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
