cors preflight response

gistfile1.py

def cors_tween_factory(handler, registry):
    def handle_cors(request):
        if request.method == "OPTIONS":
            allowed_hosts = ['http://127.0.0.1:8000']
            cors_headers = [
                ('Access-Control-Allow-Credentials', "true"),
                ('Access-Control-Allow-Origin', request.headers['origin']),
                ('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS'),
                ('Access-Control-Allow-Headers', 
                    """X-CSRF-Token, X-Requested-With, Accept, """ +
                    """Accept-Version, Content-Length, Content-MD5, """ +
                    """Content-Type, Date, X-Api-Version"""),
                ('Access-Control-Max-Age', '60')]
            if request.headers['origin'] in allowed_hosts:
                for header in cors_headers:
                    request.response.headers[header[0]] = header[1]
            # Respond to options request
            return request.response
        else:
            # Respond to other requests
            return handler(request)
    # Return the tween to be called
    return handle_cors