Class Float

lib/sqlalchemy/sql/sqltypes.py:672–776

Type representing floating point types, such as ``FLOAT`` or ``REAL``. This type returns Python ``float`` objects by default, unless the :paramref:`.Float.asdecimal` flag is set to ``True``, in which case they are coerced to ``decimal.Decimal`` objects. When a :paramref:`.Float.pre

class Float(NumericCommon[_N], TypeEngine[_N]):
    """Type representing floating point types, such as ``FLOAT`` or ``REAL``.

    This type returns Python ``float`` objects by default, unless the
    :paramref:`.Float.asdecimal` flag is set to ``True``, in which case they
    are coerced to ``decimal.Decimal`` objects.

    When a :paramref:`.Float.precision` is not provided in a
    :class:`_types.Float` type some backend may compile this type as
    an 8 bytes / 64 bit float datatype. To use a 4 bytes / 32 bit float
    datatype a precision <= 24 can usually be provided or the
    :class:`_types.REAL` type can be used.
    This is known to be the case in the PostgreSQL and MSSQL dialects
    that render the type as ``FLOAT`` that&#x27;s in both an alias of
    ``DOUBLE PRECISION``. Other third party dialects may have similar
    behavior.
    """

    __visit_name__ = "float"

    @overload
    def __init__(
        self: Float[float],
        precision: Optional[int] = ...,
        asdecimal: Literal[False] = ...,
        decimal_return_scale: Optional[int] = ...,
    ): ...

    @overload
    def __init__(
        self: Float[decimal.Decimal],
        precision: Optional[int] = ...,
        asdecimal: Literal[True] = ...,
        decimal_return_scale: Optional[int] = ...,
    ): ...

    def __init__(
        self: Float[_N],
        precision: Optional[int] = None,
        asdecimal: bool = False,
        decimal_return_scale: Optional[int] = None,
    ):
        r"""
        Construct a Float.

        :param precision: the numeric precision for use in DDL ``CREATE
           TABLE``. Backends **should** attempt to ensure this precision
           indicates a number of digits for the generic
           :class:`_sqltypes.Float` datatype.

           .. note:: For the Oracle Database backend, the
              :paramref:`_sqltypes.Float.precision` parameter is not accepted
              when rendering DDL, as Oracle Database does not support float precision
              specified as a number of decimal places. Instead, use the
              Oracle Database-specific :class:`_oracle.FLOAT` datatype and specify the
              :paramref:`_oracle.FLOAT.binary_precision` parameter. This is new
              in version 2.0 of SQLAlchemy.