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Web application
import webapi as web
import webapi, wsgi, utils
import debugerror
import httpserver
from utils import lstrips, safeunicode
import sys
import urllib
import traceback
import itertools
import os
import types
from exceptions import SystemExit
import wsgiref.handlers
except ImportError:
pass # don't break people with old Pythons
__all__ = [
"application", "auto_application",
"subdir_application", "subdomain_application",
"loadhook", "unloadhook",
class application:
Application to delegate requests based on path.
>>> urls = ("/hello", "hello")
>>> app = application(urls, globals())
>>> class hello:
... def GET(self): return "hello"
>>> app.request("/hello").data
def __init__(self, mapping=(), fvars={}, autoreload=None):
if autoreload is None:
autoreload = web.config.get('debug', False)
self.fvars = fvars
self.processors = []
if autoreload:
def main_module_name():
mod = sys.modules['__main__']
file = getattr(mod, '__file__', None) # make sure this works even from python interpreter
return file and os.path.splitext(os.path.basename(file))[0]
def modname(fvars):
"""find name of the module name from fvars."""
file, name = fvars.get('__file__'), fvars.get('__name__')
if file is None or name is None:
return None
if name == '__main__':
# Since the __main__ module can't be reloaded, the module has
# to be imported using its file name.
name = main_module_name()
return name
mapping_name = utils.dictfind(fvars, mapping)
module_name = modname(fvars)
def reload_mapping():
"""loadhook to reload mapping and fvars."""
mod = __import__(module_name, None, None, [''])
mapping = getattr(mod, mapping_name, None)
if mapping:
self.fvars = mod.__dict__
if mapping_name and module_name:
# load __main__ module usings its filename, so that it can be reloaded.
if main_module_name() and '__main__' in sys.argv:
except ImportError:
def _load(self):
def _unload(self):
web.ctx.app_stack = web.ctx.app_stack[:-1]
if web.ctx.app_stack:
# this is a sub-application, revert ctx to earlier state.
oldctx = web.ctx.get('_oldctx')
if oldctx:
web.ctx.home = oldctx.home
web.ctx.homepath = oldctx.homepath
web.ctx.path = oldctx.path
web.ctx.fullpath = oldctx.fullpath
def _cleanup(self):
# Threads can be recycled by WSGI servers.
# Clearing up all thread-local state to avoid interefereing with subsequent requests.
def init_mapping(self, mapping):
self.mapping = list(, 2))
def add_mapping(self, pattern, classname):
self.mapping.append((pattern, classname))
def add_processor(self, processor):
Adds a processor to the application.
>>> urls = ("/(.*)", "echo")
>>> app = application(urls, globals())
>>> class echo:
... def GET(self, name): return name
>>> def hello(handler): return "hello, " + handler()
>>> app.add_processor(hello)
>>> app.request("/").data
def request(self, localpart='/', method='GET', data=None,
host="", headers=None, https=False, **kw):
"""Makes request to this application for the specified path and method.
Response will be a storage object with data, status and headers.
>>> urls = ("/hello", "hello")
>>> app = application(urls, globals())
>>> class hello:
... def GET(self):
... web.header('Content-Type', 'text/plain')
... return "hello"
>>> response = app.request("/hello")
>>> response.status
'200 OK'
>>> response.headers['Content-Type']
To use https, use https=True.
>>> urls = ("/redirect", "redirect")
>>> app = application(urls, globals())
>>> class redirect:
... def GET(self): raise web.seeother("/foo")
>>> response = app.request("/redirect")
>>> response.headers['Location']
>>> response = app.request("/redirect", https=True)
>>> response.headers['Location']
The headers argument specifies HTTP headers as a mapping object
such as a dict.
>>> urls = ('/ua', 'uaprinter')
>>> class uaprinter:
... def GET(self):
... return 'your user-agent is ' + web.ctx.env['HTTP_USER_AGENT']
>>> app = application(urls, globals())
>>> app.request('/ua', headers = {
... 'User-Agent': 'a small jumping bean/1.0 (compatible)'
... }).data
'your user-agent is a small jumping bean/1.0 (compatible)'
path, maybe_query = urllib.splitquery(localpart)
query = maybe_query or ""
if 'env' in kw:
env = kw['env']
env = {}
env = dict(env, HTTP_HOST=host, REQUEST_METHOD=method, PATH_INFO=path, QUERY_STRING=query, HTTPS=str(https))
headers = headers or {}
for k, v in headers.items():
env['HTTP_' + k.upper().replace('-', '_')] = v
if 'HTTP_CONTENT_TYPE' in env:
if method not in ["HEAD", "GET"]:
data = data or ''
import StringIO
if isinstance(data, dict):
q = urllib.urlencode(data)
q = data
env['wsgi.input'] = StringIO.StringIO(q)
if not env.get('CONTENT_TYPE', '').lower().startswith('multipart/') and 'CONTENT_LENGTH' not in env:
env['CONTENT_LENGTH'] = len(q)
response =
def start_response(status, headers):
response.status = status
response.headers = dict(headers)
response.header_items = headers = "".join(self.wsgifunc()(env, start_response))
return response
def browser(self):
import browser
return browser.AppBrowser(self)
def handle(self):
fn, args = self._match(self.mapping, web.ctx.path)
return self._delegate(fn, self.fvars, args)
def handle_with_processors(self):
def process(processors):
if processors:
p, processors = processors[0], processors[1:]
return p(lambda: process(processors))
return self.handle()
except web.HTTPError:
except (KeyboardInterrupt, SystemExit):
print >> web.debug, traceback.format_exc()
raise self.internalerror()
# processors must be applied in the resvere order. (??)
return process(self.processors)
def wsgifunc(self, *middleware):
"""Returns a WSGI-compatible function for this application."""
def peep(iterator):
"""Peeps into an iterator by doing an iteration
and returns an equivalent iterator.
# wsgi requires the headers first
# so we need to do an iteration
# and save the result for later
firstchunk =
except StopIteration:
firstchunk = ''
return itertools.chain([firstchunk], iterator)
def is_generator(x): return x and hasattr(x, 'next')
def wsgi(env, start_resp):
# clear threadlocal to avoid inteference of previous requests
# allow uppercase methods only
if web.ctx.method.upper() != web.ctx.method:
raise web.nomethod()
result = self.handle_with_processors()
if is_generator(result):
result = peep(result)
result = [result]
except web.HTTPError, e:
result = []
result = web.safestr(iter(result))
status, headers = web.ctx.status, web.ctx.headers
start_resp(status, headers)
def cleanup():
yield '' # force this function to be a generator
return itertools.chain(result, cleanup())
for m in middleware:
wsgi = m(wsgi)
return wsgi
def run(self, *middleware):
Starts handling requests. If called in a CGI or FastCGI context, it will follow
that protocol. If called from the command line, it will start an HTTP
server on the port named in the first command line argument, or, if there
is no argument, on port 8080.
`middleware` is a list of WSGI middleware which is applied to the resulting WSGI
return wsgi.runwsgi(self.wsgifunc(*middleware))
def stop(self):
"""Stops the http server started by run.
if httpserver.server:
httpserver.server = None
def cgirun(self, *middleware):
Return a CGI handler. This is mostly useful with Google App Engine.
There you can just do:
main = app.cgirun()
wsgiapp = self.wsgifunc(*middleware)
from google.appengine.ext.webapp.util import run_wsgi_app
return run_wsgi_app(wsgiapp)
except ImportError:
# we're not running from within Google App Engine
return wsgiref.handlers.CGIHandler().run(wsgiapp)
def gaerun(self, *middleware):
Starts the program in a way that will work with Google app engine,
no matter which version you are using (2.5 / 2.7)
If it is 2.5, just normally start it with app.gaerun()
If it is 2.7, make sure to change the app.yaml handler to point to the
global variable that contains the result of app.gaerun()
For example:
in app.yaml (where is where the main code is located)
- url: /.*
Make sure that the app variable is globally accessible
wsgiapp = self.wsgifunc(*middleware)
# check what version of python is running
version = sys.version_info[:2]
major = version[0]
minor = version[1]
if major != 2:
raise EnvironmentError("Google App Engine only supports python 2.5 and 2.7")
# if 2.7, return a function that can be run by gae
if minor == 7:
return wsgiapp
# if 2.5, use run_wsgi_app
elif minor == 5:
from google.appengine.ext.webapp.util import run_wsgi_app
return run_wsgi_app(wsgiapp)
raise EnvironmentError("Not a supported platform, use python 2.5 or 2.7")
except ImportError:
return wsgiref.handlers.CGIHandler().run(wsgiapp)
def load(self, env):
"""Initializes ctx using env."""
ctx = web.ctx
ctx.status = '200 OK'
ctx.headers = []
ctx.output = ''
ctx.environ = ctx.env = env = env.get('HTTP_HOST')
if env.get('wsgi.url_scheme') in ['http', 'https']:
ctx.protocol = env['wsgi.url_scheme']
elif env.get('HTTPS', '').lower() in ['on', 'true', '1']:
ctx.protocol = 'https'
ctx.protocol = 'http'
ctx.homedomain = ctx.protocol + '://' + env.get('HTTP_HOST', '[unknown]')
ctx.homepath = os.environ.get('REAL_SCRIPT_NAME', env.get('SCRIPT_NAME', ''))
ctx.home = ctx.homedomain + ctx.homepath
#@@ home is changed when the request is handled to a sub-application.
#@@ but the real home is required for doing absolute redirects.
ctx.realhome = ctx.home
ctx.ip = env.get('REMOTE_ADDR')
ctx.method = env.get('REQUEST_METHOD')
ctx.path = env.get('PATH_INFO')
# requires:
if env.get('SERVER_SOFTWARE', '').startswith('lighttpd/'):
ctx.path = lstrips(env.get('REQUEST_URI').split('?')[0], ctx.homepath)
# Apache and CherryPy webservers unquote the url but lighttpd doesn't.
# unquote explicitly for lighttpd to make ctx.path uniform across all servers.
ctx.path = urllib.unquote(ctx.path)
if env.get('QUERY_STRING'):
ctx.query = '?' + env.get('QUERY_STRING', '')
ctx.query = ''
ctx.fullpath = ctx.path + ctx.query
for k, v in ctx.iteritems():
# convert all string values to unicode values and replace
# malformed data with a suitable replacement marker.
if isinstance(v, str):
ctx[k] = v.decode('utf-8', 'replace')
# status must always be str
ctx.status = '200 OK'
ctx.app_stack = []
def _delegate(self, f, fvars, args=[]):
def handle_class(cls):
meth = web.ctx.method
if meth == 'HEAD' and not hasattr(cls, meth):
meth = 'GET'
if not hasattr(cls, meth):
raise web.nomethod(cls)
tocall = getattr(cls(), meth)
return tocall(*args)
def is_class(o): return isinstance(o, (types.ClassType, type))
if f is None:
raise web.notfound()
elif isinstance(f, application):
return f.handle_with_processors()
elif is_class(f):
return handle_class(f)
elif isinstance(f, basestring):
if f.startswith('redirect '):
url = f.split(' ', 1)[1]
if web.ctx.method == "GET":
x = web.ctx.env.get('QUERY_STRING', '')
if x:
url += '?' + x
raise web.redirect(url)
elif '.' in f:
mod, cls = f.rsplit('.', 1)
mod = __import__(mod, None, None, [''])
cls = getattr(mod, cls)
cls = fvars[f]
return handle_class(cls)
elif hasattr(f, '__call__'):
return f()
return web.notfound()
def _match(self, mapping, value):
for pat, what in mapping:
if isinstance(what, application):
if value.startswith(pat):
f = lambda: self._delegate_sub_application(pat, what)
return f, None
elif isinstance(what, basestring):
what, result = utils.re_subm('^' + pat + '$', what, value)
result = utils.re_compile('^' + pat + '$').match(value)
if result: # it's a match
return what, [x for x in result.groups()]
return None, None
def _delegate_sub_application(self, dir, app):
"""Deletes request to sub application `app` rooted at the directory `dir`.
The home, homepath, path and fullpath values in web.ctx are updated to mimic request
to the subapp and are restored after it is handled.
@@Any issues with when used with yield?
web.ctx._oldctx =
web.ctx.home += dir
web.ctx.homepath += dir
web.ctx.path = web.ctx.path[len(dir):]
web.ctx.fullpath = web.ctx.fullpath[len(dir):]
return app.handle_with_processors()
def get_parent_app(self):
if self in web.ctx.app_stack:
index = web.ctx.app_stack.index(self)
if index > 0:
return web.ctx.app_stack[index-1]
def notfound(self):
"""Returns HTTPError with '404 not found' message"""
parent = self.get_parent_app()
if parent:
return parent.notfound()
return web._NotFound()
def internalerror(self):
"""Returns HTTPError with '500 internal error' message"""
parent = self.get_parent_app()
if parent:
return parent.internalerror()
elif web.config.get('debug'):
import debugerror
return debugerror.debugerror()
return web._InternalError()
class auto_application(application):
"""Application similar to `application` but urls are constructed
automatiacally using metaclass.
>>> app = auto_application()
>>> class hello(
... def GET(self): return "hello, world"
>>> class foo(
... path = '/foo/.*'
... def GET(self): return "foo"
>>> app.request("/hello").data
'hello, world'
>>> app.request('/foo/bar').data
def __init__(self):
class metapage(type):
def __init__(klass, name, bases, attrs):
type.__init__(klass, name, bases, attrs)
path = attrs.get('path', '/' + name)
# path can be specified as None to ignore that class
# typically required to create a abstract base class.
if path is not None:
self.add_mapping(path, klass)
class page:
path = None
__metaclass__ = metapage = page
# The application class already has the required functionality of subdir_application
subdir_application = application
class subdomain_application(application):
Application to delegate requests based on the host.
>>> urls = ("/hello", "hello")
>>> app = application(urls, globals())
>>> class hello:
... def GET(self): return "hello"
>>> mapping = (r"hello\.example\.com", app)
>>> app2 = subdomain_application(mapping)
>>> app2.request("/hello", host="").data
>>> response = app2.request("/hello", host="")
>>> response.status
'404 Not Found'
'not found'
def handle(self):
host =':')[0] #strip port
fn, args = self._match(self.mapping, host)
return self._delegate(fn, self.fvars, args)
def _match(self, mapping, value):
for pat, what in mapping:
if isinstance(what, basestring):
what, result = utils.re_subm('^' + pat + '$', what, value)
result = utils.re_compile('^' + pat + '$').match(value)
if result: # it's a match
return what, [x for x in result.groups()]
return None, None
def loadhook(h):
Converts a load hook into an application processor.
>>> app = auto_application()
>>> def f(): "something done before handling request"
>>> app.add_processor(loadhook(f))
def processor(handler):
return handler()
return processor
def unloadhook(h):
Converts an unload hook into an application processor.
>>> app = auto_application()
>>> def f(): "something done after handling request"
>>> app.add_processor(unloadhook(f))
def processor(handler):
result = handler()
is_generator = result and hasattr(result, 'next')
# run the hook even when handler raises some exception
if is_generator:
return wrap(result)
return result
def wrap(result):
def next():
# call the hook at the and of iterator
result = iter(result)
while True:
yield next()
return processor
def autodelegate(prefix=''):
Returns a method that takes one argument and calls the method named prefix+arg,
calling `notfound()` if there isn't one. Example:
urls = ('/prefs/(.*)', 'prefs')
class prefs:
GET = autodelegate('GET_')
def GET_password(self): pass
def GET_privacy(self): pass
`GET_password` would get called for `/prefs/password` while `GET_privacy` for
`GET_privacy` gets called for `/prefs/privacy`.
If a user visits `/prefs/password/change` then `GET_password(self, '/change')`
is called.
def internal(self, arg):
if '/' in arg:
first, rest = arg.split('/', 1)
func = prefix + first
args = ['/' + rest]
func = prefix + arg
args = []
if hasattr(self, func):
return getattr(self, func)(*args)
except TypeError:
raise web.notfound()
raise web.notfound()
return internal
class Reloader:
"""Checks to see if any loaded modules have changed on disk and,
if so, reloads them.
"""File suffix of compiled modules."""
if sys.platform.startswith('java'):
SUFFIX = '$py.class'
SUFFIX = '.pyc'
def __init__(self):
self.mtimes = {}
def __call__(self):
for mod in sys.modules.values():
def check(self, mod):
# jython registers java packages as modules but they either
# don't have a __file__ attribute or its value is None
if not (mod and hasattr(mod, '__file__') and mod.__file__):
mtime = os.stat(mod.__file__).st_mtime
except (OSError, IOError):
if mod.__file__.endswith(self.__class__.SUFFIX) and os.path.exists(mod.__file__[:-1]):
mtime = max(os.stat(mod.__file__[:-1]).st_mtime, mtime)
if mod not in self.mtimes:
self.mtimes[mod] = mtime
elif self.mtimes[mod] < mtime:
self.mtimes[mod] = mtime
except ImportError:
if __name__ == "__main__":
import doctest
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