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39 lines
1.4 KiB
ReStructuredText
39 lines
1.4 KiB
ReStructuredText
.. _dependency-provider:
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Dependency provider
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===================
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.. currentmodule:: dependency_injector.providers
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:py:class:`Dependency` provider is a placeholder for a dependency of a certain type.
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To specify a type of the dependency use ``instance_of`` argument: ``Dependency(instance_of=SomeClass)``.
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Dependency provider will control that returned object is an instance of ``instance_of`` type.
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.. literalinclude:: ../../examples/providers/dependency.py
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:language: python
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:lines: 3-
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:emphasize-lines: 26,35-36
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To provide a dependency you need to override the ``Dependency`` provider. You can call
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provider ``.override()`` method or provide an overriding provider when creating a container.
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See :ref:`provider-overriding`. If you don't provide a dependency, ``Dependency`` provider
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will raise an error:
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.. literalinclude:: ../../examples/providers/dependency_undefined_error.py
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:language: python
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:lines: 18-
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You also can provide a default for the dependency. To provide a default use ``default`` argument:
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``Dependency(..., default=...)``. Default can be a value or a provider. If default is not a provider,
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dependency provider will wrap it into the ``Object`` provider.
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.. literalinclude:: ../../examples/providers/dependency_default.py
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:language: python
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:lines: 16-23
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:emphasize-lines: 3
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See also: :ref:`check-container-dependencies`.
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.. disqus::
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