            ...     )
            ... )
            {printsql}SELECT anon_1.x, anon_1.o
            FROM unnest(ARRAY[%(param_1)s, %(param_2)s, %(param_3)s]) WITH ORDINALITY AS anon_1(x, o)

        The ``with_types`` keyword will render column types inline within
        the alias expression (this syntax currently applies to the
        PostgreSQL database):

        .. sourcecode:: pycon+sql

            >>> print(
            ...     select(
            ...         func.json_to_recordset('[{"a":1,"b":"foo"},{"a":"2","c":"bar"}]')
            ...         .table_valued(column("a", Integer), column("b", String))
            ...         .render_derived(with_types=True)
            ...     )
            ... )
            {printsql}SELECT anon_1.a, anon_1.b FROM json_to_recordset(:json_to_recordset_1)
            AS anon_1(a INTEGER, b VARCHAR)

        :param name: optional string name that will be applied to the alias
         generated.  If left as None, a unique anonymizing name will be used.

        :param with_types: if True, the derived columns will include the
         datatype specification with each column. This is a special syntax
         currently known to be required by PostgreSQL for some SQL functions.

        """  # noqa: E501

        # note: don't use the @_generative system here, keep a reference
        # to the original object.  otherwise you can have reuse of the
        # python id() of the original which can cause name conflicts if
        # a new anon-name grabs the same identifier as the local anon-name
        # (just saw it happen on CI)

        # construct against original to prevent memory growth
        # for repeated generations
        new_alias: TableValuedAlias = TableValuedAlias._construct(
            self.element,
            name=name,