替代类检测

Alternate Class Instrumentation

中文

可扩展的类注入机制（Instrumentation）

sqlalchemy.ext.instrumentation 模块提供了一种替代方式， 用于在 ORM 中对类进行注入（Instrumentation）处理。 所谓类注入，指的是 ORM 在类上放置用于维护数据和追踪数据变更的属性， 以及安装在类上的事件钩子等机制。

备注

该扩展模块主要用于与其他对象管理系统的集成， 这些系统通常已经实现了自己的注入逻辑。 它 不适用于一般性用途。

有关该注入扩展的使用示例，请参阅：属性检测。

英文

Extensible class instrumentation.

The sqlalchemy.ext.instrumentation package provides for alternate systems of class instrumentation within the ORM. Class instrumentation refers to how the ORM places attributes on the class which maintain data and track changes to that data, as well as event hooks installed on the class.

备注

The extension package is provided for the benefit of integration with other object management packages, which already perform their own instrumentation. It is not intended for general use.

For examples of how the instrumentation extension is used, see the example 属性检测.

API 参考

API Reference

Object Name	Description
ExtendedInstrumentationRegistry	Extends InstrumentationFactory with additional bookkeeping, to accommodate multiple types of class managers.
instrumentation_finders	An extensible sequence of callables which return instrumentation implementations
INSTRUMENTATION_MANAGER	Attribute, elects custom instrumentation when present on a mapped class.
InstrumentationFactory	Factory for new ClassManager instances.
InstrumentationManager	User-defined class instrumentation extension.

sqlalchemy.ext.instrumentation.INSTRUMENTATION_MANAGER = '__sa_instrumentation_manager__'

Attribute, elects custom instrumentation when present on a mapped class.

Allows a class to specify a slightly or wildly different technique for tracking changes made to mapped attributes and collections.

Only one instrumentation implementation is allowed in a given object inheritance hierarchy.

The value of this attribute must be a callable and will be passed a class object. The callable must return one of:

• An instance of an InstrumentationManager or subclass

• An object implementing all or some of InstrumentationManager (TODO)

• A dictionary of callables, implementing all or some of the above (TODO)

• An instance of a ClassManager or subclass

This attribute is consulted by SQLAlchemy instrumentation resolution, once the sqlalchemy.ext.instrumentation module has been imported. If custom finders are installed in the global instrumentation_finders list, they may or may not choose to honor this attribute.

class sqlalchemy.orm.instrumentation.InstrumentationFactory

Factory for new ClassManager instances.

Class signature

class sqlalchemy.orm.instrumentation.InstrumentationFactory (sqlalchemy.event.registry.EventTarget)

class sqlalchemy.ext.instrumentation.InstrumentationManager

User-defined class instrumentation extension.

InstrumentationManager can be subclassed in order to change how class instrumentation proceeds. This class exists for the purposes of integration with other object management frameworks which would like to entirely modify the instrumentation methodology of the ORM, and is not intended for regular usage. For interception of class instrumentation events, see InstrumentationEvents.

Members

dict_getter(), get_instance_dict(), initialize_instance_dict(), install_descriptor(), install_member(), install_state(), instrument_attribute(), instrument_collection_class(), manage(), manager_getter(), post_configure_attribute(), remove_state(), state_getter(), uninstall_descriptor(), uninstall_member(), unregister()

The API for this class should be considered as semi-stable, and may change slightly with new releases.

method sqlalchemy.ext.instrumentation.InstrumentationManager.dict_getter(class_)

method sqlalchemy.ext.instrumentation.InstrumentationManager.get_instance_dict(class_, instance)

method sqlalchemy.ext.instrumentation.InstrumentationManager.initialize_instance_dict(class_, instance)

method sqlalchemy.ext.instrumentation.InstrumentationManager.install_descriptor(class_, key, inst)

method sqlalchemy.ext.instrumentation.InstrumentationManager.install_member(class_, key, implementation)

method sqlalchemy.ext.instrumentation.InstrumentationManager.install_state(class_, instance, state)

method sqlalchemy.ext.instrumentation.InstrumentationManager.instrument_attribute(class_, key, inst)

method sqlalchemy.ext.instrumentation.InstrumentationManager.instrument_collection_class(class_, key, collection_class)

method sqlalchemy.ext.instrumentation.InstrumentationManager.manage(class_, manager)

method sqlalchemy.ext.instrumentation.InstrumentationManager.manager_getter(class_)

method sqlalchemy.ext.instrumentation.InstrumentationManager.post_configure_attribute(class_, key, inst)

method sqlalchemy.ext.instrumentation.InstrumentationManager.remove_state(class_, instance)

method sqlalchemy.ext.instrumentation.InstrumentationManager.state_getter(class_)

method sqlalchemy.ext.instrumentation.InstrumentationManager.uninstall_descriptor(class_, key)

method sqlalchemy.ext.instrumentation.InstrumentationManager.uninstall_member(class_, key)

method sqlalchemy.ext.instrumentation.InstrumentationManager.unregister(class_, manager)

sqlalchemy.ext.instrumentation.instrumentation_finders = [<function find_native_user_instrumentation_hook>]

An extensible sequence of callables which return instrumentation implementations

When a class is registered, each callable will be passed a class object. If None is returned, the next finder in the sequence is consulted. Otherwise the return must be an instrumentation factory that follows the same guidelines as sqlalchemy.ext.instrumentation.INSTRUMENTATION_MANAGER.

By default, the only finder is find_native_user_instrumentation_hook, which searches for INSTRUMENTATION_MANAGER. If all finders return None, standard ClassManager instrumentation is used.

class sqlalchemy.ext.instrumentation.ExtendedInstrumentationRegistry

Extends InstrumentationFactory with additional bookkeeping, to accommodate multiple types of class managers.

Class signature

class sqlalchemy.ext.instrumentation.ExtendedInstrumentationRegistry (sqlalchemy.orm.instrumentation.InstrumentationFactory)