转载 Flask中客户端 - 服务器 - web应用程序 是如何处理request生成response的?

class Flask:
def __call__(self, environ, start_response):
return self.wsgi_app(environ, start_response) def wsgi_app(self, environ, start_response):
ctx = self.request_context(environ)
error = None
try:
try:
ctx.push()
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)

def full_dispatch_request(self):
self.try_trigger_before_first_request_functions()
try:
request_started.send(self)
rv = self.preprocess_request()
if rv is None:
rv = self.dispatch_request()
except Exception as e:
rv = self.handle_user_exception(e)
return self.finalize_request(rv) def dispatch_request(self):
req = _request_ctx_stack.top.request
if req.routing_exception is not None:
self.raise_routing_exception(req)
rule = req.url_rule if getattr(rule, 'provide_automatic_options', False) \
and req.method == 'OPTIONS':
return self.make_default_options_response()
return self.view_functions[rule.endpoint](**req.view_args) self.view_functions = {}

def add_url_rule(self, rule, endpoint=None, view_func=None,provide_automatic_options=None, **options):
if endpoint is None:
endpoint = _endpoint_from_view_func(view_func)
options['endpoint'] = endpoint
methods = options.pop('methods', None) # if the methods are not given and the view_func object knows its
# methods we can use that instead. If neither exists, we go with
# a tuple of only ``GET`` as default.
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', ())) # starting with Flask 0.8 the view_func object can disable and
# force-enable the automatic options handling.
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

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

def finalize_request(self, rv, from_error_handler=False):
response = self.make_response(rv)
try:
response = self.process_response(response)
request_finished.send(self, response=response)
except Exception:
if not from_error_handler:
raise
self.logger.exception('Request finalizing failed with an ''error while handling an error')
return response