Flask Quick Start (3) - nature flask route

from flask import Flask
app = Flask(__name__)

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

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

From this simple code entry, to analyze what route@app.route('/')

route (): is a plus on the index () decorator

def route(self, rule, **options):  # rule：匹配规则，options参数字典
    def decorator(f):  
        endpoint = options.pop("endpoint", None)  # 如果option中有endpoint就取出，否则endpoint=None
        self.add_url_rule(rule, endpoint, f, **options)  # f就是装饰器装饰的视图函数 index
        return f
    return decorator

Obtain information:

(1) can be specified when the reference transmission route endpoint = '别名', the route to be taken Endpoint alias, as reverse analysis, will be described later again. None for the time did not pass.

(2) it is the implementation of a method of matching add_url_rule adding a predetermined correspondence relationship with the view route to function

add_url_rule (): matching a predetermined correspondence relationship with the view to add a function to route

@setupmethod
def add_url_rule(self,rule,endpoint=None,view_func=None,provide_automatic_options=None,**options):
    # 其中rule是必须要传入的，endpoint是别名，view_func是函数名
    if endpoint is None:
        endpoint = _endpoint_from_view_func(view_func)  # 如果没有别名就执行该函数，并且将视图函数当做参数传入了，稍后再看
    options["endpoint"] = endpoint
    methods = options.pop("methods", None)  # 如果options中有methods则取出，否则为methods = None
    
    # 如果methods为None的话，默认为view_func中的methods属性值，或者为('GET',)请求
    if methods is None:
        methods = getattr(view_func, "methods", None) or ("GET",)
    # 如果methods是字符串类型，string_types=>(str, unicode),则抛出异常
    if isinstance(methods, string_types):
        raise TypeError(
            "Allowed methods have to be iterables of strings, "
            'for example: @app.route(..., methods=["POST"])'
        )
    # 循环遍历methods,并转成大写、去重
    methods = set(item.upper() for item in methods)

    required_methods = set(getattr(view_func, "required_methods", ()))

    if provide_automatic_options is None:
        provide_automatic_options = getattr(
            view_func, "provide_automatic_options", None
        )

    if provide_automatic_options is None:
        if "OPTIONS" not in methods:
            provide_automatic_options = True
            required_methods.add("OPTIONS")
        else:
            provide_automatic_options = False

    methods |= required_methods

    rule = self.url_rule_class(rule, methods=methods, **options)
    rule.provide_automatic_options = provide_automatic_options

    self.url_map.add(rule)  # 添加匹配规则
    if view_func is not None:
        old_func = self.view_functions.get(endpoint)  # 默认self.view_functions={}，所以old_func=None
        if old_func is not None and old_func != view_func:
            raise AssertionError(
                "View function mapping is overwriting an "
                "existing endpoint function: %s" % endpoint
            )
        self.view_functions[endpoint] = view_func  # 将 endpoint 与 view_func 对应。{endpoint:view_func}

One can see the source code is not ignorant of the above, the relevant part of the code to add a comment. Obtain information:

(1) methods are defined in the view mode request function, if it is not specified the default mode is get

(2) methods transmission parameter is a string type can not pass, should be provided: methods = ( 'post',), parameters are case insensitive, i.e., 'post' and 'POST' can be passed

(3) a value corresponding to the function name endpoint, such as endpoint = 'xxx': it is equivalent to the view taken an alias index function. If there is no endpoint, perform _endpoint_from_view_func(view_func), endpoint = function name

def _endpoint_from_view_func(view_func):
    """Internal helper that returns the default endpoint for a given
    function.  This always is the function name.
    """
    assert view_func is not None, "expected view func if endpoint is not provided."
    return view_func.__name__  # 返回的就是函数名

to sum up:

(1) the routing is performed essentially add_url_rule functions, it is also possible to add the routing function byapp.add_url_rule('/',endpoint='xxx',view_func=index)

(2) endpoint: to specify an alias, you do not specify a function name

(3) methods: request to specify the view function, it is not specified default to get method

(4) url_for: do the reverse route resolution alias

from flask import Flask, request,redirect,url_for
app = Flask(__name__)
app.debug =True

# @app.route('/')
def index():
    return 'dasdk'
app.add_url_rule('/',endpoint='xxx',view_func=index)  # 用来绑定路由

@app.route('/login',methods=['post','get'])
def login():
    url = url_for('xxx')  # 反向路由解析，url此时指向index视图函数
    return redirect(url)

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