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Added HTTP override middleware to docs. This fixes #582

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1 parent b2cf9e7 commit 18413ed1bf08261acf6d40f8ba65a98ae586bb29 @mitsuhiko mitsuhiko committed Oct 7, 2012
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  1. +1 −0 docs/patterns/index.rst
  2. +43 −0 docs/patterns/methodoverrides.rst
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@@ -37,3 +37,4 @@ Snippet Archives <http://flask.pocoo.org/snippets/>`_.
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deferredcallbacks
+ methodoverrides
@@ -0,0 +1,43 @@
+Adding HTTP Method Overrides
+============================
+
+Some HTTP proxies do not support arbitrary HTTP methods or newer HTTP
+methods (such as PATCH). In that case it's possible to “proxy” HTTP
+methods through another HTTP method in total violation of the protocol.
+
+The way this works is by letting the client do an HTTP POST request and
+set the ``X-HTTP-Method-Override`` header and set the value to the
+intended HTTP method (such as ``PATCH``).
+
+This can easily be accomplished with an HTTP middleware::
+
+ class HTTPMethodOverrideMiddleware(object):
+ allowed_methods = frozenset([
+ 'GET',
+ 'HEAD',
+ 'POST',
+ 'DELETE',
+ 'PUT',
+ 'PATCH',
+ 'OPTIONS'
+ ])
+ bodyless_methods = frozenset(['GET', 'HEAD', 'OPTIONS', 'DELETE'])
+
+ def __init__(self, app):
+ self.app = app
+
+ def __call__(self, environ, start_response):
+ method = environ.get('HTTP_X_HTTP_METHOD_OVERRIDE', '').upper()
+ if method in self.allowed_methods:
+ method = method.encode('ascii', 'replace')
+ environ['REQUEST_METHOD'] = method
+ if method in self.bodyless_methods:
+ environ['CONTENT_LENGTH'] = '0'
+ return self.app(environ, start_response)
+
+To use this with Flask this is all that is necessary::
+
+ from flask import Flask
+
+ app = Flask(__name__)
+ app.wsgi_app = HTTPMethodOverrideMiddleware(app.wsgi_app)

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