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261 lines
8.7 KiB
ReStructuredText
.. figure:: https://raw.githubusercontent.com/wiki/ets-labs/python-dependency-injector/img/logo.svg
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:target: https://github.com/ets-labs/python-dependency-injector
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.. image:: https://img.shields.io/pypi/v/dependency_injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: Latest Version
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.. image:: https://img.shields.io/pypi/l/dependency_injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: License
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.. image:: https://img.shields.io/pypi/pyversions/dependency_injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: Supported Python versions
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.. image:: https://img.shields.io/pypi/implementation/dependency_injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: Supported Python implementations
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.. image:: https://pepy.tech/badge/dependency-injector
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:target: https://pepy.tech/project/dependency-injector
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:alt: Downloads
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.. image:: https://pepy.tech/badge/dependency-injector/month
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:target: https://pepy.tech/project/dependency-injector
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:alt: Downloads
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.. image:: https://pepy.tech/badge/dependency-injector/week
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:target: https://pepy.tech/project/dependency-injector
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:alt: Downloads
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.. image:: https://img.shields.io/pypi/wheel/dependency-injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: Wheel
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.. image:: https://travis-ci.org/ets-labs/python-dependency-injector.svg?branch=master
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:target: https://travis-ci.org/ets-labs/python-dependency-injector
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:alt: Build Status
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.. image:: http://readthedocs.org/projects/python-dependency-injector/badge/?version=latest
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:target: http://python-dependency-injector.ets-labs.org/
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:alt: Docs Status
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.. image:: https://coveralls.io/repos/github/ets-labs/python-dependency-injector/badge.svg?branch=master
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:target: https://coveralls.io/github/ets-labs/python-dependency-injector?branch=master
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:alt: Coverage Status
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What is ``Dependency Injector``?
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================================
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``Dependency Injector`` is a dependency injection framework for Python.
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The power of the framework is in its simplicity and straightforwardness.
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It stands on two principles:
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- Explicit is better than implicit (PEP20).
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- Do no magic to your code.
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How does it different from the other frameworks?
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- **No autowiring.** The framework does NOT do any autowiring / autoresolving of the dependencies. You need to specify everything explicitly. Because *"Explicit is better than implicit" (PEP20)*.
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- **Does not pollute your code** .Your application does NOT know and does NOT depend on the framework. No ``@inject`` decorators, annotations, patching or any other magic tricks.
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``Dependency Injector`` follows a simple contract with you:
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- You tell the framework how to build you code
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- The framework does it for you
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``Dependency Injector`` is a simple tool for the powerful concept.
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Why do I need it?
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=================
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``Dependency Injector`` helps you understand and change the structure of the application.
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With the ``Dependency Injector`` you keep **application structure in one place**.
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This place is called **the container**. You use the container to manage all the components of the
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application. All the component dependencies are defined explicitly. This provides the control on
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the application structure. It is **easy to understand and change** it.
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.. figure:: https://raw.githubusercontent.com/wiki/ets-labs/python-dependency-injector/img/di-map.svg
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:target: https://github.com/ets-labs/python-dependency-injector
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*The container is like a map of your application. You always know what depends on what.*
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``Flask`` + ``Dependency Injector`` example application container:
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.. code-block:: python
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from dependency_injector import containers, providers
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from dependency_injector.ext import flask
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from flask import Flask
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from flask_bootstrap import Bootstrap
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from github import Github
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from . import views, services
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class ApplicationContainer(containers.DeclarativeContainer):
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"""Application container."""
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app = flask.Application(Flask, __name__)
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bootstrap = flask.Extension(Bootstrap)
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config = providers.Configuration()
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github_client = providers.Factory(
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Github,
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login_or_token=config.github.auth_token,
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timeout=config.github.request_timeout,
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)
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search_service = providers.Factory(
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services.SearchService,
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github_client=github_client,
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)
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index_view = flask.View(
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views.index,
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search_service=search_service,
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default_query=config.search.default_query,
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default_limit=config.search.default_limit,
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)
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Running such container looks like this:
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.. code-block:: python
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from .containers import ApplicationContainer
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def create_app():
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"""Create and return Flask application."""
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container = ApplicationContainer()
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container.config.from_yaml('config.yml')
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container.config.github.auth_token.from_env('GITHUB_TOKEN')
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app = container.app()
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app.container = container
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bootstrap = container.bootstrap()
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bootstrap.init_app(app)
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app.add_url_rule('/', view_func=container.index_view.as_view())
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return app
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And testing looks like:
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.. code-block:: python
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from unittest import mock
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import pytest
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from github import Github
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from flask import url_for
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from .application import create_app
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@pytest.fixture
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def app():
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return create_app()
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def test_index(client, app):
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github_client_mock = mock.Mock(spec=Github)
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# Configure mock
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with app.container.github_client.override(github_client_mock):
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response = client.get(url_for('index'))
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assert response.status_code == 200
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# Do more asserts
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See complete example here - `Flask + Dependency Injector Example <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/ghnav-flask>`_
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How to install?
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---------------
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- The package is available on the `PyPi`_::
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pip install dependency-injector
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Where is the docs?
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------------------
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- The documentation is available on the `Read The Docs <http://python-dependency-injector.ets-labs.org/>`_
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Frequently asked questions
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--------------------------
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What is the dependency injection?
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- dependency injection is a principle that decreases coupling and increases cohesion
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Why should I do the dependency injection?
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- your code becomes more flexible, testable and clear
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- you have no problems when you need to understand how it works or change it 😎
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How do I start doing the dependency injection?
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- you start writing the code following the dependency injection principle
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- you register all of your application components and their dependencies in the container
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- when you need a component, you get it from the container
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Why do I need a framework for this?
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- you need the framework for this to not create it by your own
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- this framework gives you the container and the providers
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- the container is like a dictionary with the batteries 🔋
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- the providers manage the lifetime of your components, you will need factories, singletons, smart config object etc
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What price do I pay and what do I get?
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- you need to explicitly specify the dependencies in the container
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- it will be extra work in the beginning
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- it will payoff when project grows or in two weeks 😊 (when you forget what project was about)
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What features does the framework have?
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- building objects graph
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- smart configuration object
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- providers: factory, singleton, thread locals registers, etc
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- positional and keyword context injections
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- overriding of the objects in any part of the graph
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What features the framework does NOT have?
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- auto wiring / auto resolving of the dependencies
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- the annotations and ``@inject``-like decorators
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Have a question?
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----------------
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- Open a `Github Issue <https://github.com/ets-labs/python-dependency-injector/issues>`_
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Found a bug?
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------------
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- Open a `Github Issue <https://github.com/ets-labs/python-dependency-injector/issues>`_
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Want to help?
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-------------
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- |star| Star the ``Dependency Injector`` on the `Github <https://github.com/ets-labs/python-dependency-injector/>`_
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- |new| Start a new project with the ``Dependency Injector``
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- |tell| Tell your friend about the ``Dependency Injector``
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Want to contribute?
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-------------------
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- |fork| Fork the project
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- |pull| Open a pull request to the ``develop`` branch
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.. _PyPi: https://pypi.org/project/dependency-injector/
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.. |star| unicode:: U+2B50 U+FE0F .. star sign1
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.. |new| unicode:: U+1F195 .. new sign
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.. |tell| unicode:: U+1F4AC .. tell sign
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.. |fork| unicode:: U+1F500 .. fork sign
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.. |pull| unicode:: U+2B05 U+FE0F .. pull sign
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