Flask(视图函数四)

基于类的视图，可插拔视图

从Django学来的

好处：

类可以继承
代码可以复用

可以定义多种行为

from flask import Flask, request
from flask.views import View

app = Flask(__name__)


class UserView(View):
    methods = ['GET', 'POST']

    def get(self):
        return 'get'

    def post(self):
        return 'post'

    # 分配请求
    def dispatch_request(self):
        dispatch_pattern = {'GET': self.get, 'POST': self.post}
        method = request.method
        return dispatch_pattern.get(method)()


app.add_url_rule(
    '/user',
    view_func=UserView.as_view('user'),
    methods=["GET", "POST"]
)

if __name__ == '__main__':
    app.run(debug=True)

GET

装饰这个类视图

由于会被as_view转换，所以需要显式的装饰它

def log_time(f):
    def decorator(*args, **kwargs):
        print(time.time())
        return f(*args, **kwargs)

    return decorator


f = UserView.as_view('user')
log_time(f)

app.add_url_rule(
    '/user',
    view_func=f,
    methods=["GET", "POST"]
)

使用`MethodView`

from flask import Flask, request
from flask.views import View, MethodView

app = Flask(__name__)


class ProjectView(MethodView):
    def get(self):
        return 'get'

    def post(self):
        return 'post'


app.add_url_rule(
    '/project',
    view_func=ProjectView.as_view('project'),
    methods=["GET", "POST"]
)

if __name__ == '__main__':
    app.run(debug=True)

这个类就是继承了View然后重写了dispatch_request

def dispatch_request(self, *args, **kwargs):
    meth = getattr(self, request.method.lower(), None)

    # If the request method is HEAD and we don't have a handler for it
    # retry with GET.
    if meth is None and request.method == "HEAD":
        meth = getattr(self, "get", None)

    assert meth is not None, "Unimplemented method %r" % request.method
    return meth(*args, **kwargs)

相当于

class MethodView:
    def get(self):
        print('get')	
        return 'get'

    def post(self):
        print('post')
        return 'post'

    def dispatch_request(self):
        func = getattr(self, 'get', None)
        return func()


MethodView().dispatch_request()

func = getattr(self, 'get', None)

使用MethodView实现reful风格接口

from flask.views import MethodView
from flask import Flask

app = Flask(__name__)


class ProjectView(MethodView):
    def get(self, project_id):
        if project_id is None:
            return 'ALL projects'
        return f'get {project_id}'

    def post(self, project_id):
        return f'post {project_id}'

    def put(self, project_id):
        return f'put {project_id}'

    def delete(self, project_id):
        return f'delete {project_id}'


f = ProjectView.as_view('projects')
app.add_url_rule('/projects/<project_id>', view_func=f, methods=['GET', 'POST', 'PUT', 'DELETE'])
app.add_url_rule('/projects/', defaults={"project_id": None}, view_func=f, methods=['GET'])
if __name__ == '__main__':
    app.run()

request获取请求数据

get

1	get_data = request.args

表单

1	form_data = request.form

json

1	json_data = request.json

file

1	file_data = request.files

上传文件的代码

html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/uploads" method="post" enctype="multipart/form-data">
    <input type="file" name="pic">
    <input type="submit">
</form>
</body>
</html>

python代码

# -*- encoding: utf-8 -*-
"""
@File    : homework.py
@Time    : 2020/6/16 7:18 上午
@Author  : zhongxin
@Email   : 490336534@qq.com
"""
import os
import time

from flask import Flask, request, render_template, redirect

app = Flask(__name__)
print(app.instance_path)
print(app.root_path)
print(app.static_folder)


@app.route('/')
def index():
    return render_template('index.html')


@app.route('/uploads', methods=['POST'])
def upload():
    file = request.files.get('pic')
    if not file:
        return render_template('index.html')
    file_name = time.strftime('%Y-%m-%d-%H-%M-%S') + file.filename
    file_url = f'/static/{file_name}'
    file.save(os.path.join(
        app.root_path,
        app.static_folder,
        file_name
    ))
    return redirect(file_url)


if __name__ == '__main__':
    app.run()

上传文件

Flask(视图函数 四)

基于类的视图，可插拔视图

装饰这个类视图

使用MethodView

使用MethodView实现reful风格接口

request获取请求数据

get

表单

json

file

上传文件的代码

html

python代码

Flask(视图函数四)

使用`MethodView`