34 lines
1.4 KiB
ReStructuredText
34 lines
1.4 KiB
ReStructuredText
.. _selector-provider:
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Selector provider
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=================
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.. meta::
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:keywords: Python,DI,Dependency injection,IoC,Inversion of Control,Configuration,Injection,
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Selector,Polymorphism,Environment Variable,Flexibility
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:description: Selector selects provider based on a configuration value or another callable.
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This page demonstrates how to implement the polymorphism and increase the
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flexibility of your application using the Selector provider.
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.. currentmodule:: dependency_injector.providers
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:py:class:`Selector` provider selects provider based on a configuration value or another callable.
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.. literalinclude:: ../../examples/providers/selector.py
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:language: python
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:lines: 3-
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:emphasize-lines: 14-18
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The first argument of the ``Selector`` provider is called ``selector``. It can be an option of
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a ``Configuration`` provider or any other callable. The ``selector`` callable has to return a
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string value. This value is used as a key for selecting the provider.
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The providers are provided as keyword arguments. Argument name is used as a key for selecting the
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provider.
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When a ``Selector`` provider is called, it gets a ``selector`` value and delegates the work to
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the provider with a matching name. The ``selector`` callable works as a switch: when the returned
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value is changed the ``Selector`` provider will delegate the work to another provider.
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.. disqus::
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