python-dependency-injector/docs/providers/provided_instance.rst
2020-09-02 21:17:25 -04:00

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.. _provided-instance:
Injecting provided object attributes, items, or call its methods
================================================================
.. meta::
:keywords: Python,DI,Dependency injection,IoC,Inversion of Control,Attribute,Method,Call
:description: This page demonstrates how to inject attributes, items or call method of the
provided instance.
.. currentmodule:: dependency_injector.providers
You can inject provided object attribute, item or result of its method call.
.. literalinclude:: ../../examples/providers/provided_instance.py
:language: python
:emphasize-lines: 26-32
:lines: 3-
To use the feature you should use the ``.provided`` attribute of the injected provider. This
attribute helps to specify what happens with the provided instance before the injection. You can
use any combination of the following:
- an attribute of the provided object
- an item of the provided object
- a call of the provided object method
When you use a call of the provided instance method you can specify the injections for this
method like you do with any other provider.
You can do nested constructions:
.. literalinclude:: ../../examples/providers/provided_instance_complex.py
:language: python
:emphasize-lines: 24-30
:lines: 3-
The ``.provided`` attribute is available for the next providers:
- :py:class:`Factory` and its subclasses
- :py:class:`Singleton` and its subclasses
- :py:class:`Callable` and its subclasses
- :py:class:`Object`
- :py:class:`List`
- :py:class:`Selector`
- :py:class:`Dependency`
When you create a new provider subclass and want to implement the ``.provided`` attribute, you
should use the :py:class:`ProvidedInstance` provider. Add the ``.provided`` property
implementation to a new subclass:
.. code-block:: python
@property
def provided(self):
return ProvidedInstance(self)
.. disqus::