Send JSON-Request to Flask via Curl [duplicate]

Question

I setup a very simple post route in flask like this:

from flask import Flask, request

app = Flask(__name__)

@app.route('/post', methods=['POST'])
def post_route():
    if request.method == 'POST':

        data = request.get_json()

        print('Data Received: "{data}"'.format(data=data))
        return "Request Processed.\n"

app.run()

This is the curl request I am trying to send from the command-line:

curl localhost:5000/post -d '{"foo": "bar"}'

But still, it prints out 'Data Received: "None"'. So, it doesn't recognize the JSON I passed it.

Is it necessary to specify the json format in this case?

randomir · Accepted Answer · 2017-10-31 17:59:21Z

31

According to the get_json docs:

[..] function will return None if the mimetype is not application/json but this can be overridden by the force parameter.

So, either specify the mimetype of the incoming request to be application/json:

curl localhost:5000/post -d '{"foo": "bar"}' -H 'Content-Type: application/json'

or force JSON decoding with force=True:

data = request.get_json(force=True)

If running this on Windows (cmd.exe, not PowerShell), you'll also need to change the quoting of your JSON data, from single quotes to double quotes:

curl localhost:5000/post -d "{\"foo\": \"bar\"}" -H 'Content-Type: application/json'

edited Oct 31, 2017 at 17:59

answered Oct 31, 2017 at 11:16

randomir

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13 Comments

OhMad Over a year ago

Still not working, unfortunately.

randomir Over a year ago

Have you seen the edit of question? I thought you had a typo, but maybe that was also an error in your code. Check your print line uses format: print('Data Received: "{data}"'.format(data=data)).

randomir Over a year ago

What version of flask/curl do you use? On what platform?

OhMad Over a year ago

I fixed it. I guess it's a Windows specific problem with the double quotes. curl localhost:5000/post -d "{\"foo\": \"bar\"}" -H "Content-Type: application/json" works just fine.

randomir Over a year ago

@user305883, request.form contains form values. When you use JSON body encoding, that's not form. See an intro to forms here.

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