sqlalchemy.types.Float

class documentation

class Float(Numeric):

Known subclasses: sqlalchemy.dialects.oracle.DOUBLE_PRECISION, sqlalchemy.dialects.postgresql.DOUBLE_PRECISION, sqlalchemy.types.FLOAT, sqlalchemy.types.REAL, sqlalchemy.dialects.firebird.kinterbasdb._FBFloat_kinterbasdb, sqlalchemy.dialects.mssql.pyodbc._MSFloat_pyodbc, sqlalchemy.dialects.mysql.types._FloatType, sqlalchemy.dialects.mysql.types._MatchType, sqlalchemy.dialects.oracle.BINARY_DOUBLE, sqlalchemy.dialects.oracle.BINARY_FLOAT

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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.

Note

The .Float type is designed to receive data from a database type that is explicitly known to be a floating point type (e.g. FLOAT, REAL, others) and not a decimal type (e.g. DECIMAL, NUMERIC, others). If the database column on the server is in fact a Numeric type, such as DECIMAL or NUMERIC, use the .Numeric type or a subclass, otherwise numeric coercion between float/Decimal may or may not function as expected.

Method	`__init__`	Construct a Float.
Method	`result_processor`	Return a conversion function for processing result row values.
Class Variable	`__visit_name__`	Undocumented
Class Variable	`scale`	Undocumented
Instance Variable	`asdecimal`	Undocumented
Instance Variable	`decimal_return_scale`	Undocumented
Instance Variable	`precision`	Undocumented

Inherited from Numeric:

Method	`bind_processor`	Return a conversion function for processing bind values.
Method	`get_dbapi_type`	Return the corresponding type object from the underlying DB-API, if any.
Method	`literal_processor`	Return a conversion function for processing literal values that are to be rendered directly without using binds.
Class Variable	`_default_decimal_return_scale`	Undocumented
Property	`_effective_decimal_return_scale`	Undocumented
Property	`_expression_adaptations`	Undocumented
Property	`python_type`	Return the Python type object expected to be returned by instances of this type, if known.

Inherited from _LookupExpressionAdapter (via Numeric):

Class Comparator Undocumented

Inherited from TypeEngine (via Numeric):

Class	`Comparator`	Base class for custom comparison operations defined at the type level. See `.TypeEngine.comparator_factory`.
Method	`adapt`	Produce an "adapted" form of this type, given an "impl" class to work with.
Method	`as_generic`	Return an instance of the generic type corresponding to this type using heuristic rule. The method may be overridden if this heuristic rule is not sufficient.
Method	`bind_expression`	Given a bind value (i.e. a `.BindParameter` instance), return a SQL expression in its place.
Method	`coerce_compared_value`	Suggest a type for a 'coerced' Python value in an expression.
Method	`column_expression`	Given a SELECT column expression, return a wrapping SQL expression.
Method	`compare_against_backend`	Compare this type against the given backend type.
Method	`compare_values`	Compare two values for equality.
Method	`compile`	Produce a string-compiled form of this `.TypeEngine`.
Method	`dialect_impl`	Return a dialect-specific implementation for this `.TypeEngine`.
Method	`evaluates_none`	Return a copy of this type which has the `.should_evaluate_none` flag set to True.
Method	`with_variant`	Produce a new type object that will utilize the given type when applied to the dialect of the given name.
Class Variable	`hashable`	Flag, if False, means values from this type aren't hashable.
Class Variable	`should_evaluate_none`	If True, the Python constant `None` is considered to be handled explicitly by this type.
Class Variable	`sort_key_function`	A sorting function that can be passed as the key to sorted.
Static Method	`_to_instance`	Undocumented
Method	`__repr__`	Undocumented
Method	`__str__`	Undocumented
Method	`_cached_bind_processor`	Return a dialect-specific bind processor for this type.
Method	`_cached_custom_processor`	Undocumented
Method	`_cached_literal_processor`	Return a dialect-specific literal processor for this type.
Method	`_cached_result_processor`	Return a dialect-specific result processor for this type.
Method	`_compare_type_affinity`	Undocumented
Method	`_default_dialect`	Undocumented
Method	`_dialect_info`	Return a dialect-specific registry which caches a dialect-specific implementation, bind processing function, and one or more result processing functions.
Method	`_gen_dialect_impl`	Undocumented
Method	`_resolve_for_literal`	adjust this type given a literal Python value that will be stored in a bound parameter.
Method	`_unwrapped_dialect_impl`	Return the 'unwrapped' dialect impl for this type.
Method	`copy`	Undocumented
Method	`copy_value`	Undocumented
Class Variable	`_is_array`	Undocumented
Class Variable	`_is_table_value`	Undocumented
Class Variable	`_is_tuple_type`	Undocumented
Class Variable	`_is_type_decorator`	Undocumented
Class Variable	`_isnull`	Undocumented
Class Variable	`_sqla_type`	Undocumented
Property	`_generic_type_affinity`	Undocumented
Property	`_has_bind_expression`	memoized boolean, check if bind_expression is implemented.
Property	`_has_column_expression`	memoized boolean, check if column_expression is implemented.
Property	`_static_cache_key`	Undocumented
Property	`_type_affinity`	Return a rudimental 'affinity' value expressing the general class of type.

Inherited from Traversible (via Numeric, TypeEngine):

Method	`get_children`	Return immediate child `.visitors.Traversible` elements of this `.visitors.Traversible`.
Method	`__class_getitem__`	Undocumented

def __init__(self, precision=None, asdecimal=False, decimal_return_scale=None):

overrides sqlalchemy.types.Numeric.__init__

overridden in sqlalchemy.dialects.mssql.REAL, sqlalchemy.dialects.mysql.types.FLOAT, sqlalchemy.dialects.mysql.types.REAL, sqlalchemy.dialects.mysql.types._FloatType, sqlalchemy.dialects.mysql.types._MatchType

Construct a Float.

Parameters
precision	the numeric precision for use in DDL `CREATE TABLE`.
asdecimal	the same flag as that of `.Numeric`, but defaults to `False`. Note that setting this flag to `True` results in floating point conversion.
decimal_return_scale	Default scale to use when converting from floats to Python decimals. Floating point values will typically be much longer due to decimal inaccuracy, and most floating point database types don't have a notion of "scale", so by default the float type looks for the first ten decimal places when converting. Specifying this value will override that length. Note that the MySQL float types, which do include "scale", will use "scale" as the default for decimal_return_scale, if not otherwise specified. New in version 0.9.0.

def result_processor(self, dialect, coltype):

overrides sqlalchemy.types.Numeric.result_processor

Return a conversion function for processing result row values.

Returns a callable which will receive a result row column value as the sole positional argument and will return a value to return to the user.

If processing is not necessary, the method should return None.

Note

This method is only called relative to a dialect specific type object, which is often private to a dialect in use and is not the same type object as the public facing one, which means it's not feasible to subclass a .types.TypeEngine class in order to provide an alternate _types.TypeEngine.result_processor method, unless subclassing the _types.UserDefinedType class explicitly.

To provide alternate behavior for _types.TypeEngine.result_processor, implement a _types.TypeDecorator class and provide an implementation of _types.TypeDecorator.process_result_value.

Parameters
dialect	Dialect instance in use.
coltype	DBAPI coltype argument received in cursor.description.