256 lines
5.3 KiB
Markdown
256 lines
5.3 KiB
Markdown
Flask 备忘清单
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===
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本清单对 Flask 的入门进行了简要的概述，以及其常用示例。需要有 `HTML` 和 `Python` 基础。
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入门
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-----
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### 相关链接
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- [HTML](https://developer.mozilla.org/en-US/docs/Web/HTML) _(developer.mozilla.org)_
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- [Python](https://www.python.org/) _(python.org)_
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- [Flask](https://flask.palletsprojects.com/) _(flask.palletsprojects.com)_
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- [Python 备忘清单](./python.md) _(jaywcjlove.github.io)_
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### Hello World
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<!--rehype:wrap-class=row-span-2-->
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#### hello.py
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```python
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# 导入 Flask 类
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from flask import Flask
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# 创建应用实例
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app = Flask(__name__) # 'Flask' 参数是 应用程序模块 或 包 的名称
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# __name__是适用于大多数情况的便捷快捷方式
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# 路由 (装饰器)
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@app.route('/') # route()装饰器告诉 Flask 什么路径触发下面的功能
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def hello():
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# 该函数返回我们想要在浏览器中显示的消息内容
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return 'Hello World!'
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# 默认类型 HTML, 因此字符串中的 HTML 将被浏览器渲染
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# 启动服务
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if __name__ == '__main__':
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app.run()
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```
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### 运行 `hello.py` 程序
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<!--rehype:wrap-class=row-span-2-->
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```shell
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$ python hello.py
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* Serving Flask app 'hello'
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* Running on http://127.0.0.1:5000
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* Press CTRL+C to quit
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```
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#### 或
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```shell
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$ flask --app hello run
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* Serving Flask app 'hello'
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* Running on http://127.0.0.1:5000
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* Press CTRL+C to quit
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$ flask run --host=0.0.0.0
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```
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启用调试模式，使用 `--debug` 选项
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```bash
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$ flask --app hello --debug run
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```
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### HTML 转义
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```py
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from markupsafe import escape
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@app.route("/<name>")
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def hello(name):
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return f"Hello, {escape(name)}!"
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```
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### 路由
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```py
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@app.route('/')
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def index():
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return 'Index Page'
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@app.route('/hello')
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def hello():
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return 'Hello, World'
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```
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### 变量规则
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<!--rehype:wrap-class=row-span-2-->
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```py
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from markupsafe import escape
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@app.route('/user/<username>')
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def show_user_profile(username):
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# 显示该用户的用户个人资料
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return f'User {escape(username)}'
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@app.route('/post/<int:post_id>')
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def show_post(post_id):
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# 显示给定id的帖子，id是一个整数
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return f'Post {post_id}'
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@app.route('/path/<path:subpath>')
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def show_subpath(subpath):
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# 在 /path/ 之后显示子路径
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return f'Subpath {escape(subpath)}'
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```
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转换器类型：
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:-- | --
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:-- | --
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`string` | （默认）接受任何没有斜杠的文本
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`int` | 接受正整数
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`float` | 接受正浮点值
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`path` | 像字符串但也接受斜线
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`uuid` | 接受 UUID 字符串
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### 唯一 URL / 重定向行为
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```py
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@app.route('/projects/')
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def projects():
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return 'The project page'
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@app.route('/about')
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def about():
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return 'The about page'
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```
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项目端点的规范 `URL` 有一个尾部斜杠。它类似于文件系统中的文件夹。如果您访问没有尾部斜杠 (`/projects`) 的 `URL`，`Flask` 会将您重定向到带有尾部斜杠 (`/projects/`) 的规范 `URL`
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### URL 建设
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```py
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from flask import url_for
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@app.route('/')
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def index():
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return 'index'
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@app.route('/login')
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def login():
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return 'login'
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@app.route('/user/<username>')
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def profile(username):
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return f'{username}\'s profile'
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with app.test_request_context():
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print(url_for('index'))
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print(url_for('login'))
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print(url_for('login', next='/'))
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print(url_for('profile', username='John Doe'))
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```
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### HTTP 方法
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默认路由仅响应 `GET` 请求。可以使用 `route()` 装饰器的方法参数来处理不同的 `HTTP` 方法
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```py
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from flask import request
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@app.route('/login',methods=['GET','POST'])
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def login():
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if request.method == 'POST':
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return do_the_login()
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else:
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return show_the_login_form()
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```
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您还可以将不同方法的视图分成不同的函数。 `Flask` 为每个常见的 `HTTP` 方法提供了一种快捷方式，用于使用 `get()`、`post()` 等来装饰此类路由
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```py
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@app.get('/login')
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def login_get():
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return show_the_login_form()
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@app.post('/login')
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def login_post():
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return do_the_login()
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```
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### Blueprint
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创建蓝图Bp1
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```py
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from flask import Blueprint, abort, jsonify
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# 定义Bp1，并定义url前缀为/img
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Bp1 = Blueprint('imgBlue', __name__, template_folder='templates', url_prefix='/img')
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@Bp1.route('/getimg')
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def getImg():
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try:
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return jsonify(name="img", size="100KB")
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except Exception as e:
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abort(e)
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```
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创建蓝图Bp2
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```py
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from flask import Blueprint, abort, jsonify
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# 定义Bp2，并定义url前缀为/video
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Bp2 = Blueprint('videoBlue', __name__, template_folder='templates', url_prefix='/video')
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@Bp2.route('/getvideo')
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def getvideo():
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try:
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return jsonify(name="video", size="100GB")
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except Exception as e:
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abort(e)
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```
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在flask app中引用蓝图Bp1和Bp2
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```py
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from flask import Flask, jsonify
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from lantu.img import Bp1
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from lantu.video import Bp2
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app = Flask(__name__)
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# 注册蓝图到app
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app.register_blueprint(Bp1)
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app.register_blueprint(Bp2)
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@app.route('/')
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def index():
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return jsonify(name='phyger')
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if __name__ == '__main__':
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app.run(host="127.0.0.1", debug=True)
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```
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简单测试
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```bash
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curl http://127.0.0.1:5000/
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>> {"name":"phyger"}
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curl http://127.0.0.1:5000/img/getimg
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>> {"name": "img", "size": "100KB"}
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curl http://127.0.0.1:5000/video/getvideo
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>> {"name": "video", "size": "100GB"}
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```
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