flask-源码请求源码

Posted 2020-10-20 forjie

请求开始

from flask import Flask
app=Flask(__name__)

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

1,请求进来时执行app__call__方法,调用def wsgi_app(self, environ, start_response)

environ封装了所有的请求信息.

def wsgi_app(self, environ, start_response):
    ctx = self.request_context(environ)
        ctx.push()
        error = None
        try:
            try:
                response = self.full_dispatch_request()
            except Exception as e:
                error = e
                response = self.handle_exception(e)
            except:
                error = sys.exc_info()[1]
                raise
            return response(environ, start_response)
        finally:
            if self.should_ignore_error(error):
                error = None
            ctx.auto_pop(error)

执行def wsgi_app(self, environ, start_response):

==>  ctx = self.request_context(environ)
　　

    def __init__(self, app, environ, request=None):
        self.app = app
        if request is None:
            request = app.request_class(environ)
        self.request = request
        self.url_adapter = app.create_url_adapter(self.request)
        self.flashes = None
        self.session = None
....
 if request is None:
            request = app.request_class(environ)
        self.request = request
当没有request进来时,执行request_class方法,把数据封装BaseRequest类中

调用RequestContext的实例化

==> ctx.push()

top = _request_ctx_stack.top      #从请求中拿出函数
        if top is not None and top.preserved:    #没有请求则返回
            top.pop(top._preserved_exc)
app_ctx = _app_ctx_stack.top
        if app_ctx is None or app_ctx.app != self.app:  #如果没有请求
            app_ctx = self.app.app_context()
            app_ctx.push()
            self._implicit_app_ctx_stack.append(app_ctx) #把函数命令放到列表里,等待后面for循环并执行
        else:
            self._implicit_app_ctx_stack.append(None)

        if hasattr(sys, ‘exc_clear‘):
            sys.exc_clear()

        _request_ctx_stack.push(self)
self.session = self.app.open_session(self.request)
        if self.session is None:
            self.session = self.app.make_null_session()

View Code

==> response = self.full_dispatch_request()
#开始走中间件,视图函数

def full_dispatch_request(self):
    self.try_trigger_before_first_request_functions()  #执行中间件
            try:
            #视图函数开始,发送信号
            
            request_started.send(self)    #发送信号,表示开始运行函数进入中间件.
            rv = self.preprocess_request()    #这里也是走中间件
            if rv is None:      #列表为空
                rv = self.dispatch_request()   #这里执行视图函数
        except Exception as e:
            rv = self.handle_user_exception(e)
        return self.finalize_request(rv)   视图函数执行完

response = self.full_dispatch_request()

==>  def finalize_request(self, rv, from_error_handler=False):
函数执行完成最后走这里

 response = self.make_response(rv)
        try:
            response = self.process_response(response)
            request_finished.send(self, response=response)     #最后发送信号
        except Exception:
            if not from_error_handler:
                raise
            self.logger.exception(‘Request finalizing failed with an ‘
                                  ‘error while handling an error‘)
        return response