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. Then the method is replaced with the header value before being passed to Flask.
This can be accomplished with an HTTP middleware:
python
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:
environ['REQUEST_METHOD'] = method
if method in self.bodyless_methods:
environ['CONTENT_LENGTH'] = '0'
return self.app(environ, start_response)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:
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, wrap the app object with the middleware:
python
from flask import Flask
app = Flask(__name__)
app.wsgi_app = HTTPMethodOverrideMiddleware(app.wsgi_app)from flask import Flask
app = Flask(__name__)
app.wsgi_app = HTTPMethodOverrideMiddleware(app.wsgi_app)