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73 lines
2.5 KiB
ReStructuredText
73 lines
2.5 KiB
ReStructuredText
.. _aggregate-provider:
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Aggregate 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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Aggregate,Polymorphism,Environment Variable,Flexibility
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:description: Aggregate provider aggregates other providers.
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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 Aggregate provider.
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:py:class:`Aggregate` provider aggregates a group of other providers.
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.. currentmodule:: dependency_injector.providers
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.. literalinclude:: ../../examples/providers/aggregate.py
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:language: python
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:lines: 3-
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:emphasize-lines: 24-27
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Each provider in the ``Aggregate`` is associated with a key. You can call aggregated providers by providing
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their key as a first argument. All positional and keyword arguments following the key will be forwarded to
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the called provider:
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.. code-block:: python
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yaml_reader = container.config_readers("yaml", "./config.yml", foo=...)
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You can also retrieve an aggregated provider by providing its key as an attribute name:
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.. code-block:: python
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yaml_reader = container.config_readers.yaml("./config.yml", foo=...)
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To retrieve a dictionary of aggregated providers, use ``.providers`` attribute:
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.. code-block:: python
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container.config_readers.providers == {
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"yaml": <YAML provider>,
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"json": <JSON provider>,
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}
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.. note::
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You can not override the ``Aggregate`` provider.
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.. note::
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When you inject the ``Aggregate`` provider, it is passed "as is".
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To use non-string keys or string keys with ``.`` and ``-``, provide a dictionary as a positional argument:
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.. code-block:: python
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aggregate = providers.Aggregate({
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SomeClass: providers.Factory(...),
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"key.with.periods": providers.Factory(...),
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"key-with-dashes": providers.Factory(...),
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})
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.. seealso::
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:ref:`selector-provider` to make injections based on a configuration value, environment variable, or a result of a callable.
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``Aggregate`` provider is different from the :ref:`selector-provider`. ``Aggregate`` provider doesn't select which provider
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to inject and doesn't have a selector. It is a group of providers and is always injected "as is". The rest of the interface
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of both providers is similar.
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.. note::
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``Aggregate`` provider is a successor of :ref:`factory-aggregate-provider` provider. ``Aggregate`` provider doesn't have
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a restriction on the provider type, while ``FactoryAggregate`` aggregates only ``Factory`` providers.
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.. disqus::
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