Send json parms in a post request in Flask API python getting errror ValueError("No JSON object could be decoded")

Question

I'm developing a Flask API. I want to create an API route that with accept JSON parameters and based on that json to do a search in database. My code looks like this:

@mod_api.route('/test', methods=['POST'])
def test():
    query_params = json.loads(request.data)
    json_resp = mongo.db.mydb.find(query_params)
    return Response(response=json_util.dumps(json_resp), status=200, mimetype='application/json')

Now when I run the api i go to my route: This example looks like this:

http://0.0.0.0:5002/api/test

I don't know exactly how to send a json parameter. If i do like this:

http://0.0.0.0:5002/api/test?{'var1':'123', 'var2':'456'}

I get an error ValueError("No JSON object could be decoded")

How to send this json parameter?

@furas thank you for your answer? Can you explain it more please? — Lindages
– Lindages, Commented Jan 7, 2016 at 12:52
first print request.data to see what you get. maybe you should use test?args="{'var1':'123', 'var2':'456'}" or test?var1=123&var2=456 to get correct values in request.data. — furas
– furas, Commented Jan 7, 2016 at 13:04

jumbopap · Accepted Answer · 2016-01-07 16:37:46Z

1

You likely aren't supplying JSON data. With your browser at http://0.0.0.0:5002, use XHR in the browser console to test out your API.

var xmlhttp = new XMLHttpRequest();   // new HttpRequest instance 
xmlhttp.open("POST", "/api/test");
xmlhttp.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
xmlhttp.send(JSON.stringify({'var1':'123', 'var2':'456'}));

You can see the request/response in the Network tab, and the Flask process will show the request happening as well.

answered Jan 7, 2016 at 16:37

jumbopap

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Comments

lord63. j · Accepted Answer · 2016-01-08 08:08:51Z

0

First, I want to point out that usually we use request.get_json() to get the json data, request.data contains the incoming request data that flask can't handle.

Test your app with curl should be easy, send the json data this way:

$ curl -H "Content-Type: application/json" -X POST -d '{"var1":"123", "var2":"456"}' http://localhost:5000/api/test

answered Jan 8, 2016 at 8:08

lord63. j

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