class documentation

class _ColonCast(elements.Cast):

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Undocumented

Method __init__ Produce a CAST expression.
Class Variable __visit​_name__ Undocumented
Instance Variable clause Undocumented
Instance Variable type Undocumented
Instance Variable typeclause Undocumented

Inherited from Cast:

Class Variable ​_traverse​_internals Undocumented
Property ​_from​_objects Undocumented
Property wrapped​_column​_expression Undocumented

Inherited from WrapsColumnExpression (via Cast):

Method ​_dedupe​_anon​_label​_idx Undocumented
Property ​_anon​_name​_label Undocumented
Property ​_non​_anon​_label Undocumented
Property ​_tq​_label Undocumented

Inherited from ColumnElement (via Cast):

Method cast Produce a type cast, i.e. CAST(<expression> AS <type>).
Method label Produce a column label, i.e. <columnname> AS <name>.
Method operate Operate on an argument.
Method reverse​_operate Reverse operate on an argument.
Method self​_group Apply a 'grouping' to this _expression.ClauseElement.
Method shares​_lineage Return True if the given _expression.ColumnElement has a common ancestor to this _expression.ColumnElement.
Class Variable foreign​_keys Undocumented
Class Variable key The 'key' that in some circumstances refers to this object in a Python namespace.
Class Variable primary​_key Undocumented
Method __getattr__ Undocumented
Method ​_anon​_label Undocumented
Method ​_bind​_param Undocumented
Method ​_compare​_name​_for​_result Return True if the given column element compares to this one when targeting within a result row.
Method ​_dedupe​_anon​_label​_idx label to apply to a column that is anon labeled, but repeated in the SELECT, so that we have to make an "extra anon" label that disambiguates it from the previous appearance.
Method ​_dedupe​_anon​_tq​_label​_idx Undocumented
Method ​_expression​_label a suggested label to use in the case that the column has no name, which should be used if possible as the explicit 'AS <label>' where this expression would normally have an anon label.
Method ​_make​_proxy Create a new _expression.ColumnElement representing this _expression.ColumnElement as it appears in the select list of a descending selectable.
Method ​_negate Undocumented
Method ​_proxy​_key Undocumented
Method ​_tq​_key​_label A label-based version of 'key' that in some circumstances refers to this object in a Python namespace.
Method ​_uncached​_proxy​_set An 'uncached' version of proxy set.
Method comparator Undocumented
Class Variable ​_allow​_label​_resolve A flag that can be flipped to prevent a column from being resolvable by string label name.
Class Variable ​_alt​_names Undocumented
Class Variable ​_is​_implicitly​_boolean Undocumented
Class Variable ​_proxies Undocumented
Class Variable ​_render​_label​_in​_columns​_clause No summary
Class Variable ​_tq​_label The named label that can be used to target this column in a result set in a "table qualified" context.
Property ​_anon​_key​_label Provides a constant 'anonymous key label' for this ColumnElement.
Property ​_anon​_name​_label Provides a constant 'anonymous label' for this ColumnElement.
Property ​_anon​_tq​_key​_label Undocumented
Property ​_anon​_tq​_label Undocumented
Property ​_key​_label legacy; renamed to _tq_key_label
Property ​_label legacy; renamed to _tq_label
Property ​_non​_anon​_label the 'name' that naturally applies this element when rendered in SQL.
Property ​_select​_iterable Undocumented
Property anon​_key​_label Undocumented
Property anon​_label Undocumented
Property base​_columns Undocumented
Property expression Return a column expression.
Property proxy​_set Undocumented

Inherited from ColumnArgumentOrKeyRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from SQLRole (via Cast, ColumnElement, ColumnArgumentOrKeyRole, ColumnArgumentRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from StatementOptionRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from SQLRole (via Cast, ColumnElement, StatementOptionRole, StructuralRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from WhereHavingRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from AllowsLambdaRole (via Cast, ColumnElement, WhereHavingRole, OnClauseRole):

Class Variable allows​_lambda Undocumented

Inherited from SQLRole (via Cast, ColumnElement, WhereHavingRole, OnClauseRole, StructuralRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from BinaryElementRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from SQLRole (via Cast, ColumnElement, BinaryElementRole, ExpressionElementRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from OrderByRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from AllowsLambdaRole (via Cast, ColumnElement, OrderByRole):

Class Variable allows​_lambda Undocumented

Inherited from SQLRole (via Cast, ColumnElement, OrderByRole, ByOfRole, ColumnListRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from ColumnsClauseRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from AllowsLambdaRole (via Cast, ColumnElement, ColumnsClauseRole):

Class Variable allows​_lambda Undocumented

Inherited from UsesInspection (via Cast, ColumnElement, ColumnsClauseRole):

Class Variable ​_post​_inspect Undocumented
Class Variable uses​_inspection Undocumented

Inherited from SQLRole (via Cast, ColumnElement, ColumnsClauseRole, ColumnListRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from LimitOffsetRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from SQLRole (via Cast, ColumnElement, LimitOffsetRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from DMLColumnRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from SQLRole (via Cast, ColumnElement, DMLColumnRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from DDLConstraintColumnRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from SQLRole (via Cast, ColumnElement, DDLConstraintColumnRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from DDLExpressionRole (via Cast, ColumnElement):

Class Variable ​_role​_name Undocumented

Inherited from SQLRole (via Cast, ColumnElement, DDLExpressionRole, StructuralRole):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from ColumnOperators (via Cast, ColumnElement):

Method __add__ Implement the + operator.
Method __contains__ Undocumented
Method __div__ Implement the / operator.
Method __eq__ Implement the == operator.
Method __ge__ Implement the >= operator.
Method __getitem__ Implement the [] operator.
Method __gt__ Implement the > operator.
Method __le__ Implement the <= operator.
Method __lshift__ implement the << operator.
Method __lt__ Implement the < operator.
Method __mod__ Implement the % operator.
Method __mul__ Implement the * operator.
Method __ne__ Implement the != operator.
Method __neg__ Implement the - operator.
Method __radd__ Implement the + operator in reverse.
Method __rdiv__ Implement the / operator in reverse.
Method __rmod__ Implement the % operator in reverse.
Method __rmul__ Implement the * operator in reverse.
Method __rshift__ implement the >> operator.
Method __rsub__ Implement the - operator in reverse.
Method __rtruediv__ Implement the // operator in reverse.
Method __sub__ Implement the - operator.
Method __truediv__ Implement the // operator.
Method all​_ Produce an _expression.all_ clause against the parent object.
Method any​_ Produce an _expression.any_ clause against the parent object.
Method asc Produce a _expression.asc clause against the parent object.
Method between Produce a _expression.between clause against the parent object, given the lower and upper range.
Method collate Produce a _expression.collate clause against the parent object, given the collation string.
Method concat Implement the 'concat' operator.
Method contains Implement the 'contains' operator.
Method desc Produce a _expression.desc clause against the parent object.
Method distinct Produce a _expression.distinct clause against the parent object.
Method endswith Implement the 'endswith' operator.
Method ilike Implement the ilike operator, e.g. case insensitive LIKE.
Method in​_ Implement the in operator.
Method is​_ Implement the IS operator.
Method is​_distinct​_from Implement the IS DISTINCT FROM operator.
Method is​_not Implement the IS NOT operator.
Method is​_not​_distinct​_from Implement the IS NOT DISTINCT FROM operator.
Method like Implement the like operator.
Method match Implements a database-specific 'match' operator.
Method not​_ilike implement the NOT ILIKE operator.
Method not​_in implement the NOT IN operator.
Method not​_like implement the NOT LIKE operator.
Method nulls​_first Produce a _expression.nulls_first clause against the parent object.
Method nulls​_last Produce a _expression.nulls_last clause against the parent object.
Method regexp​_match Implements a database-specific 'regexp match' operator.
Method regexp​_replace Implements a database-specific 'regexp replace' operator.
Method startswith Implement the startswith operator.
Class Variable __slots__ Undocumented
Class Variable timetuple Hack, allows datetime objects to be compared on the LHS.

Inherited from Operators (via Cast, ColumnElement, ColumnOperators):

Method __and__ Implement the & operator.
Method __invert__ Implement the ~ operator.
Method __or__ Implement the | operator.
Method bool​_op Return a custom boolean operator.
Method op Produce a generic operator function.

Inherited from ClauseElement (via Cast, ColumnElement):

Method compare Compare this _expression.ClauseElement to the given _expression.ClauseElement.
Method compile Compile this SQL expression.
Method params Return a copy with _expression.bindparam elements replaced.
Method unique​_params Return a copy with _expression.bindparam elements replaced.
Method __bool__ Undocumented
Method __getstate__ Undocumented
Method __invert__ Undocumented
Method __repr__ Undocumented
Method __str__ Undocumented
Method ​_clone Create a shallow copy of this ClauseElement.
Method ​_cloned​_set Return the set consisting all cloned ancestors of this ClauseElement.
Method ​_compile​_w​_cache Undocumented
Method ​_compiler Return a compiler appropriate for this ClauseElement, given a Dialect.
Method ​_execute​_on​_connection Undocumented
Method ​_negate​_in​_binary a hook to allow the right side of a binary expression to respond to a negation of the binary expression.
Method ​_replace​_params Undocumented
Method ​_set​_propagate​_attrs Undocumented
Method ​_ungroup Return this _expression.ClauseElement without any groupings.
Method ​_with​_binary​_element​_type in the context of binary expression, convert the type of this object to the one given.
Class Variable ​_cache​_key​_traversal Undocumented
Class Variable ​_is​_bind​_parameter Undocumented
Class Variable ​_is​_clause​_list Undocumented
Class Variable ​_is​_clone​_of Undocumented
Class Variable ​_is​_from​_clause Undocumented
Class Variable ​_is​_from​_container Undocumented
Class Variable ​_is​_immutable Undocumented
Class Variable ​_is​_lambda​_element Undocumented
Class Variable ​_is​_returns​_rows Undocumented
Class Variable ​_is​_select​_container Undocumented
Class Variable ​_is​_select​_statement Undocumented
Class Variable ​_is​_singleton​_constant Undocumented
Class Variable ​_is​_text​_clause Undocumented
Class Variable ​_is​_textual Undocumented
Class Variable ​_order​_by​_label​_element Undocumented
Class Variable bind Undocumented
Class Variable description Undocumented
Class Variable is​_clause​_element Undocumented
Class Variable is​_selectable Undocumented
Class Variable stringify​_dialect Undocumented
Class Variable supports​_execution Undocumented
Instance Variable ​_propagate​_attrs like annotations, however these propagate outwards liberally as SQL constructs are built, and are set up at construction time.
Property ​_constructor return the 'constructor' for this ClauseElement.
Property entity​_namespace Undocumented

Inherited from SQLRole (via Cast, ColumnElement, ClauseElement):

Class Variable allows​_lambda Undocumented
Class Variable uses​_inspection Undocumented

Inherited from SupportsWrappingAnnotations (via Cast, ColumnElement, ClauseElement):

Method ​_annotate return a copy of this ClauseElement with annotations updated by the given dictionary.
Method ​_deannotate return a copy of this _expression.ClauseElement with annotations removed.
Method ​_with​_annotations return a copy of this ClauseElement with annotations replaced by the given dictionary.

Inherited from SupportsAnnotations (via Cast, ColumnElement, ClauseElement, SupportsWrappingAnnotations):

Property ​_annotations​_cache​_key Undocumented

Inherited from MemoizedHasCacheKey (via Cast, ColumnElement, ClauseElement):

Method ​_generate​_cache​_key return a cache key.

Inherited from HasCacheKey (via Cast, ColumnElement, ClauseElement, MemoizedHasCacheKey):

Class Variable inherit​_cache Indicate if this .HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.
Class Method ​_generate​_cache​_attrs generate cache key dispatcher for a new class.
Class Method ​_generate​_cache​_key​_for​_object Undocumented
Method ​_gen​_cache​_key return an optional cache key.
Class Variable __slots__ Undocumented
Class Variable ​_hierarchy​_supports​_caching private attribute which may be set to False to prevent the inherit_cache warning from being emitted for a hierarchy of subclasses.
Class Variable ​_is​_has​_cache​_key Undocumented

Inherited from HasCopyInternals (via Cast, ColumnElement, ClauseElement):

Method ​_copy​_internals Reassign internal elements to be clones of themselves.

Inherited from Traversible (via Cast, ColumnElement, ClauseElement):

Method get​_children Return immediate child .visitors.Traversible elements of this .visitors.Traversible.
Method __class​_getitem__ Undocumented
def __init__(self, expression, type_):

Produce a CAST expression.

.cast returns an instance of .Cast.

E.g.:

from sqlalchemy import cast, Numeric

stmt = select(cast(product_table.c.unit_price, Numeric(10, 4)))

The above statement will produce SQL resembling:

SELECT CAST(unit_price AS NUMERIC(10, 4)) FROM product

The .cast function performs two distinct functions when used. The first is that it renders the CAST expression within the resulting SQL string. The second is that it associates the given type (e.g. .TypeEngine class or instance) with the column expression on the Python side, which means the expression will take on the expression operator behavior associated with that type, as well as the bound-value handling and result-row-handling behavior of the type.

Changed in version 0.9.0: .cast now applies the given type to the expression such that it takes effect on the bound-value, e.g. the Python-to-database direction, in addition to the result handling, e.g. database-to-Python, direction.

An alternative to .cast is the .type_coerce function. This function performs the second task of associating an expression with a specific type, but does not render the CAST expression in SQL.

See Also

:ref:`coretutorial_casts`

.type_coerce - an alternative to CAST that coerces the type on the Python side only, which is often sufficient to generate the correct SQL and data coercion.

Parameters
expressionA SQL expression, such as a _expression.ColumnElement expression or a Python string which will be coerced into a bound literal value.
type​_A .TypeEngine class or instance indicating the type to which the CAST should apply.
__visit_name__: str =
clause =

Undocumented

type =

Undocumented

typeclause =