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Create multiple containers page
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docs/examples/application-multiple-containers.rst
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87
docs/examples/application-multiple-containers.rst
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.. _application-multiple-containers:
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Application example (multiple containers)
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=========================================
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.. meta::
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:keywords: Python,Dependency Injection,Inversion of Control,Container,Example,Application,
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Framework,AWS,boto3,client
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:description: This example shows how you can create an application using multiple declarative
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containers. We build an example Python micro application following the dependency
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injection principle. It consists from several services with a domain logic that
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have dependencies on database & AWS S3.
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This example shows how you can create an application using multiple declarative containers. Using
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multiple declarative containers is a good choice for a large application. For
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building a moderate or a small size application refer to :ref:`application-single-container`.
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We build an example micro application following the dependency injection principle. It consists
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of several services with a domain logic. The services have dependencies on database & AWS S3.
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.. image:: images/application.png
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:width: 100%
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:align: center
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Start from the scratch or jump to the section:
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.. contents::
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:local:
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:backlinks: none
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You can find the source code and instructions for running on the `Github <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/application-multiple-containers>`_.
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Application structure
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---------------------
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Application consists of an ``example`` package, a configuration file and a ``requirements.txt``
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file.
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.. code-block:: bash
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./
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├── example/
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│ ├── __init__.py
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│ ├── __main__.py
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│ ├── containers.py
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│ └── services.py
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├── config.yml
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└── requirements.txt
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Containers
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----------
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Listing of the ``example/containers.py``:
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.. literalinclude:: ../../examples/miniapps/application-multiple-containers/example/containers.py
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:language: python
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Main module
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-----------
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Listing of the ``example/__main__.py``:
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.. literalinclude:: ../../examples/miniapps/application-multiple-containers/example/__main__.py
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:language: python
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Services
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--------
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Listing of the ``example/services.py``:
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.. literalinclude:: ../../examples/miniapps/application-multiple-containers/example/services.py
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:language: python
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Configuration
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-------------
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Listing of the ``config.yml``:
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.. literalinclude:: ../../examples/miniapps/application-multiple-containers/config.yml
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:language: yaml
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Run the application
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-------------------
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You can find the source code and instructions for running on the `Github <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/application-multiple-containers>`_.
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.. disqus::
|
93
docs/examples/application-single-container.rst
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93
docs/examples/application-single-container.rst
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@ -0,0 +1,93 @@
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.. _application-single-container:
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Application example (single container)
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======================================
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.. meta::
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:keywords: Python,Dependency Injection,Inversion of Control,Container,Example,Application,
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Framework,AWS,boto3,client
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:description: This example shows how you can create an application using a single declarative
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container. We build an example Python micro application following the dependency
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injection principle. It consists from several services with a domain logic that
|
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have dependencies on database & AWS S3.
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This example shows how you can create an application using a single declarative container. Using
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a single declarative container is a good choice for small or moderate size application. For
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building a large application refer to :ref:`application-multiple-containers`.
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We build an example micro application following the dependency injection principle. It consists
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of several services with a domain logic. The services have dependencies on database & AWS S3.
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.. image:: images/application.png
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:width: 100%
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:align: center
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Start from the scratch or jump to the section:
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.. contents::
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:local:
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:backlinks: none
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You can find the source code and instructions for running on the `Github <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/application-single-container>`_.
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Application structure
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---------------------
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Application consists of an ``example`` package, several configuration files and a
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``requirements.txt`` file.
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.. code-block:: bash
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./
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├── example/
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│ ├── __init__.py
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│ ├── __main__.py
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│ ├── containers.py
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│ └── services.py
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├── config.ini
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├── logging.ini
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└── requirements.txt
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Container
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---------
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Listing of the ``example/containers.py``:
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.. literalinclude:: ../../examples/miniapps/application-single-container/example/containers.py
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:language: python
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Main module
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-----------
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Listing of the ``example/__main__.py``:
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.. literalinclude:: ../../examples/miniapps/application-single-container/example/__main__.py
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:language: python
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Services
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--------
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Listing of the ``example/services.py``:
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.. literalinclude:: ../../examples/miniapps/application-single-container/example/services.py
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:language: python
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Configuration
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-------------
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Listing of the ``config.ini``:
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.. literalinclude:: ../../examples/miniapps/application-single-container/config.ini
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:language: ini
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Listing of the ``logging.ini``:
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.. literalinclude:: ../../examples/miniapps/application-single-container/logging.ini
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:language: ini
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Run the application
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-------------------
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You can find the source code and instructions for running on the `Github <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/application-single-container>`_.
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.. disqus::
|
Before Width: | Height: | Size: 66 KiB After Width: | Height: | Size: 66 KiB |
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@ -10,5 +10,7 @@ Explore the examples to see the ``Dependency Injector`` in action.
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.. toctree::
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:maxdepth: 2
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services-single-container
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services-multiple-containers
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application-single-container
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application-multiple-containers
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.. disqus::
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|
|
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@ -1,73 +0,0 @@
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Services mini application example (multiple containers)
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=======================================================
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.. meta::
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:description: "Services miniapp" is an example mini application that
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consists from several services that have dependencies on
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some standard and 3rd-party libraries for logging,
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interaction with database and remote service via API.
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"Services miniapp" example demonstrates usage of
|
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Dependency Injector for creating inversion of control /
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dependency injection container.
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"Services miniapp" is an example mini application that consists from several
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services that have dependencies on some standard and 3rd-party libraries for
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logging, interaction with database and remote service calls via API.
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"Services miniapp" example demonstrates usage of
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:doc:`Dependency Injector <../index>` for creating IoC container.
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Instructions for running:
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.. code-block:: bash
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python run.py 1 secret photo.jpg
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Example application
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~~~~~~~~~~~~~~~~~~~
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Classes diagram:
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.. image:: /images/miniapps/services/classes.png
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:width: 100%
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:align: center
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Example application structure:
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.. code-block:: bash
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/example
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/__init__.py
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/main.py
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/services.py
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Listing of ``example/services.py``:
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.. literalinclude:: ../../examples/miniapps/services_v2/example/services.py
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:language: python
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Listing of ``example/main.py``:
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.. literalinclude:: ../../examples/miniapps/services_v2/example/main.py
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:language: python
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IoC container
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~~~~~~~~~~~~~
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Listing of ``container.py``:
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.. literalinclude:: ../../examples/miniapps/services_v2/container.py
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:language: python
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Run application
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~~~~~~~~~~~~~~~
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Listing of ``run.py``:
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.. literalinclude:: ../../examples/miniapps/services_v2/run.py
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:language: python
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.. disqus::
|
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@ -1,82 +0,0 @@
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Services mini application example (single container)
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====================================================
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.. meta::
|
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:description: "Services miniapp" is an example mini application that
|
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consists from several services that have dependencies on
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some standard and 3rd-party libraries for logging,
|
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interaction with database and remote service via API.
|
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"Services miniapp" example demonstrates usage of
|
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Dependency Injector for creating several inversion of control /
|
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dependency injection containers.
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|
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"Services" is an example mini application. It consists from several services that have
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dependencies on database & AWS S3.
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.. image:: images/services-miniapp.png
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:width: 100%
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:align: center
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Start from the scratch or jump to the section:
|
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|
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.. contents::
|
||||
:local:
|
||||
:backlinks: none
|
||||
|
||||
Application structure
|
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---------------------
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|
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Application consists from ``example`` package, several configuration files and ``requirements.txt``.
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|
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.. code-block:: bash
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|
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./
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├── example/
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│ ├── __init__.py
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│ ├── __main__.py
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│ ├── containers.py
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│ └── services.py
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├── config.ini
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├── logging.ini
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└── requirements.txt
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Container
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---------
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Listing of ``example/containers.py``:
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.. literalinclude:: ../../examples/miniapps/services-single-container/example/containers.py
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:language: python
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Listing of ``example/__main__.py``:
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.. literalinclude:: ../../examples/miniapps/services-single-container/example/__main__.py
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:language: python
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Services
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--------
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Listing of ``example/services.py``:
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.. literalinclude:: ../../examples/miniapps/services-single-container/example/services.py
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:language: python
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Configuration
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-------------
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Listing of ``config.ini``:
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.. literalinclude:: ../../examples/miniapps/services-single-container/config.ini
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:language: ini
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Listing of ``logging.ini``:
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.. literalinclude:: ../../examples/miniapps/services-single-container/logging.ini
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:language: ini
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Sources on Github
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-----------------
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To find the source code navigate to the `Github <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/services-single-container>`_.
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.. disqus::
|
|
@ -129,9 +129,8 @@ Contents
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:maxdepth: 2
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introduction/index
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main/installation
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tutorials/index
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examples/index
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tutorials/index
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providers/index
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containers/index
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examples-other/index
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|
|
|
@ -3,90 +3,90 @@ Dependency injection and inversion of control in Python
|
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.. meta::
|
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:keywords: Python,DI,Dependency injection,IoC,Inversion of Control
|
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:description: This article describes benefits of dependency injection and
|
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inversion of control for Python applications. Also it
|
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contains some Python examples that show how dependency
|
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injection and inversion could be implemented. In addition, it
|
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demonstrates usage of dependency injection framework,
|
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:description: This article describes benefits of dependency injection and
|
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inversion of control for Python applications. Also it
|
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contains some Python examples that show how dependency
|
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injection and inversion could be implemented. In addition, it
|
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demonstrates usage of dependency injection framework,
|
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IoC container and such popular design pattern as Factory.
|
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|
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History
|
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~~~~~~~
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Originally, dependency injection pattern got popular in languages with static
|
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typing, like Java. Dependency injection framework can
|
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Originally, dependency injection pattern got popular in languages with static
|
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typing, like Java. Dependency injection framework can
|
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significantly improve flexibility of the language with static typing. Also,
|
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implementation of dependency injection framework for language with static
|
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typing is not something that one can do shortly, it could be quite complex
|
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implementation of dependency injection framework for language with static
|
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typing is not something that one can do shortly, it could be quite complex
|
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thing to be done well.
|
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|
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While Python is very flexible interpreted language with dynamic typing, there
|
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is a meaning that dependency injection doesn't work for it as well, as it does
|
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for Java. Also there is a meaning that dependency injection framework is
|
||||
While Python is very flexible interpreted language with dynamic typing, there
|
||||
is a meaning that dependency injection doesn't work for it as well, as it does
|
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for Java. Also there is a meaning that dependency injection framework is
|
||||
something that Python developer would not ever need, cause dependency injection
|
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could be implemented easily using language fundamentals.
|
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|
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Discussion
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~~~~~~~~~~
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It is true.
|
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It is true.
|
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|
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Partly.
|
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|
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Dependency injection, as a software design pattern, has number of
|
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Dependency injection, as a software design pattern, has number of
|
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advantages that are common for each language (including Python):
|
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|
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+ Dependency Injection decreases coupling between a class and its dependency.
|
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+ Because dependency injection doesn't require any change in code behavior it
|
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can be applied to legacy code as a refactoring. The result is clients that
|
||||
are more independent and that are easier to unit test in isolation using
|
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stubs or mock objects that simulate other objects not under test. This ease
|
||||
of testing is often the first benefit noticed when using dependency
|
||||
+ Because dependency injection doesn't require any change in code behavior it
|
||||
can be applied to legacy code as a refactoring. The result is clients that
|
||||
are more independent and that are easier to unit test in isolation using
|
||||
stubs or mock objects that simulate other objects not under test. This ease
|
||||
of testing is often the first benefit noticed when using dependency
|
||||
injection.
|
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+ Dependency injection can be used to externalize a system's configuration
|
||||
details into configuration files allowing the system to be reconfigured
|
||||
without recompilation (rebuilding). Separate configurations can be written
|
||||
for different situations that require different implementations of
|
||||
+ Dependency injection can be used to externalize a system's configuration
|
||||
details into configuration files allowing the system to be reconfigured
|
||||
without recompilation (rebuilding). Separate configurations can be written
|
||||
for different situations that require different implementations of
|
||||
components. This includes, but is not limited to, testing.
|
||||
+ Reduction of boilerplate code in the application objects since all work to
|
||||
+ Reduction of boilerplate code in the application objects since all work to
|
||||
initialize or set up dependencies is handled by a provider component.
|
||||
+ Dependency injection allows a client to remove all knowledge of a concrete
|
||||
implementation that it needs to use. This helps isolate the client from the
|
||||
impact of design changes and defects. It promotes reusability, testability
|
||||
+ Dependency injection allows a client to remove all knowledge of a concrete
|
||||
implementation that it needs to use. This helps isolate the client from the
|
||||
impact of design changes and defects. It promotes reusability, testability
|
||||
and maintainability.
|
||||
+ Dependency injection allows a client the flexibility of being configurable.
|
||||
Only the client's behavior is fixed. The client may act on anything that
|
||||
+ Dependency injection allows a client the flexibility of being configurable.
|
||||
Only the client's behavior is fixed. The client may act on anything that
|
||||
supports the intrinsic interface the client expects.
|
||||
|
||||
.. note::
|
||||
|
||||
While improved testability is one the first benefits of using dependency
|
||||
injection, it could be easily overwhelmed by monkey-patching technique,
|
||||
that works absolutely great in Python (you can monkey-patch anything,
|
||||
anytime). At the same time, monkey-patching has nothing similar with
|
||||
other advantages defined above. Also monkey-patching technique is
|
||||
While improved testability is one the first benefits of using dependency
|
||||
injection, it could be easily overwhelmed by monkey-patching technique,
|
||||
that works absolutely great in Python (you can monkey-patch anything,
|
||||
anytime). At the same time, monkey-patching has nothing similar with
|
||||
other advantages defined above. Also monkey-patching technique is
|
||||
something that could be considered like too dirty to be used in production.
|
||||
|
||||
The complexity of dependency injection pattern implementation in Python is
|
||||
definitely quite lower than in other languages (even with dynamic typing).
|
||||
The complexity of dependency injection pattern implementation in Python is
|
||||
definitely quite lower than in other languages (even with dynamic typing).
|
||||
|
||||
.. note::
|
||||
.. note::
|
||||
|
||||
Low complexity of dependency injection pattern implementation in Python
|
||||
still means that some code should be written, reviewed, tested and
|
||||
Low complexity of dependency injection pattern implementation in Python
|
||||
still means that some code should be written, reviewed, tested and
|
||||
supported.
|
||||
|
||||
Talking about inversion of control, it is a software design principle that
|
||||
Talking about inversion of control, it is a software design principle that
|
||||
also works for each programming language, not depending on its typing type.
|
||||
|
||||
Inversion of control is used to increase modularity of the program and make
|
||||
Inversion of control is used to increase modularity of the program and make
|
||||
it extensible.
|
||||
|
||||
Main design purposes of using inversion of control are:
|
||||
|
||||
+ To decouple the execution of a task from implementation.
|
||||
+ To focus a module on the task it is designed for.
|
||||
+ To free modules from assumptions about how other systems do what they do and
|
||||
+ To free modules from assumptions about how other systems do what they do and
|
||||
instead rely on contracts.
|
||||
+ To prevent side effects when replacing a module.
|
||||
|
||||
|
@ -115,9 +115,9 @@ Next example demonstrates creation of several cars with different engines:
|
|||
:language: python
|
||||
|
||||
While previous example demonstrates advantages of dependency injection, there
|
||||
is a disadvantage demonstration as well - creation of car requires additional
|
||||
code for specification of dependencies. Nevertheless, this disadvantage could
|
||||
be easily avoided by using a dependency injection framework for creation of
|
||||
is a disadvantage demonstration as well - creation of car requires additional
|
||||
code for specification of dependencies. Nevertheless, this disadvantage could
|
||||
be easily avoided by using a dependency injection framework for creation of
|
||||
inversion of control container (IoC container).
|
||||
|
||||
Example of creation of several inversion of control containers (IoC containers)
|
||||
|
@ -131,18 +131,21 @@ What's next?
|
|||
|
||||
Choose one of the following as a next step:
|
||||
|
||||
+ Pass one of the dependency injection tutorials:
|
||||
+ :ref:`flask-tutorial`
|
||||
+ :ref:`aiohttp-tutorial`
|
||||
+ :ref:`asyncio-daemon-tutorial`
|
||||
+ :ref:`cli-tutorial`
|
||||
+ Know more about the :ref:`providers`
|
||||
+ Go to the :ref:`contents`
|
||||
- Look at application examples:
|
||||
- :ref:`application-single-container`
|
||||
- :ref:`application-multiple-containers`
|
||||
- Pass the tutorials:
|
||||
- :ref:`flask-tutorial`
|
||||
- :ref:`aiohttp-tutorial`
|
||||
- :ref:`asyncio-daemon-tutorial`
|
||||
- :ref:`cli-tutorial`
|
||||
- Know more about the :ref:`providers`
|
||||
- Go to the :ref:`contents`
|
||||
|
||||
Useful links
|
||||
~~~~~~~~~~~~
|
||||
|
||||
There are some useful links related to dependency injection design pattern
|
||||
There are some useful links related to dependency injection design pattern
|
||||
that could be used for further reading:
|
||||
|
||||
+ https://en.wikipedia.org/wiki/Dependency_injection
|
||||
|
|
|
@ -17,3 +17,4 @@ dependency injection pattern, inversion of control principle and
|
|||
what_is_di
|
||||
di_in_python
|
||||
key_features
|
||||
installation
|
||||
|
|
|
@ -31,7 +31,7 @@ Verification of currently installed version could be done using
|
|||
|
||||
>>> import dependency_injector
|
||||
>>> dependency_injector.__version__
|
||||
'3.15.2'
|
||||
'3.38.0'
|
||||
|
||||
.. _PyPi: https://pypi.org/project/dependency-injector/
|
||||
.. _GitHub: https://github.com/ets-labs/python-dependency-injector
|
|
@ -175,13 +175,16 @@ What's next?
|
|||
|
||||
Choose one of the following as a next step:
|
||||
|
||||
+ Pass one of the tutorials:
|
||||
+ :ref:`cli-tutorial`
|
||||
+ :ref:`flask-tutorial`
|
||||
+ :ref:`aiohttp-tutorial`
|
||||
+ :ref:`asyncio-daemon-tutorial`
|
||||
+ Know more about the :ref:`providers`
|
||||
+ Go to the :ref:`contents`
|
||||
- Look at application examples:
|
||||
- :ref:`application-single-container`
|
||||
- :ref:`application-multiple-containers`
|
||||
- Pass the tutorials:
|
||||
- :ref:`flask-tutorial`
|
||||
- :ref:`aiohttp-tutorial`
|
||||
- :ref:`asyncio-daemon-tutorial`
|
||||
- :ref:`cli-tutorial`
|
||||
- Know more about the :ref:`providers`
|
||||
- Go to the :ref:`contents`
|
||||
|
||||
.. disqus::
|
||||
|
||||
|
|
|
@ -1,5 +1,5 @@
|
|||
Services mini application example (multiple containers)
|
||||
=======================================================
|
||||
Application example (multiple containers)
|
||||
=========================================
|
||||
|
||||
Create virtual env:
|
||||
|
|
@ -1,5 +1,5 @@
|
|||
Services mini application example (single container)
|
||||
====================================================
|
||||
Application example (single container)
|
||||
======================================
|
||||
|
||||
Create virtual env:
|
||||
|
Loading…
Reference in New Issue
Block a user