65 lines
2.2 KiB
ReStructuredText
65 lines
2.2 KiB
ReStructuredText
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Injecting attributes, items, or call methods of the provided instance
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---------------------------------------------------------------------
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.. currentmodule:: dependency_injector.providers
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In this section you will know how to inject provided instance attribute or item into the other
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provider.
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It also describes how to call a method of the provided instance and use the result of
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this call as an injection value.
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.. literalinclude:: ../../examples/providers/provided_instance.py
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:language: python
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:emphasize-lines: 26-32
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:lines: 3-
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To use the feature you should use the ``.provided`` attribute of the injected provider. This
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attribute helps to specify what happens with the provided instance. You can retrieve an injection
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value from:
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- an attribute of the provided instance
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- an item of the provided instance
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- a call of the provided instance method
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When you use the call of the provided instance method you can specify the injections into this
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method like you do with any other provider.
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You can do nested constructions:
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.. literalinclude:: ../../examples/providers/provided_instance_complex.py
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:language: python
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:emphasize-lines: 24-30
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:lines: 3-
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Attribute ``.provided`` is available for the providers that return instances. Providers that
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have ``.provided`` attribute:
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- :py:class:`Callable` and its subclasses
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- :py:class:`Factory` and its subclasses
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- :py:class:`Singleton` and its subclasses
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- :py:class:`Object`
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- :py:class:`List`
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- :py:class:`Selector`
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- :py:class:`Dependency`
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Special providers like :py:class:`Configuration` or :py:class:`Delegate` do not have the
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``.provided`` attribute.
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Provider subclasses
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-------------------
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When you create a new provider subclass and want to implement the ``.provided`` attribute, you
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should use the :py:class:`ProvidedInstance` provider.
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.. code-block:: python
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@property
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def provided(self):
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"""Return :py:class:`ProvidedInstance` provider."""
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return ProvidedInstance(self)
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In all other cases you should not use :py:class:`ProvidedInstance`, :py:class:`AttributeGetter`,
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:py:class:`ItemGetter`, or :py:class:`MethodCaller` providers directly. Use the ``.provided``
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attribute of the injected provider instead.
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