flask框架——路由系统route转换成add_url_rule及源码分析

Posted 2020-11-29 wangcuican

这节我们不用@app.route来写路由，而是通过add_url_rule

典型写法  （<int:nid>传递int类型参数，endpoint是取别名）

@app.route(‘/detail/<int:nid>‘,methods=[‘GET‘],endpoint=‘detail‘)

默认转换器

DEFAULT_CONVERTERS = {
    ‘default‘:          UnicodeConverter,
    ‘string‘:           UnicodeConverter,
    ‘any‘:              AnyConverter,
    ‘path‘:             PathConverter,
    ‘int‘:              IntegerConverter,
    ‘float‘:            FloatConverter,
    ‘uuid‘:             UUIDConverter,
}

路由系统本质（源码分析）

从@app.route的route入手

源码app.py （从下面的源码可以看出route本质就是add_url_rule.这里的self就是实例化对象，也就是之前的app）

    def route(self, rule, **options)：

        def decorator(f):
            endpoint = options.pop("endpoint", None)
            self.add_url_rule(rule, endpoint, f, **options)
            return f

        return decorator

然后跳转到add_url_rule中

@setupmethod
    def add_url_rule(
        self,
        rule,  #视图函数路由
        endpoint=None,  #取别名（非必填）
        view_func=None,  #这个就是上一个跳转过来的f,就是视图函数名（必填）
        provide_automatic_options=None,
        **options
    ):
   
        if endpoint is None:  #如果endpoint(别名)没填，就进入_endpoint_from_view_func看看
            endpoint = _endpoint_from_view_func(view_func)
        options["endpoint"] = endpoint
        methods = options.pop("methods", None)

        if methods is None:
            methods = getattr(view_func, "methods", None) or ("GET",)
        if isinstance(methods, string_types):
            raise TypeError(
                "Allowed methods have to be iterables of strings, "
                ‘for example: @app.route(..., methods=["POST"])‘
            )
        methods = set(item.upper() for item in methods)

        # Methods that should always be added
        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

        # Add the required methods now.
        methods |= required_methods

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

        self.url_map.add(rule)
        if view_func is not None:
            old_func = self.view_functions.get(endpoint)
            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

进入_endpoint_from_view_func看看是怎么取别名的 ()

assert view_func is not None, "expected view func if endpoint is not provided."
return view_func.__name__

第一句话是永远不是执行的，看第二句，取得是视图函数名，这里就是login

取别名使用方法（url_for）： 访问login路径,返回123

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

def index():
    return ‘123‘
app.add_url_rule(‘/index‘,view_func=index,endpoint=‘sb‘,methods=[‘POST‘,"GET"])


def login():
    real_url=url_for("sb")
    return real_url
app.add_url_rule(‘/login‘,view_func=index,methods=[‘POST‘,"GET"])

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

 

add_url_rule参数总结：

rule:必填参数，就是跳转路由
endpoint:非必填参数，如果不填就是视图函数名。如果设置了endpoint，就在视图函数中通过url_for使用，不能设置重复
view_func:也就是请求该路由时，要相应的函数
methods:设置请求方式，默认是get请求

总结代码示例：

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

def login(nid):
    print(type(nid),nid)
    return "ojbk_login"
app.add_url_rule(‘/login/<string:nid>‘,view_func=login,endpoint="sb",methods=[‘POST‘,"GET"])

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

也可以设置有名参数：添加数据类型的有名参数，通过视图函数传递参数