mirror of
https://github.com/ets-labs/python-dependency-injector.git
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866 lines
22 KiB
ReStructuredText
866 lines
22 KiB
ReStructuredText
.. _aiohttp-tutorial:
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Aiohttp tutorial
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================
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.. meta::
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:keywords: Python,Aiohttp,Tutorial,Education,Web,API,REST API,Example,DI,Dependency injection,
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IoC,Inversion of control,Refactoring,Tests,Unit tests,Pytest,py.test,Bootstrap,
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HTML,CSS
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:description: This tutorial shows how to build an aiohttp application following the dependency
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injection principle. You will create the REST API application, connect to the
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Giphy API, cover it with the unit test and make some refactoring.
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This tutorial shows how to build an ``aiohttp`` REST API application following the dependency
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injection principle.
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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 complete project on the
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`Github <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/aiohttp>`_.
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What are we going to build?
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---------------------------
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.. image:: https://media.giphy.com/media/apvx5lPCPsjN6/source.gif
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We will build a REST API application that searches for funny GIFs on the `Giphy <https://giphy.com/>`_.
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Let's call it Giphy Navigator.
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How does Giphy Navigator work?
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- Client sends a request specifying the search query and the number of results.
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- Giphy Navigator returns a response in json format.
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- The response contains:
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- the search query
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- the limit number
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- the list of gif urls
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Example response:
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.. code-block:: json
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{
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"query": "Dependency Injector",
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"limit": 10,
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"gifs": [
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{
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"url": "https://giphy.com/gifs/boxes-dependent-swbf2-6Eo7KzABxgJMY"
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},
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{
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"url": "https://giphy.com/gifs/depends-J56qCcOhk6hKE"
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},
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{
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"url": "https://giphy.com/gifs/web-series-ccstudios-bro-dependent-1lhU8KAVwmVVu"
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},
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{
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"url": "https://giphy.com/gifs/TheBoysTV-friends-friend-weneedeachother-XxR9qcIwcf5Jq404Sx"
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},
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{
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"url": "https://giphy.com/gifs/netflix-a-series-of-unfortunate-events-asoue-9rgeQXbwoK53pcxn7f"
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},
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{
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"url": "https://giphy.com/gifs/black-and-white-sad-skins-Hs4YzLs2zJuLu"
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},
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{
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"url": "https://giphy.com/gifs/always-there-for-you-i-am-here-PlayjhCco9jHBYrd9w"
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},
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{
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"url": "https://giphy.com/gifs/stream-famous-dollar-YT2dvOByEwXCdoYiA1"
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},
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{
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"url": "https://giphy.com/gifs/i-love-you-there-for-am-1BhGzgpZXYWwWMAGB1"
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},
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{
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"url": "https://giphy.com/gifs/life-like-twerk-9hlnWxjHqmH28"
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}
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]
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}
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The task is naive and that's exactly what we need for the tutorial.
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Prepare the environment
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-----------------------
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Let's create the environment for the project.
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First we need to create a project folder:
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.. code-block:: bash
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mkdir giphynav-aiohttp-tutorial
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cd giphynav-aiohttp-tutorial
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Now let's create and activate virtual environment:
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.. code-block:: bash
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python3 -m venv venv
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. venv/bin/activate
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Environment is ready and now we're going to create the layout of the project.
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Project layout
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--------------
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Create next structure in the current directory. All files should be empty. That's ok for now.
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Initial project layout::
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./
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├── giphynavigator/
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│ ├── __init__.py
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│ ├── application.py
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│ ├── containers.py
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│ └── handlers.py
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├── venv/
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└── requirements.txt
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Install the requirements
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------------------------
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Now it's time to install the project requirements. We will use next packages:
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- ``dependency-injector`` - the dependency injection framework
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- ``aiohttp`` - the web framework
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- ``aiohttp-devtools`` - the helper library that will provide a development server with live
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reloading
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- ``pyyaml`` - the YAML files parsing library, used for the reading of the configuration files
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- ``pytest-aiohttp`` - the helper library for the testing of the ``aiohttp`` application
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- ``pytest-cov`` - the helper library for measuring the test coverage
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Put next lines into the ``requirements.txt`` file:
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.. code-block:: bash
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dependency-injector
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aiohttp
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aiohttp-devtools
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pyyaml
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pytest-aiohttp
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pytest-cov
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and run next in the terminal:
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.. code-block:: bash
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pip install -r requirements.txt
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Let's also install the ``httpie``. It is a user-friendly command-line HTTP client for the API era.
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We will use it for the manual testing.
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Run the command in the terminal:
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.. code-block:: bash
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pip install httpie
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The requirements are setup. Now we will build a minimal application.
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Minimal application
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-------------------
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In this section we will build a minimal application. It will have an endpoint that
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will answer our requests in json format. There will be no payload for now.
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Edit ``handlers.py``:
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.. code-block:: python
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"""Handlers module."""
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from aiohttp import web
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async def index(request: web.Request) -> web.Response:
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query = request.query.get("query", "Dependency Injector")
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limit = int(request.query.get("limit", 10))
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gifs = []
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return web.json_response(
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{
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"query": query,
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"limit": limit,
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"gifs": gifs,
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},
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)
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Now let's create a container. Container will keep all of the application components and their dependencies.
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Edit ``containers.py``:
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.. code-block:: python
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"""Containers module."""
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from dependency_injector import containers
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class Container(containers.DeclarativeContainer):
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...
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Container is empty for now. We will add the providers in the following sections.
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Finally we need to create ``aiohttp`` application factory. It will create and configure container
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and ``web.Application``. It is traditionally called ``create_app()``.
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We will assign ``index`` handler to handle user requests to the root ``/`` of our web application.
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Put next into the ``application.py``:
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.. code-block:: python
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"""Application module."""
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from aiohttp import web
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from .containers import Container
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from . import handlers
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def create_app() -> web.Application:
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container = Container()
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app = web.Application()
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app.container = container
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app.add_routes([
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web.get("/", handlers.index),
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])
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return app
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Now we're ready to run our application
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Do next in the terminal:
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.. code-block:: bash
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adev runserver giphynavigator/application.py --livereload
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The output should be something like:
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.. code-block:: bash
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[18:52:59] Starting aux server at http://localhost:8001 ◆
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[18:52:59] Starting dev server at http://localhost:8000 ●
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Let's check that it works. Open another terminal session and use ``httpie``:
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.. code-block:: bash
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http http://127.0.0.1:8000/
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You should see:
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.. code-block:: json
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HTTP/1.1 200 OK
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Content-Length: 844
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Content-Type: application/json; charset=utf-8
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Date: Wed, 29 Jul 2020 21:01:50 GMT
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Server: Python/3.9 aiohttp/3.6.2
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{
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"gifs": [],
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"limit": 10,
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"query": "Dependency Injector"
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}
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Minimal application is ready. Let's connect our application with the Giphy API.
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Giphy API client
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----------------
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In this section we will integrate our application with the Giphy API.
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We will create our own API client using ``aiohttp`` client.
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Create ``giphy.py`` module in the ``giphynavigator`` package:
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.. code-block:: bash
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:emphasize-lines: 6
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./
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├── giphynavigator/
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│ ├── __init__.py
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│ ├── application.py
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│ ├── containers.py
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│ ├── giphy.py
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│ └── handlers.py
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├── venv/
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└── requirements.txt
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and put next into it:
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.. code-block:: python
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"""Giphy client module."""
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from aiohttp import ClientSession, ClientTimeout
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class GiphyClient:
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API_URL = "https://api.giphy.com/v1"
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def __init__(self, api_key, timeout):
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self._api_key = api_key
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self._timeout = ClientTimeout(timeout)
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async def search(self, query, limit):
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"""Make search API call and return result."""
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url = f"{self.API_URL}/gifs/search"
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params = {
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"q": query,
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"api_key": self._api_key,
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"limit": limit,
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}
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async with ClientSession(timeout=self._timeout) as session:
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async with session.get(url, params=params) as response:
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if response.status != 200:
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response.raise_for_status()
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return await response.json()
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Now we need to add ``GiphyClient`` into the container. The ``GiphyClient`` has two dependencies
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that have to be injected: the API key and the request timeout. We will need to use two more
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providers from the ``dependency_injector.providers`` module:
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- ``Factory`` provider that will create the ``GiphyClient`` client.
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- ``Configuration`` provider that will provide the API key and the request timeout.
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Edit ``containers.py``:
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.. code-block:: python
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:emphasize-lines: 3-5,10-16
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"""Containers module."""
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from dependency_injector import containers, providers
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from . import giphy
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class Container(containers.DeclarativeContainer):
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config = providers.Configuration()
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giphy_client = providers.Factory(
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giphy.GiphyClient,
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api_key=config.giphy.api_key,
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timeout=config.giphy.request_timeout,
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)
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.. note::
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We have used the configuration value before it was defined. That's the principle how the
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``Configuration`` provider works.
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Use first, define later.
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Now let's add the configuration file.
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We will use YAML.
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Create an empty file ``config.yml`` in the root root of the project:
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.. code-block:: bash
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:emphasize-lines: 9
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./
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├── giphynavigator/
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│ ├── __init__.py
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│ ├── application.py
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│ ├── containers.py
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│ ├── giphy.py
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│ └── handlers.py
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├── venv/
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├── config.yml
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└── requirements.txt
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and put next into it:
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.. code-block:: yaml
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giphy:
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request_timeout: 10
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We will use an environment variable ``GIPHY_API_KEY`` to provide the API key.
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Now we need to edit ``create_app()`` to make two things when application starts:
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- Load the configuration file the ``config.yml``.
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- Load the API key from the ``GIPHY_API_KEY`` environment variable.
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Edit ``application.py``:
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.. code-block:: python
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:emphasize-lines: 11-12
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"""Application module."""
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from aiohttp import web
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from .containers import Container
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from . import handlers
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def create_app() -> web.Application:
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container = Container()
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container.config.from_yaml("config.yml")
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container.config.giphy.api_key.from_env("GIPHY_API_KEY")
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app = web.Application()
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app.container = container
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app.add_routes([
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web.get("/", handlers.index),
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])
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return app
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Now we need to create an API key and set it to the environment variable.
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As for now, don’t worry, just take this one:
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.. code-block:: bash
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export GIPHY_API_KEY=wBJ2wZG7SRqfrU9nPgPiWvORmloDyuL0
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.. note::
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To create your own Giphy API key follow this
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`guide <https://support.giphy.com/hc/en-us/articles/360020283431-Request-A-GIPHY-API-Key>`_.
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The Giphy API client and the configuration setup is done. Let's proceed to the search service.
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Search service
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--------------
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Now it's time to add the ``SearchService``. It will:
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- Perform the search.
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- Format result data.
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``SearchService`` will use ``GiphyClient``.
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Create ``services.py`` module in the ``giphynavigator`` package:
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.. code-block:: bash
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:emphasize-lines: 8
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./
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├── giphynavigator/
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│ ├── __init__.py
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│ ├── application.py
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│ ├── containers.py
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│ ├── giphy.py
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│ ├── handlers.py
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│ └── services.py
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├── venv/
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├── config.yml
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└── requirements.txt
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and put next into it:
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.. code-block:: python
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"""Services module."""
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from .giphy import GiphyClient
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class SearchService:
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def __init__(self, giphy_client: GiphyClient):
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self._giphy_client = giphy_client
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async def search(self, query, limit):
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"""Search for gifs and return formatted data."""
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if not query:
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return []
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result = await self._giphy_client.search(query, limit)
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return [{"url": gif["url"]} for gif in result["data"]]
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The ``SearchService`` has a dependency on the ``GiphyClient``. This dependency will be
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injected when we add ``SearchService`` to the container.
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Edit ``containers.py``:
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.. code-block:: python
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:emphasize-lines: 5,18-21
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"""Containers module."""
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from dependency_injector import containers, providers
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from . import giphy, services
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class Container(containers.DeclarativeContainer):
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config = providers.Configuration()
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giphy_client = providers.Factory(
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giphy.GiphyClient,
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api_key=config.giphy.api_key,
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timeout=config.giphy.request_timeout,
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)
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search_service = providers.Factory(
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services.SearchService,
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giphy_client=giphy_client,
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)
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The search service is ready. In next section we're going to put it to work.
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Make the search work
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--------------------
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Now we are ready to put the search into work. Let's inject ``SearchService`` into
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the ``index`` handler. We will use :ref:`wiring` feature.
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Edit ``handlers.py``:
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.. code-block:: python
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:emphasize-lines: 4-7,10-14,18
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"""Handlers module."""
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from aiohttp import web
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from dependency_injector.wiring import Provide, inject
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from .services import SearchService
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from .containers import Container
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@inject
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async def index(
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request: web.Request,
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search_service: SearchService = Provide[Container.search_service],
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) -> web.Response:
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query = request.query.get("query", "Dependency Injector")
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limit = int(request.query.get("limit", 10))
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gifs = await search_service.search(query, limit)
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return web.json_response(
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{
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"query": query,
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"limit": limit,
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"gifs": gifs,
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},
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)
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To make the injection work we need to wire the container instance with the ``handlers`` module.
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This needs to be done once. After it's done we can use ``Provide`` markers to specify as many
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injections as needed for any handler.
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Edit ``application.py``:
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.. code-block:: python
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:emphasize-lines: 13
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"""Application module."""
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|
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from aiohttp import web
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from .containers import Container
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from . import handlers
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|
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|
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def create_app() -> web.Application:
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container = Container()
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container.config.from_yaml("config.yml")
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container.config.giphy.api_key.from_env("GIPHY_API_KEY")
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container.wire(modules=[handlers])
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app = web.Application()
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app.container = container
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app.add_routes([
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web.get("/", handlers.index),
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])
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return app
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Make sure the app is running or use:
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|
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.. code-block:: bash
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adev runserver giphynavigator/application.py --livereload
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|
||
and make a request to the API in the terminal:
|
||
|
||
.. code-block:: bash
|
||
|
||
http http://localhost:8000/ query=="wow,it works" limit==5
|
||
|
||
You should see:
|
||
|
||
.. code-block:: json
|
||
|
||
HTTP/1.1 200 OK
|
||
Content-Length: 492
|
||
Content-Type: application/json; charset=utf-8
|
||
Date: Fri, 09 Oct 2020 01:35:48 GMT
|
||
Server: Python/3.9 aiohttp/3.6.2
|
||
|
||
{
|
||
"gifs": [
|
||
{
|
||
"url": "https://giphy.com/gifs/dollyparton-3xIVVMnZfG3KQ9v4Ye"
|
||
},
|
||
{
|
||
"url": "https://giphy.com/gifs/tennistv-unbelievable-disbelief-cant-believe-UWWJnhHHbpGvZOapEh"
|
||
},
|
||
{
|
||
"url": "https://giphy.com/gifs/discoverychannel-nugget-gold-rush-rick-ness-KGGPIlnC4hr4u2s3pY"
|
||
},
|
||
{
|
||
"url": "https://giphy.com/gifs/soulpancake-wow-work-xUe4HVXTPi0wQ2OAJC"
|
||
},
|
||
{
|
||
"url": "https://giphy.com/gifs/readingrainbow-teamwork-levar-burton-reading-rainbow-3o7qE1EaTWLQGDSabK"
|
||
}
|
||
],
|
||
"limit": 5,
|
||
"query": "wow,it works"
|
||
}
|
||
|
||
.. image:: https://media.giphy.com/media/3oxHQCI8tKXoeW4IBq/source.gif
|
||
|
||
The search works!
|
||
|
||
Make some refactoring
|
||
---------------------
|
||
|
||
Our ``index`` handler has two hardcoded config values:
|
||
|
||
- Default search query
|
||
- Default results limit
|
||
|
||
Let's make some refactoring. We will move these values to the config.
|
||
|
||
Edit ``handlers.py``:
|
||
|
||
.. code-block:: python
|
||
:emphasize-lines: 14-15,17-18
|
||
|
||
"""Handlers module."""
|
||
|
||
from aiohttp import web
|
||
from dependency_injector.wiring import Provide, inject
|
||
|
||
from .services import SearchService
|
||
from .containers import Container
|
||
|
||
|
||
@inject
|
||
async def index(
|
||
request: web.Request,
|
||
search_service: SearchService = Provide[Container.search_service],
|
||
default_query: str = Provide[Container.config.default.query],
|
||
default_limit: int = Provide[Container.config.default.limit.as_int()],
|
||
) -> web.Response:
|
||
query = request.query.get("query", default_query)
|
||
limit = int(request.query.get("limit", default_limit))
|
||
|
||
gifs = await search_service.search(query, limit)
|
||
|
||
return web.json_response(
|
||
{
|
||
"query": query,
|
||
"limit": limit,
|
||
"gifs": gifs,
|
||
},
|
||
)
|
||
|
||
Let's update the config.
|
||
|
||
Edit ``config.yml``:
|
||
|
||
.. code-block:: yaml
|
||
:emphasize-lines: 3-5
|
||
|
||
giphy:
|
||
request_timeout: 10
|
||
default:
|
||
query: "Dependency Injector"
|
||
limit: 10
|
||
|
||
The refactoring is done. We've made it cleaner - hardcoded values are now moved to the config.
|
||
|
||
Tests
|
||
-----
|
||
|
||
In this section we will add some tests.
|
||
|
||
Create ``tests.py`` module in the ``giphynavigator`` package:
|
||
|
||
.. code-block:: bash
|
||
:emphasize-lines: 9
|
||
|
||
./
|
||
├── giphynavigator/
|
||
│ ├── __init__.py
|
||
│ ├── application.py
|
||
│ ├── containers.py
|
||
│ ├── giphy.py
|
||
│ ├── handlers.py
|
||
│ ├── services.py
|
||
│ └── tests.py
|
||
├── venv/
|
||
├── config.yml
|
||
└── requirements.txt
|
||
|
||
and put next into it:
|
||
|
||
.. code-block:: python
|
||
:emphasize-lines: 32,59,73
|
||
|
||
"""Tests module."""
|
||
|
||
from unittest import mock
|
||
|
||
import pytest
|
||
|
||
from giphynavigator.application import create_app
|
||
from giphynavigator.giphy import GiphyClient
|
||
|
||
|
||
@pytest.fixture
|
||
def app():
|
||
app = create_app()
|
||
yield app
|
||
app.container.unwire()
|
||
|
||
|
||
@pytest.fixture
|
||
def client(app, aiohttp_client, loop):
|
||
return loop.run_until_complete(aiohttp_client(app))
|
||
|
||
|
||
async def test_index(client, app):
|
||
giphy_client_mock = mock.AsyncMock(spec=GiphyClient)
|
||
giphy_client_mock.search.return_value = {
|
||
"data": [
|
||
{"url": "https://giphy.com/gif1.gif"},
|
||
{"url": "https://giphy.com/gif2.gif"},
|
||
],
|
||
}
|
||
|
||
with app.container.giphy_client.override(giphy_client_mock):
|
||
response = await client.get(
|
||
"/",
|
||
params={
|
||
"query": "test",
|
||
"limit": 10,
|
||
},
|
||
)
|
||
|
||
assert response.status == 200
|
||
data = await response.json()
|
||
assert data == {
|
||
"query": "test",
|
||
"limit": 10,
|
||
"gifs": [
|
||
{"url": "https://giphy.com/gif1.gif"},
|
||
{"url": "https://giphy.com/gif2.gif"},
|
||
],
|
||
}
|
||
|
||
|
||
async def test_index_no_data(client, app):
|
||
giphy_client_mock = mock.AsyncMock(spec=GiphyClient)
|
||
giphy_client_mock.search.return_value = {
|
||
"data": [],
|
||
}
|
||
|
||
with app.container.giphy_client.override(giphy_client_mock):
|
||
response = await client.get("/")
|
||
|
||
assert response.status == 200
|
||
data = await response.json()
|
||
assert data["gifs"] == []
|
||
|
||
|
||
async def test_index_default_params(client, app):
|
||
giphy_client_mock = mock.AsyncMock(spec=GiphyClient)
|
||
giphy_client_mock.search.return_value = {
|
||
"data": [],
|
||
}
|
||
|
||
with app.container.giphy_client.override(giphy_client_mock):
|
||
response = await client.get("/")
|
||
|
||
assert response.status == 200
|
||
data = await response.json()
|
||
assert data["query"] == app.container.config.default.query()
|
||
assert data["limit"] == app.container.config.default.limit()
|
||
|
||
Now let's run it and check the coverage:
|
||
|
||
.. code-block:: bash
|
||
|
||
py.test giphynavigator/tests.py --cov=giphynavigator
|
||
|
||
You should see:
|
||
|
||
.. code-block::
|
||
|
||
platform darwin -- Python 3.9, pytest-5.4.3, py-1.9.0, pluggy-0.13.1
|
||
plugins: cov-2.10.0, aiohttp-0.3.0, asyncio-0.14.0
|
||
collected 3 items
|
||
|
||
giphynavigator/tests.py ... [100%]
|
||
|
||
---------- coverage: platform darwin, python 3.9 -----------
|
||
Name Stmts Miss Cover
|
||
---------------------------------------------------
|
||
giphynavigator/__init__.py 0 0 100%
|
||
giphynavigator/application.py 12 0 100%
|
||
giphynavigator/containers.py 6 0 100%
|
||
giphynavigator/giphy.py 14 9 36%
|
||
giphynavigator/handlers.py 10 0 100%
|
||
giphynavigator/services.py 9 1 89%
|
||
giphynavigator/tests.py 37 0 100%
|
||
---------------------------------------------------
|
||
TOTAL 88 10 89%
|
||
|
||
.. note::
|
||
|
||
Take a look at the highlights in the ``tests.py``.
|
||
|
||
It emphasizes the overriding of the ``GiphyClient``. The real API call are mocked.
|
||
|
||
Conclusion
|
||
----------
|
||
|
||
In this tutorial we've built an ``aiohttp`` REST API application following the dependency
|
||
injection principle.
|
||
We've used the ``Dependency Injector`` as a dependency injection framework.
|
||
|
||
:ref:`containers` and :ref:`providers` helped to specify how to assemble search service and
|
||
giphy client.
|
||
|
||
:ref:`configuration-provider` helped to deal with reading YAML file and environment variable.
|
||
|
||
We used :ref:`wiring` feature to inject the dependencies into the ``index()`` handler.
|
||
:ref:`provider-overriding` feature helped in testing.
|
||
|
||
We kept all the dependencies injected explicitly. This will help when you need to add or
|
||
change something in future.
|
||
|
||
You can find complete project on the
|
||
`Github <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/aiohttp>`_.
|
||
|
||
What's next?
|
||
|
||
- Look at the other :ref:`tutorials`
|
||
- Know more about the :ref:`providers`
|
||
- Go to the :ref:`contents`
|
||
|
||
.. disqus::
|