python - Flask里endpoint view function 路由等概念如何理解

Answer 1

Concept

• Routing rule table url_map._rules

  • Rule One of the rules

    • Function / view function - A view function that handles a certain endpoint/path. It can be simply understood as a function that processes a certain/group of URLs.

    • Endpoint - flask internal identifier

    • Others/Rule rule converters, methods and the like

Process:

1. Create Rule/path

2. Assign endpoint to Rule/path

3. Specify view function for Rule/path.

Key points

1. When a request comes in, it is located inside the app based on rule/path, that is to say: rule/path 来定位到 app 内部的，也就是说：

   • 当用户请求 /a 时，会调用 /a 条路由规则指定的视图函数来处理这个请求。

   • 同理，/users/<string:username> 也是一样。

2. 在 flask 的 url_map 路由表中，rule/path 和 endpoint 在路由规则表里都是唯一的

   • 尤其是 endpoint，如果重复会报错。

   • rule/path，虽然可以重复，但其实只有第一条会生效。

3. 如果开发者没有在 @app.route 装饰器或 app.add_url_rule() 函数调用处指定 endpoint 的话，flask 会为这条 Rule 规则 指定一个默认的 endpoint，即这个 view function 的名字。

关系

• 一个 view function，可以有多个 endpoint、rule。是个一对多的关系。

• 反过来，一个 endpoint，只能有一个 rule, 也只能有一个 view function。

答案与解释

现在，回头来看题主的疑问。

1 . 『路由的内部名字是什么？』

名字是：index。

在题主所说的下面的这个视图中，endpoint/路由规则表内部名称是 index，因为并未在 @app.route 函数调用中显式指定 endpoint。

@app.route('/', methods=['GET', 'POST']) 
    def index():
        form = NameForm()
        if form.validate_on_submit():
            session['name'] = form.name.data
            return redirect(url_for('index'))
        return render_template('index.html', form=form, name=session.get('name'))

2 . 『endpoint 是一个附加到视图函数的名称，所以，endpoint名就是视图函数的名称么？』

不是。正如上面 重点 处所说，如果没有显式指定 endpoint，flask 会将视图函数的名称也即此处的 index 当作此路由规则的 endpoint。

3 . 『为什么需要endpoint参数的时候，需要把视图函数的名称传进去？』

并非是 视图函数的名称，其实是 endpoint

When the user requests /a, the view function specified by the /a routing rule will be called to handle the request.

🎜🎜Similarly, the same goes for /users/<string:username>. 🎜🎜 🎜 🎜 🎜 🎜In flask's url_map routing table, rule/path and endpoint are unique in the routing rule table🎜 🎜 🎜🎜Especially endpoint, if it is repeated, an error will be reported. 🎜🎜 🎜🎜rule/path, although it can be repeated, only the first one will take effect. 🎜🎜 🎜 🎜 🎜🎜If the developer does not specify an endpoint in the @app.route decorator or app.add_url_rule() function call, flask will specify it for this 🎜Rule rule🎜 A default endpoint, which is the name of this view function. 🎜🎜 🎜 🎜Relationship🎜 🎜 🎜🎜A view function can have multiple endpoint and rule. It is a one-to-many relationship. 🎜🎜 🎜🎜Conversely, an endpoint can only have one rule, and can only have one view function. 🎜🎜 🎜 🎜Answers and Explanations🎜 🎜Now, let’s look back at the subject’s question. 🎜 🎜1. "What is the internal name of the route?" 』🎜 🎜The name is: index. 🎜 🎜In the view below mentioned by the questioner, the internal name of the endpoint/routing rule table is index, because it is not displayed in the @app.route function call🎜 The formula 🎜 specifies the endpoint. 🎜

#!/usr/bin/env python3
# coding=utf-8
import flask

app = flask.Flask(__name__)


@app.route('/', endpoint="home")
def amihome():
    '''
    请尝试以  `/` 和 `/shajiquan` 两个路径来访问；
    '''
    return "View function: {view}. Endpoint: {endpoint}".format(view="amihome", endpoint=flask.request.endpoint)


# 给 app 添加一条 url rule, 指定 rule, endpoint, 但不指定 view function.
app.add_url_rule(rule='/shajiquan', endpoint="shajiquan", methods=["GET", "DELETE"])
# 为 endpoint="shajiquan" 指定 view function
app.view_functions['shajiquan'] = amihome


@app.route('/')
def miao():
    return "wu at: {}".format(flask.request.endpoint)


# 尝试取消注释
# app.view_functions['home'] = miao


if __name__ == '__main__':
    app.run(debug=True, port=8964)

🎜2. 『Endpoint is a name attached to the view function, so is the endpoint name the name of the view function? 』🎜 🎜No. As mentioned in the 🎜Key Point🎜 above, if there is no 🎜explicit🎜specify the endpoint, flask will use the name of the view function, which is the index here, as the endpoint of this routing rule. 🎜 🎜3. "Why do we need to pass the name of the view function when we need the endpoint parameter?" 』🎜 🎜 is not the name of the 🎜view function🎜, but actually the name of endpoint. It just happens that at some point, the name of endpoint is the same as the name of the 🎜view function🎜. 🎜 🎜Demo🎜 rrreee

Answer 2

Look at this piece of code

class LoginView(views.MethodView):
    def get(self):
        pass
    def post(self):
        pass
        
app.add_url_rule(
    '/login/',
    endpoint='login',
    view_func=LoginView.as_view(b'login'),
    methods=['POST', 'GET']
)

We can use classes to write routes. Flask abstracts this writing method into decorators, function name = endpoint

Answer 3

I don’t know if this answer can help you understand the endpoint http://segmentfault.com/q/1010000002980493