When requesting for Restful APIs of backend, somtimes OPTION request is sent prior to a POST request to inquire http method support abilities of the backend server. When if the server returns only GET and POST methods while you need to send a PUT/DELETE … request?

To solve this problem, commonly two methods can be used under different circumstances.

Method 1 is used to use a _method field in data to override a POST request. See a JQuery POST request as an example below.

$.ajax({
    url:"http://localhost:8888/answer/"+answerId,
    type:"POST",
    data:{_method:"DELETE", id:issueId,userId:userId},
    dataType:"json",
    success:function(result){
        }                
   },
 });

Method 2 is to use X-HTTP-Method-Override header. Consider that if you’re writing a RIA client(Flex or silverlight), there would be no way to add _method field. So you have to use X-HTTP-Method-Override header. See a Flask example below. Or check Flask offical document here.

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)



from flask import Flask

app = Flask(__name__)
app.wsgi_app = HTTPMethodOverrideMiddleware(app.wsgi_app)