f'lask源码

上下文本质

- 当请求过来后,将请求相关数据添加到 Local()类中

{

线程或协程唯一标识:{"stack":[request]},

线程或协程唯一标识:{"stack":[]},

线程或协程唯一标识:{"stack":[]}

}

- 以后使用时去读取

- 请求完成之后,将request从列表中移除

Flask源码

from flask import Flask,session,request

app = Flask(__name__)

@app.route("/login",methods=["GET","POST"])

def login():

return "index"

if __name__ == '__main__':

#app.__call__()

app.run()

1. 执行app.__call__方法

def __call__(self, environ, start_response):

        return self.wsgi_app(environ, start_response)

2. 执行wsgi_app方法

def wsgi_app(self, environ, start_response):

    ctx = self.request_context(environ)

    ctx.push()

    response = self.full_dispatch_request()

2.1 生成RequestContext()对象封装请求相关的数据(request,session)

1	`ctx = self.request_context(environ)`

def request_context(self, environ):

    return RequestContext(self, environ)

class RequestContext(object):

    def __init__(self, app, environ, request=None):

           self.app = app

           if request is None:

            request = app.request_class(environ)

           self.request = request

2.2 将用户请求数据封装到Local()类中

1	`ctx.push()`

def push(self):

    from .globals import _request_ctx_stack

    #将请求数据封装到Local()类

    _request_ctx_stack.push(self)

    #处理session

    self.session = self.app.open_session(self.request)

    if self.session is None:

        self.session = self.app.make_null_session()

2.2.1 导入 _request_ctx_stack对象内部会自动生成 { 线程或协程唯一标识:{"stack":[]} } 格式

1	`from` `.globals import _request_ctx_stack`

class Local(object):

    def __init__(self):

        object.__setattr__(self, '__storage__', {})

        object.__setattr__(self, '__ident_func__', get_ident)

    def __setattr__(self, name, value):

        ident = self.__ident_func__()

        storage = self.__storage__

        try:

            storage[ident][name] = value

        except KeyError:

            storage[ident] = {name: value}

class LocalStack(object):

    def __init__(self):

        self._local = Local()

    def push(self, obj):

        rv = getattr(self._local, 'stack', None)

        if rv is None:

            self._local.stack = rv = []

        rv.append(obj)

        return rv

_request_ctx_stack = LocalStack()

2.2.2 执行_request_ctx_stack对象push方法触发Local类的__setattr__方法生成 { 线程或协程唯一标识:{"stack":[ RequestContext对象 ]} }

1	`_request_ctx_stack.push(self)`

class Local(object):

    def __setattr__(self, name, value):

        ident = self.__ident_func__()

        storage = self.__storage__

        try:

            storage[ident][name] = value

        except KeyError:

            storage[ident] = {name: value}

class LocalStack(object):

    def push(self, obj):

        """Pushes a new item to the stack"""

        rv = getattr(self._local, 'stack', None)

        if rv is None:

            self._local.stack = rv = []

        rv.append(obj)

        return rv

_request_ctx_stack = LocalStack()

2.2.3 self.session重新赋值

RequestContext类的 self.session由none重新赋值为SecureCookieSessionInterface类open_session方法的结果(SecureCookieSession对象)

- SecureCookieSession对象就是一个字典

self.session = self.app.open_session(self.request)

def open_session(self, request):

    return self.session_interface.open_session(self, request)

# 之后这里可以自定义自己类 可以继承SecureCookieSessionInterface类

session_interface = SecureCookieSessionInterface()

class SecureCookieSessionInterface(SessionInterface):

    def open_session(self, app, request):

        s = self.get_signing_serializer(app)

        if s is None:

            return None

        # 去cookie中获取session作为key 对应的值(包含了此用户的session数据)

        val = request.cookies.get(app.session_cookie_name)

        if not val:

            return self.session_class()

        max_age = total_seconds(app.permanent_session_lifetime)

        try:

            data = s.loads(val, max_age=max_age)

            return self.session_class(data)

        except BadSignature:

            return self.session_class()

3. 之后调用request

#此时你如果调用request 会执行如下代码

request = LocalProxy(partial(_lookup_req_object, 'request'))

    _lookup_req_object 获取RequestContext()中用户的请求数据

4. 执行视图函数

1	`response = self.full_dispatch_request()`

4.1 触发只执行一次的装饰器函数 @before_first_request　

self.try_trigger_before_first_request_functions()

4.2 # 触发Flask的信号需要pip3 install blinker

1	`request_started.send(self)`

4.3 执行特殊装饰器 @before_request

有返回值 返回用户

没有返回值 触发并执行视图函数

rv = self.preprocess_request()

if rv is None:

    rv = self.dispatch_request()

4.4 执行请求之后的装饰器 @after_request 且处理session

return self.finalize_request(rv)

    def finalize_request(self, rv, from_error_handler=False):

        response = self.process_response(response)

            def process_response(self, response):

                # 处理session

                if not self.session_interface.is_null_session(ctx.session):

                self.save_session(ctx.session, response)

上下文本质

Flask源码

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