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50 lines
2.2 KiB
ReStructuredText
50 lines
2.2 KiB
ReStructuredText
.. _create-provider:
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Creating a custom provider
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==========================
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.. meta::
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:keywords: Python,DI,Dependency injection,IoC,Inversion of Control,Custom provider, Create
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:description: This page demonstrates how to create a custom provider.
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.. currentmodule:: dependency_injector.providers
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You can create a custom provider.
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To create a custom provider you need to follow these rules:
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1. New provider class should inherit :py:class:`Provider`.
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2. You need to implement the ``Provider._provide()`` method.
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3. You need to implement the ``Provider.__deepcopy__()`` method. It should return an
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equivalent copy of a provider. All providers must be copied with the ``deepcopy()`` function
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from the ``providers`` module. It's essential to pass ``memo`` into ``deepcopy`` in order to keep
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the preconfigured ``args`` and ``kwargs`` of stored providers. After the a new provider object
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is created, use ``Provider._copy_overriding()`` method to copy all overriding providers. See the
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example below.
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4. If new provider has a ``__init__()`` method, it should call the parent
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``Provider.__init__()``.
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5. If new provider stores any other providers, these providers should be listed in
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``.related`` property. Property ``.related`` also should yield providers from parent
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``.related`` property.
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.. literalinclude:: ../../examples/providers/custom_factory.py
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:language: python
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:lines: 3-
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.. note::
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1. Prefer delegation over inheritance. If you choose between inheriting a ``Factory`` or
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inheriting a ``Provider`` and use ``Factory`` internally - the last is better.
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2. When creating a new provider follow the ``Factory``-like injections style. Consistency matters.
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3. Use the ``__slots__`` attribute to make sure nothing could be attached to your provider. You
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will also save some memory.
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.. note::
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If you don't find needed provider in the ``providers`` module and experience troubles creating
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one by your own - open a
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`Github Issue <https://github.com/ets-labs/python-dependency-injector/issues>`_.
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I'll help you to resolve the issue if that's possible. If the new provider can be useful for
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others I'll include it into the ``providers`` module.
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.. disqus::
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