How to pass a nested dictionary to Flask's GET request handler

Question

I am trying to pass a nested dictionary as a parameter to a GET request, which is handled by a Flask worker. The whole setup is Nginx+Gunicorn+Flask. On the client, I am doing the following:

import requests

    def find_cabin():
        party = {'People' : [{'Age': 44, 'Gender': 'F', 'Habits': 'Smoking,Drinking'}, {'Age': 9, 'Gender': 'F'}
                    , {'Age': 4, 'Gender': 'F'}, {'Age': 49, 'Gender': 'M'}],
                 'Vehicles': [{'Make/Model': 'Honda Civic'}, {'Make/Model': 'Toyota RAV4'}],
                 'Must Haves':['Deck', 'Fireplace', 'Boat launch', {'Bedrooms': 2}]}
        uri = 'mysite.com/find_cabin'
        headers = {'Content-Type': 'application/json', 'Accept': 'text/plain'}
        res = requests.get(uri, data=json.dumps(party), headers=headers)
        return res.text

On the server, in my Flask handler, I am doing this:

@app.route('/find_cabin/', methods=['GET'])
def find_cabin():
    payload = request.data
    # payload is empty
    print ('payload for find_cabin: ', payload)
    #process request

The payload is empty. What am I missing? How should I pass complex nested structures to my Flask app?

Answer 1

The GET method does not have a body. Either encode your data as query parameters, or use a POST request. If you use POST, you can pass the data directly as JSON:

requests.post(url, json=party)

# within the view
party = request.get_json()

---

If you want to use GET you could just encode the JSON as query parameter.

requests.get(url, params={'party': json.dumps(party)})
# within the view
party = json.loads(request.args['party'])

You could also try to come up with some scheme to flatten a nested structure into query params, but this is not straightforward. Simple nesting could use '.' to separate paths, and lists could specify the key multiple times, but what if there is a nested list of nested objects?

This is not really a good use of query parameters, it would make more sense in this case to send a POST body.