flask 源码解析：路由

构建路由规则

flask

@app.route()

app.add_url_rule

add_url_rule(self,
rule, endpoint=None, view_func=None, **options)

rule

/path

/

endpoint

view_func

view_func

@app.route('/')
def hello():
return "hello, world!"

def hello():
return "hello, world!"

app.add_url_rule('/', 'hello', hello)

app.url_map

route

def route(self, rule, **options):
"""A decorator that is used to register a view function for a
given URL rule.  This does the same thing as :meth:`add_url_rule`
but is intended for decorator usage.
"""

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

return decorator

route

add_url_rule

def add_url_rule(self, rule, endpoint=None, view_func=None, **options):
"""Connects a URL rule.  Works exactly like the :meth:`route`
decorator.  If a view_func is provided it will be registered with the
endpoint.
"""

methods = options.pop('methods', None)

rule = self.url_rule_class(rule, methods=methods, **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

self.url_map

self.view_functions

url_map

werkzeug.routeing:Map

rule

werkzeug.routing:Rule

view_functions

Rule

Map

url

view_func

AssertionError

werkzeug 路由逻辑

werkzeug

werkzeug

>>> m = Map([
...     Rule('/', endpoint='index'),
...     Rule('/downloads/', endpoint='downloads/index'),
...     Rule('/downloads/<int:id>', endpoint='downloads/show')
... ])
>>> urls = m.bind("example.com", "/")
>>> urls.match("/", "GET")
('index', {})
>>> urls.match("/downloads/42")
('downloads/show', {'id': 42})

>>> urls.match("/downloads")
Traceback (most recent call last):
...
RequestRedirect: http://example.com/downloads/ >>> urls.match("/missing")
Traceback (most recent call last):
...
NotFound: 404 Not Found

werkzeug

m.add

m.bind

urls.match

endpoint

werkzeug

werkzeug

flask

flask 路由实现

dispatch_request

def dispatch_request(self):
"""Does the request dispatching.  Matches the URL and returns the
return value of the view or error handler.  This does not have to
be a response object.  In order to convert the return value to a
proper response object, call :func:`make_response`.
"""

req = _request_ctx_stack.top.request
if req.routing_exception is not None:
self.raise_routing_exception(req)
rule = req.url_rule

# dispatch to the handler for that endpoint
return self.view_functions[rule.endpoint](**req.view_args)

request

endpoint

view_functions

endpoint

view_func

view_functions

req.url_rule

_request_ctx_stack.top.request

flask

_request_ctx_stack

RequestContext

flask/ctx.py

class RequestContext(object):
def __init__(self, app, environ, request=None):
self.app = app
self.request = request
self.url_adapter = app.create_url_adapter(self.request)
self.match_request()

def match_request(self):
"""Can be overridden by a subclass to hook into the matching
of the request.
"""
try:
url_rule, self.request.view_args = \
self.url_adapter.match(return_rule=True)
self.request.url_rule = url_rule
except HTTPException as e:
self.request.routing_exception = e

class Flask(_PackageBoundObject):
def create_url_adapter(self, request):
"""Creates a URL adapter for the given request.  The URL adapter
is created at a point where the request context is not yet set up
so the request is passed explicitly.
"""
if request is not None:
return self.url_map.bind_to_environ(request.environ,
server_name=self.config['SERVER_NAME'])

app.create_url_adapter

app

url_map

bind_to_environ

bind

match_request

url_adapter.match

url_rule.endpoint

flask

@app.route

app.add_url_rule

dispatch_request

match 实现

flask

werkzeug

match

Map

Rule

match

rule.match

Rule.match

def match(self, path):
"""Check if the rule matches a given path. Path is a string in the
form ``"subdomain|/path(method)"`` and is assembled by the map.  If
the map is doing host matching the subdomain part will be the host
instead.

If the rule matches a dict with the converted values is returned,
otherwise the return value is `None`.
"""
if not self.build_only:
m = self._regex.search(path)
if m is not None:
groups = m.groupdict()

result = {}
for name, value in iteritems(groups):
try:
value = self._converters[name].to_python(value)
except ValidationError:
return
result[str(name)] = value
if self.defaults:
result.update(self.defaults)

return result