elements.py 文件源码

def literal_column(text, type_=None):
    """Produce a :class:`.ColumnClause` object that has the
    :paramref:`.column.is_literal` flag set to True.

    :func:`.literal_column` is similar to :func:`.column`, except that
    it is more often used as a "standalone" column expression that renders
    exactly as stated; while :func:`.column` stores a string name that
    will be assumed to be part of a table and may be quoted as such,
    :func:`.literal_column` can be that, or any other arbitrary column-oriented
    expression.

    :param text: the text of the expression; can be any SQL expression.
      Quoting rules will not be applied. To specify a column-name expression
      which should be subject to quoting rules, use the :func:`column`
      function.

    :param type\_: an optional :class:`~sqlalchemy.types.TypeEngine`
      object which will
      provide result-set translation and additional expression semantics for
      this column. If left as None the type will be NullType.

    .. seealso::

        :func:`.column`

        :func:`.text`

        :ref:`sqlexpression_literal_column`

    """
    return ColumnClause(text, type_=type_, is_literal=True)