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Diffstat (limited to 'google_appengine/google/appengine/ext/webapp/__init__.py')
| -rwxr-xr-x | google_appengine/google/appengine/ext/webapp/__init__.py | 580 |
1 files changed, 580 insertions, 0 deletions
diff --git a/google_appengine/google/appengine/ext/webapp/__init__.py b/google_appengine/google/appengine/ext/webapp/__init__.py new file mode 100755 index 0000000..446475a --- /dev/null +++ b/google_appengine/google/appengine/ext/webapp/__init__.py @@ -0,0 +1,580 @@ +#!/usr/bin/env python +# +# Copyright 2007 Google Inc. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +"""An extremely simple WSGI web application framework. + +This module exports three primary classes: Request, Response, and +RequestHandler. You implement a web application by subclassing RequestHandler. +As WSGI requests come in, they are passed to instances of your RequestHandlers. +The RequestHandler class provides access to the easy-to-use Request and +Response objects so you can interpret the request and write the response with +no knowledge of the esoteric WSGI semantics. Here is a simple example: + + from google.appengine.ext import webapp + import wsgiref.simple_server + + class MainPage(webapp.RequestHandler): + def get(self): + self.response.out.write( + '<html><body><form action="/hello" method="post">' + 'Name: <input name="name" type="text" size="20"> ' + '<input type="submit" value="Say Hello"></form></body></html>') + + class HelloPage(webapp.RequestHandler): + def post(self): + self.response.headers['Content-Type'] = 'text/plain' + self.response.out.write('Hello, %s' % self.request.get('name')) + + application = webapp.WSGIApplication([ + ('/', MainPage), + ('/hello', HelloPage) + ], debug=True) + + server = wsgiref.simple_server.make_server('', 8080, application) + print 'Serving on port 8080...' + server.serve_forever() + +The WSGIApplication class maps URI regular expressions to your RequestHandler +classes. It is a WSGI-compatible application object, so you can use it in +conjunction with wsgiref to make your web application into, e.g., a CGI +script or a simple HTTP server, as in the example above. + +The framework does not support streaming output. All output from a response +is stored in memory before it is written. +""" + + +import cgi +import StringIO +import logging +import re +import sys +import traceback +import urlparse +import webob +import wsgiref.headers +import wsgiref.util + +RE_FIND_GROUPS = re.compile('\(.*?\)') +_CHARSET_RE = re.compile(r';\s*charset=([^;\s]*)', re.I) + +class Error(Exception): + """Base of all exceptions in the webapp module.""" + pass + + +class NoUrlFoundError(Error): + """Thrown when RequestHandler.get_url() fails.""" + pass + + +class Request(webob.Request): + """Abstraction for an HTTP request. + + Properties: + uri: the complete URI requested by the user + scheme: 'http' or 'https' + host: the host, including the port + path: the path up to the ';' or '?' in the URL + parameters: the part of the URL between the ';' and the '?', if any + query: the part of the URL after the '?' + + You can access parsed query and POST values with the get() method; do not + parse the query string yourself. + """ + + request_body_tempfile_limit = 0 + + uri = property(lambda self: self.url) + query = property(lambda self: self.query_string) + + def __init__(self, environ): + """Constructs a Request object from a WSGI environment. + + If the charset isn't specified in the Content-Type header, defaults + to UTF-8. + + Args: + environ: A WSGI-compliant environment dictionary. + """ + match = _CHARSET_RE.search(environ.get('CONTENT_TYPE', '')) + if match: + charset = match.group(1).lower() + else: + charset = 'utf-8' + + webob.Request.__init__(self, environ, charset=charset, + unicode_errors= 'ignore', decode_param_names=True) + + def get(self, argument_name, default_value='', allow_multiple=False): + """Returns the query or POST argument with the given name. + + We parse the query string and POST payload lazily, so this will be a + slower operation on the first call. + + Args: + argument_name: the name of the query or POST argument + default_value: the value to return if the given argument is not present + allow_multiple: return a list of values with the given name (deprecated) + + Returns: + If allow_multiple is False (which it is by default), we return the first + value with the given name given in the request. If it is True, we always + return an list. + """ + param_value = self.get_all(argument_name) + if allow_multiple: + return param_value + else: + if len(param_value) > 0: + return param_value[0] + else: + return default_value + + def get_all(self, argument_name): + """Returns a list of query or POST arguments with the given name. + + We parse the query string and POST payload lazily, so this will be a + slower operation on the first call. + + Args: + argument_name: the name of the query or POST argument + + Returns: + A (possibly empty) list of values. + """ + if self.charset: + argument_name = argument_name.encode(self.charset) + + param_value = self.params.getall(argument_name) + + for i in xrange(len(param_value)): + if isinstance(param_value[i], cgi.FieldStorage): + param_value[i] = param_value[i].value + + return param_value + + def arguments(self): + """Returns a list of the arguments provided in the query and/or POST. + + The return value is a list of strings. + """ + return list(set(self.params.keys())) + + def get_range(self, name, min_value=None, max_value=None, default=0): + """Parses the given int argument, limiting it to the given range. + + Args: + name: the name of the argument + min_value: the minimum int value of the argument (if any) + max_value: the maximum int value of the argument (if any) + default: the default value of the argument if it is not given + + Returns: + An int within the given range for the argument + """ + try: + value = int(self.get(name, default)) + except ValueError: + value = default + if max_value != None: + value = min(value, max_value) + if min_value != None: + value = max(value, min_value) + return value + + +class Response(object): + """Abstraction for an HTTP response. + + Properties: + out: file pointer for the output stream + headers: wsgiref.headers.Headers instance representing the output headers + """ + def __init__(self): + """Constructs a response with the default settings.""" + self.out = StringIO.StringIO() + self.__wsgi_headers = [] + self.headers = wsgiref.headers.Headers(self.__wsgi_headers) + self.headers['Content-Type'] = 'text/html; charset=utf-8' + self.headers['Cache-Control'] = 'no-cache' + self.set_status(200) + + def set_status(self, code, message=None): + """Sets the HTTP status code of this response. + + Args: + message: the HTTP status string to use + + If no status string is given, we use the default from the HTTP/1.1 + specification. + """ + if not message: + message = Response.http_status_message(code) + self.__status = (code, message) + + def clear(self): + """Clears all data written to the output stream so that it is empty.""" + self.out.seek(0) + self.out.truncate(0) + + def wsgi_write(self, start_response): + """Writes this response using WSGI semantics with the given WSGI function. + + Args: + start_response: the WSGI-compatible start_response function + """ + body = self.out.getvalue() + if isinstance(body, unicode): + body = body.encode('utf-8') + elif self.headers.get('Content-Type', '').endswith('; charset=utf-8'): + try: + body.decode('utf-8') + except UnicodeError, e: + logging.warning('Response written is not UTF-8: %s', e) + + if (self.headers.get('Cache-Control') == 'no-cache' and + not self.headers.get('Expires')): + self.headers['Expires'] = 'Fri, 01 Jan 1990 00:00:00 GMT' + self.headers['Content-Length'] = str(len(body)) + write = start_response('%d %s' % self.__status, self.__wsgi_headers) + write(body) + self.out.close() + + def http_status_message(code): + """Returns the default HTTP status message for the given code. + + Args: + code: the HTTP code for which we want a message + """ + if not Response.__HTTP_STATUS_MESSAGES.has_key(code): + raise Error('Invalid HTTP status code: %d' % code) + return Response.__HTTP_STATUS_MESSAGES[code] + http_status_message = staticmethod(http_status_message) + + __HTTP_STATUS_MESSAGES = { + 100: 'Continue', + 101: 'Switching Protocols', + 200: 'OK', + 201: 'Created', + 202: 'Accepted', + 203: 'Non-Authoritative Information', + 204: 'No Content', + 205: 'Reset Content', + 206: 'Partial Content', + 300: 'Multiple Choices', + 301: 'Moved Permanently', + 302: 'Moved Temporarily', + 303: 'See Other', + 304: 'Not Modified', + 305: 'Use Proxy', + 306: 'Unused', + 307: 'Temporary Redirect', + 400: 'Bad Request', + 401: 'Unauthorized', + 402: 'Payment Required', + 403: 'Forbidden', + 404: 'Not Found', + 405: 'Method Not Allowed', + 406: 'Not Acceptable', + 407: 'Proxy Authentication Required', + 408: 'Request Time-out', + 409: 'Conflict', + 410: 'Gone', + 411: 'Length Required', + 412: 'Precondition Failed', + 413: 'Request Entity Too Large', + 414: 'Request-URI Too Large', + 415: 'Unsupported Media Type', + 416: 'Requested Range Not Satisfiable', + 417: 'Expectation Failed', + 500: 'Internal Server Error', + 501: 'Not Implemented', + 502: 'Bad Gateway', + 503: 'Service Unavailable', + 504: 'Gateway Time-out', + 505: 'HTTP Version not supported' + } + + +class RequestHandler(object): + """Our base HTTP request handler. Clients should subclass this class. + + Subclasses should override get(), post(), head(), options(), etc to handle + different HTTP methods. + """ + def initialize(self, request, response): + """Initializes this request handler with the given Request and Response.""" + self.request = request + self.response = response + + def get(self, *args): + """Handler method for GET requests.""" + self.error(405) + + def post(self, *args): + """Handler method for POST requests.""" + self.error(405) + + def head(self, *args): + """Handler method for HEAD requests.""" + self.error(405) + + def options(self, *args): + """Handler method for OPTIONS requests.""" + self.error(405) + + def put(self, *args): + """Handler method for PUT requests.""" + self.error(405) + + def delete(self, *args): + """Handler method for DELETE requests.""" + self.error(405) + + def trace(self, *args): + """Handler method for TRACE requests.""" + self.error(405) + + def error(self, code): + """Clears the response output stream and sets the given HTTP error code. + + Args: + code: the HTTP status error code (e.g., 501) + """ + self.response.set_status(code) + self.response.clear() + + def redirect(self, uri, permanent=False): + """Issues an HTTP redirect to the given relative URL. + + Args: + uri: a relative or absolute URI (e.g., '../flowers.html') + permanent: if true, we use a 301 redirect instead of a 302 redirect + """ + if permanent: + self.response.set_status(301) + else: + self.response.set_status(302) + absolute_url = urlparse.urljoin(self.request.uri, uri) + self.response.headers['Location'] = str(absolute_url) + self.response.clear() + + def handle_exception(self, exception, debug_mode): + """Called if this handler throws an exception during execution. + + The default behavior is to call self.error(500) and print a stack trace + if debug_mode is True. + + Args: + exception: the exception that was thrown + debug_mode: True if the web application is running in debug mode + """ + self.error(500) + logging.exception(exception) + if debug_mode: + lines = ''.join(traceback.format_exception(*sys.exc_info())) + self.response.clear() + self.response.out.write('<pre>%s</pre>' % (cgi.escape(lines, quote=True))) + + @classmethod + def get_url(cls, *args, **kargs): + """Returns the url for the given handler. + + The default implementation uses the patterns passed to the active + WSGIApplication and the django urlresolvers module to create a url. + However, it is different from urlresolvers.reverse() in the following ways: + - It does not try to resolve handlers via module loading + - It does not support named arguments + - It performs some post-prosessing on the url to remove some regex + operators that urlresolvers.reverse_helper() seems to miss. + - It will try to fill in the left-most missing arguments with the args + used in the active request. + + Args: + args: Parameters for the url pattern's groups. + kwargs: Optionally contains 'implicit_args' that can either be a boolean + or a tuple. When it is True, it will use the arguments to the + active request as implicit arguments. When it is False (default), + it will not use any implicit arguments. When it is a tuple, it + will use the tuple as the implicit arguments. + the left-most args if some are missing from args. + + Returns: + The url for this handler/args combination. + + Raises: + NoUrlFoundError: No url pattern for this handler has the same + number of args that were passed in. + """ + + app = WSGIApplication.active_instance + pattern_map = app._pattern_map + + implicit_args = kargs.get('implicit_args', ()) + if implicit_args == True: + implicit_args = app.current_request_args + + min_params = len(args) + + urlresolvers = None + + for pattern_tuple in pattern_map.get(cls, ()): + num_params_in_pattern = pattern_tuple[1] + if num_params_in_pattern < min_params: + continue + + if urlresolvers is None: + from django.core import urlresolvers + + try: + num_implicit_args = max(0, num_params_in_pattern - len(args)) + merged_args = implicit_args[:num_implicit_args] + args + url = urlresolvers.reverse_helper(pattern_tuple[0], *merged_args) + url = url.replace('\\', '') + url = url.replace('?', '') + return url + except urlresolvers.NoReverseMatch: + continue + + logging.warning('get_url failed for Handler name: %r, Args: %r', + cls.__name__, args) + raise NoUrlFoundError + + +class WSGIApplication(object): + """Wraps a set of webapp RequestHandlers in a WSGI-compatible application. + + To use this class, pass a list of (URI regular expression, RequestHandler) + pairs to the constructor, and pass the class instance to a WSGI handler. + See the example in the module comments for details. + + The URL mapping is first-match based on the list ordering. + """ + + REQUEST_CLASS = Request + RESPONSE_CLASS = Response + + def __init__(self, url_mapping, debug=False): + """Initializes this application with the given URL mapping. + + Args: + url_mapping: list of (URI, RequestHandler) pairs (e.g., [('/', ReqHan)]) + debug: if true, we send Python stack traces to the browser on errors + """ + self._init_url_mappings(url_mapping) + self.__debug = debug + WSGIApplication.active_instance = self + self.current_request_args = () + + def __call__(self, environ, start_response): + """Called by WSGI when a request comes in.""" + request = self.REQUEST_CLASS(environ) + response = self.RESPONSE_CLASS() + + WSGIApplication.active_instance = self + + handler = None + groups = () + for regexp, handler_class in self._url_mapping: + match = regexp.match(request.path) + if match: + handler = handler_class() + handler.initialize(request, response) + groups = match.groups() + break + + self.current_request_args = groups + + if handler: + try: + method = environ['REQUEST_METHOD'] + if method == 'GET': + handler.get(*groups) + elif method == 'POST': + handler.post(*groups) + elif method == 'HEAD': + handler.head(*groups) + elif method == 'OPTIONS': + handler.options(*groups) + elif method == 'PUT': + handler.put(*groups) + elif method == 'DELETE': + handler.delete(*groups) + elif method == 'TRACE': + handler.trace(*groups) + else: + handler.error(501) + except Exception, e: + handler.handle_exception(e, self.__debug) + else: + response.set_status(404) + + response.wsgi_write(start_response) + return [''] + + def _init_url_mappings(self, handler_tuples): + """Initializes the maps needed for mapping urls to handlers and handlers + to urls. + + Args: + handler_tuples: list of (URI, RequestHandler) pairs. + """ + + handler_map = {} + pattern_map = {} + url_mapping = [] + + for regexp, handler in handler_tuples: + + handler_map[handler.__name__] = handler + + if not regexp.startswith('^'): + regexp = '^' + regexp + if not regexp.endswith('$'): + regexp += '$' + + compiled = re.compile(regexp) + url_mapping.append((compiled, handler)) + + num_groups = len(RE_FIND_GROUPS.findall(regexp)) + handler_patterns = pattern_map.setdefault(handler, []) + handler_patterns.append((compiled, num_groups)) + + self._handler_map = handler_map + self._pattern_map = pattern_map + self._url_mapping = url_mapping + + def get_registered_handler_by_name(self, handler_name): + """Returns the handler given the handler's name. + + This uses the application's url mapping. + + Args: + handler_name: The __name__ of a handler to return. + + Returns: + The handler with the given name. + + Raises: + KeyError: If the handler name is not found in the parent application. + """ + try: + return self._handler_map[handler_name] + except: + logging.error('Handler does not map to any urls: %s', handler_name) + raise |