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[#]: via: (https://fedoramagazine.org/use-fastapi-to-build-web-services-in-python/)
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[#]: author: (Clément Verna https://fedoramagazine.org/author/cverna/)
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Use FastAPI to build web services in Python
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使用 Python FastAPI 构建 Web 服务
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======
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![][1]
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_[FastAPI][2]_ is a modern Python web framework that leverage the latest Python improvement in asyncio. In this article you will see how to set up a container based development environment and implement a small web service with FastAPI.
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[FastAPI][2] 是一个使用 Python 编写的 Web 框架，还应用了 Python asyncio 库中最新的优化。本文将会介绍如何搭建基于容器的开发环境，还会展示如何使用 FastAPI 实现一个小型 Web 服务。
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### Getting Started
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### 起步
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The development environment can be set up using the Fedora container image. The following Dockerfile prepares the container image with FastAPI, [Uvicorn][3] and [aiofiles][4].
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我们将使用 Fedora 作为基础镜像来搭建开发环境，并使用 Dockerfile 为镜像注入 FastAPI、[Uvicorn][3] 和 [aiofiles][4] 这几个包。
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```
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FROM fedora:32
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@ -27,7 +28,7 @@ WORKDIR /srv
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CMD ["uvicorn", "main:app", "--reload"]
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```
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After saving this Dockerfile in your working directory, build the container image using podman.
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在工作目录下保存 Dockerfile 之后，执行 `podman` 命令构建容器镜像。
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```
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$ podman build -t fastapi .
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@ -36,7 +37,7 @@ REPOSITORY TAG IMAGE ID CREATED SIZE
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localhost/fastapi latest 01e974cabe8b 18 seconds ago 326 MB
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```
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Now let’s create a basic FastAPI program and run it using that container image.
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下面我们可以开始创建一个简单的 FastAPI 应用程序，并通过容器镜像运行。
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```
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from fastapi import FastAPI
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@ -48,7 +49,7 @@ async def root():
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return {"message": "Hello Fedora Magazine!"}
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```
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Save that source code in a _main.py_ file and then run the following command to execute it:
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将上面的代码保存到 `main.py` 文件中，然后执行以下命令开始运行：
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```
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$ podman run --rm -v $PWD:/srv:z -p 8000:8000 --name fastapi -d fastapi
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@ -56,33 +57,31 @@ $ curl http://127.0.0.1:8000
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{"message":"Hello Fedora Magazine!"
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```
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You now have a running web service using FastAPI. Any changes to _main.py_ will be automatically reloaded. For example, try changing the “Hello Fedora Magazine!” message.
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这样，一个基于 FastAPI 的 Web 服务就跑起来了。由于指定了 `--reload` 参数，一旦 `main.py` 文件发生了改变，整个应用都会自动重新加载。你可以尝试将返回信息 `"Hello Fedora Magazine!"` 修改为其它内容，然后观察效果。
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To stop the application, run the following command.
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可以使用以下命令停止应用程序：
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```
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$ podman stop fastapi
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```
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### Building a small web service
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### 构建一个小型 Web 服务
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To really see the benefits of FastAPI and the performance improvement it brings ([see comparison][5] with other Python web frameworks), let’s build an application that manipulates some I/O. You can use the output of the _dnf history_ command as data for that application.
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接下来我们会构建一个需要 I/O 操作的应用程序，通过这个应用程序，我们可以看到 FastAPI 自身的特点，以及它在性能上有什么优势（可以在[这里][5]参考 FastAPI 和其它 Python Web 框架的对比）。为简单起见，我们直接使用 `dnf history` 命令的输出来作为这个应用程序使用的数据。
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First, save the output of that command in a file.
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首先将 `dnf history` 命令的输出保存到文件。
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```
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$ dnf history | tail --lines=+3 > history.txt
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```
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The command is using _tail_ to remove the headers of _dnf history_ which are not needed by the application. Each dnf transaction can be represented with the following information:
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在上面的命令中，我们使用 `tail` 去除了 `dnf history` 输出内容中无用的表头信息。剩余的每一条 `dnf` 事务都包括了以下信息：
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* id : number of the transaction (increments every time a new transaction is run)
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* command : the dnf command run during the transaction
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* date: the date and time the transaction happened
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* id：事务编号（每次运行一条新事务时该编号都会递增）
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* command：事务中运行的 `dnf` 命令
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* date：执行事务的日期和时间
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Next, modify the _main.py_ file to add that data structure to the application.
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然后修改 `main.py` 文件将相关的数据结构添加进去。
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```
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from fastapi import FastAPI
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@ -96,9 +95,9 @@ class DnfTransaction(BaseModel):
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date: str
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```
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FastAPI comes with the [pydantic][6] library which allow you to easily build data classes and benefit from type annotation to validate your data.
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FastAPI 自带的 [pydantic][6] 库让你可以轻松定义一个数据类，其中的类型注释对数据的验证也提供了方便。
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Now, continue building the application by adding a function that will read the data from the _history.txt_ file.
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再增加一个函数，用于从 `history.txt` 文件中读取数据。
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```
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import aiofiles
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@ -125,9 +124,9 @@ async def read_history():
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return transactions
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```
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This function makes use of the _[aiofiles][4]_ library which provides an asyncio API to manipulate files in Python. This means that opening and reading the file will not block other requests made to the server.
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这个函数中使用了 `aiofiles` 库，这个库提供了一个异步 API 来处理 Python 中的文件，因此打开文件或读取文件的时候不会阻塞其它对服务器的请求。
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Finally, change the root function to return the data stored in the transactions list.
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最后，修改 `root` 函数，让它返回事务列表中的数据。
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```
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@app.get("/")
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@ -135,7 +134,7 @@ async def read_root():
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return await read_history()
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```
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To see the output of the application, run the following command
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执行以下命令就可以看到应用程序的输出内容了。
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```
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$ curl http://127.0.0.1:8000 | python -m json.tool
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@ -159,23 +158,24 @@ $ curl http://127.0.0.1:8000 | python -m json.tool
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]
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```
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### Conclusion
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### 总结
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_FastAPI_ is gaining a lot a popularity in the Python web framework ecosystem because it offers a simple way to build web services using asyncio. You can find more information about _FastAPI_ in the [documentation][2].
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FastAPI 提供了一种使用 asyncio 构建 Web 服务的简单方法，因此它在 Python Web 框架的生态中日趋流行。要了解 FastAPI 的更多信息，欢迎查阅 [FastAPI 文档][2]。
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The code of this article is available in [this GitHub repository][7].
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本文中的代码可以在 [GitHub][7] 上找到。
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* * *
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_Photo by [Jan Kubita][8] on [Unsplash][9]._
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--------------------------------------------------------------------------------
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via: https://fedoramagazine.org/use-fastapi-to-build-web-services-in-python/
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作者：[Clément Verna][a]
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选题：[lujun9972][b]
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译者：[译者ID](https://github.com/译者ID)
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译者：[HankChow](https://github.com/HankChow)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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