Section Redefining and Creating New Operators for a description. Which take place for column expressions are most directly redefined at the Operations can be associated with column expressions as well. Itself called operator.eq - the actual SQL construct which SQLAlchemyĪssociates with such an operator can be modified. User.name = 'ed' makes usage of an operator built into Python The “operators” used by the SQLAlchemy ORM and Core expression languageĪre fully customizable. Updated approach to augmenting attribute behavior more flexibly Using Descriptors and Hybrids - The Hybrid Attribute extension provides an Synonym_for() - a helper oriented towards Declarative Is to be replaced with an attribute that also uses aĭescriptor, that is, in conjunction with the This is usually intended to be used when a To the alternate name given as the “name”Īrgument of the synonym in this way, the usual step of redefining This synonym, and produce a new ColumnProperty that instead Table that would normally be associated with the attribute name of ThisĬan refer to the string name ORM-mapped attributeĬonfigured on the class, including column-bound attributesĭescriptor ¶ – a Python descriptor that will be usedĪs a getter (and potentially a setter) when this attribute isįor classical mappings and mappings againstĪn existing Table object only. Name ¶ – the name of the existing mapped property. synonym ( name : str, *, map_column : bool | None = None, descriptor : Any | None = None, comparator_factory : Type ] | None = None, init : _NoArg | bool = _NoArg.NO_ARG, repr : _NoArg | bool = _NoArg.NO_ARG, default : _NoArg | _T = _NoArg.NO_ARG, default_factory : _NoArg | Callable, _T ] = _NoArg.NO_ARG, compare : _NoArg | bool = _NoArg.NO_ARG, kw_only : _NoArg | bool = _NoArg.NO_ARG, info : _InfoType | None = None, doc : str | None = None ) → Synonym ¶ In that the attribute will mirror the value and expression behaviorįunction sqlalchemy.orm. Synonym(name, *, )ĭenote an attribute name as a synonym to a mapped property, Injection of custom SQL capabilities, but the hybrid is more straightforward Technically, a synonym()Ĭan do everything that a hybrid_property can do, as it also supports Is more oriented towards Python descriptors. Usage using the hybrid attribute feature, which Of augmenting attribute behavior with descriptors is better handled in modern While the synonym() is useful for simple mirroring, the use case Validates() usage where only one validator should emit per Validation function will not emit if the originator is an attributeĮvent related via a backref. Sent as well - the validation function must accept an additionalĪrgument “is_remove” which will be a boolean. Include_removes ¶ – if True, “remove” events will be *names ¶ – list of attribute names to be validated. This is a reentrantĬondition which is not supported. Note that a validator for a collection cannot issue a load of thatĬollection within the validation routine - this usage raisesĪn assertion to avoid recursion overflows. Modify or replace the value before proceeding. Process from continuing (where Python’s built-in ValueErrorĪnd AssertionError exceptions are reasonable choices), or can The function can then raise validation exceptions to halt the Name of the attribute as well as a value to be assigned, or in theĬase of a collection, the value to be added to the collection. validates ( * names : str, include_removes : bool = False, include_backrefs : bool = True ) → Callable, _Fn ] ¶ĭesignates a method as a validator, a method which receives the Validates(*names, )ĭecorate a method as a ‘validator’ for one or more named properties.įunction sqlalchemy.orm.

An application that requires more control overĬonfiguration of attribute change behavior can make use of this system,ĭescribed at AttributeEvents. Note that the validates() decorator is a convenience function built on

Occurs to some_user.addresses - the event is caused by a backref. The validate_address() function would not be emitted, even though an append Above, if we were to assign to er as in some_er = some_user,

Decode synonym