how to get_argument from nested dictionary and array in tornado

Question

JavaScript client sending request like this:

$.ajax({
    url: 'http://localhost:7973/test',
    type: 'GET',
    data: {'host': 'mike', 'guests': {'name': ['car', 'ball'], 'age': [6, 10, 7]}},
    success: function(result){alert(result)},
    error: function(error){alert(error)}
});

Python server handling request using tornado:

import tornado.ioloop
import tornado.web


class TestHandler(tornado.web.RequestHandler):
    def get(self):
        host = self.get_argument('host')
        print(host)
        guests = self.get_argument('guests')
        print(guests)


def make_app():
    return tornado.web.Application([
        (r'/test', TestHandler)
    ])


if __name__ == "__main__":
    app = make_app()
    port = 7973
    app.listen(port)
    print('-' * 100)
    print('server started, listening to ', port, '...\n')
    tornado.ioloop.IOLoop.current().start()

The outputs on the server side is as below. Apparently, the 'host' argument is successfully got, but I have no clue how to get a argument whose value is a complex object itself (say an array or a dictionary). Please explain to me the mechanism of these casts and dumps between data structures and their string representation? I read the tornado document, but I'm not able to find the answer.

mike

WARNING:tornado.general:400 GET /test?host=mike&guests%5Bname%5D%5B%5D=car&guests%5Bname%5D%5B%5D=ball&guests%5Bage%5D%5B%5D=6&guests%5Bage%5D%5B%5D=10&guests%5Bage%5D%5B%5D=7 (::1): Missing argument guests

WARNING:tornado.access:400 GET /test?host=mike&guests%5Bname%5D%5B%5D=car&guests%5Bname%5D%5B%5D=ball&guests%5Bage%5D%5B%5D=6&guests%5Bage%5D%5B%5D=10&guests%5Bage%5D%5B%5D=7 (::1) 1.99ms

Answer 1

You can convert your json object to a json string.

change

data: {'host': 'mike', 'guests': {'name': ['car', 'ball'], 'age': [6, 10, 7]}}, 

to

data: JASON.stringify({'host': 'mike', 
                       'guests': {'name': ['car', 'ball'], 
                                  'age': [6, 10, 7]}}),

and then on the server side you can do:

guests_string = self.get_argument('guests')
guests = json.loads(guests_string)

guests should be a dictionary that you can do whatever with in Python.