Solve Cross Origin Resource Sharing with Flask

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For the following ajax post request for Flask (how can I use data posted from ajax in flask?):

$.ajax({
    url: "http://127.0.0.1:5000/foo", 
    type: "POST",
    contentType: "application/json",
    data: JSON.stringify({"inputVar": 1}),
    success: function( data ) { 
        alert( "success" + data );
    }   
});

I get a Cross Origin Resource Sharing (CORS) error:

No "Access-Control-Allow-Origin" header is present on the requested resource. 
Origin "null" is therefore not allowed access. 
The response had HTTP status code 500.

I tried solving it in the two following ways, but none seems to work.

1. Using Flask-CORS

This is a Flask extension for handling CORS that should make cross-origin AJAX possible.

• http://flask-cors.readthedocs.org/en/latest/
• How to enable CORS in flask and heroku
• Flask-cors wrapper not working when jwt auth wrapper is applied.
• Javascript - No 'Access-Control-Allow-Origin' header is present on the requested resource

My pythonServer.py using this solution:

from flask import Flask
from flask.ext.cors import CORS, cross_origin

app = Flask(__name__)
cors = CORS(app, resources={r"/foo": {"origins": "*"}})
app.config["CORS_HEADERS"] = "Content-Type"

@app.route("/foo", methods=["POST","OPTIONS"])
@cross_origin(origin="*",headers=["Content-Type","Authorization"])
def foo():
    return request.json["inputVar"]

if __name__ == "__main__":
    app.run()

2. Using specific Flask Decorator

This is an official Flask code snippet defining a decorator that should allow CORS on the functions it decorates.

• http://flask.pocoo.org/snippets/56/
• Python Flask cross site HTTP POST - doesn't work for specific allowed origins
• http://chopapp.com/#351l7gc3

My pythonServer.py using this solution:

from flask import Flask, make_response, request, current_app
from datetime import timedelta
from functools import update_wrapper

app = Flask(__name__)

def crossdomain(origin=None, methods=None, headers=None,
                max_age=21600, attach_to_all=True,
                automatic_options=True):
    if methods is not None:
        methods = ", ".join(sorted(x.upper() for x in methods))
    if headers is not None and not isinstance(headers, basestring):
        headers = ", ".join(x.upper() for x in headers)
    if not isinstance(origin, basestring):
        origin = ", ".join(origin)
    if isinstance(max_age, timedelta):
        max_age = max_age.total_seconds()

    def get_methods():
        if methods is not None:
            return methods

        options_resp = current_app.make_default_options_response()
        return options_resp.headers["allow"]

    def decorator(f):
        def wrapped_function(*args, **kwargs):
            if automatic_options and request.method == "OPTIONS":
                resp = current_app.make_default_options_response()
            else:
                resp = make_response(f(*args, **kwargs))
            if not attach_to_all and request.method != "OPTIONS":
                return resp

            h = resp.headers

            h["Access-Control-Allow-Origin"] = origin
            h["Access-Control-Allow-Methods"] = get_methods()
            h["Access-Control-Max-Age"] = str(max_age)
            if headers is not None:
                h["Access-Control-Allow-Headers"] = headers
            return resp

        f.provide_automatic_options = False
        return update_wrapper(wrapped_function, f)
    return decorator

@app.route("/foo", methods=["GET","POST","OPTIONS"])
@crossdomain(origin="*")
def foo():
    return request.json["inputVar"]

if __name__ == "__main__":
    app.run()

Can you please give some some indication of why that is?

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Solve Cross Origin Resource Sharing with Flask __del__: Questions

import time
time.sleep(5)   # Delays for 5 seconds. You can also use a float value.

import time
while True:
    print("This prints once a minute.")
    time.sleep(60) # Delay for 1 minute (60 seconds).

from time import sleep
sleep(0.1) # Time in seconds

Solve Cross Origin Resource Sharing with Flask __del__: Questions

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