Nonetype from getting data from an ajax POST with flask

Question

I'm having an issue trying to get data from an ajax query in my flask project. The server receives a "NoneType".

Here is my ajax query:

function doChart(val){
    console.log(val);
    $.ajax({    
            url : baseURL + '/get-stat-data',
            dataType: 'json',
        data: JSON.stringify({
              item: val
            }),
            type : "POST",
        success:function(data){
            //alert(data.substr(1, data.length - 2));
            alert(data);      
        },

        error: function(XMLHttpRequest, textStatus, errorThrown) { 
            alert("Status: " + textStatus+", Error: " + errorThrown);  
        } 
    });

}

Flask code :

@application.route("/get-stat-data",methods=['GET', 'POST'])
def get_stat_data():
    if request.method == "POST":
        json = request.json
        #con = connect_db()
        print("data = "+json)

Error I get :

print("data = "+json)
TypeError: Can't convert 'NoneType' object to str implicitly

Thank you for your help

You're sending stringified json and you're accepting json. Also, shouldn't it be `request.get_json()` — Gaurav Ojha, Apr 25 '17 at 08:07
I tried to change it with `request.get_json()`, got a `ValueError: View function did not return a response` — matcha-tea, Apr 25 '17 at 08:15
Your function needs to return something at the end. That's another issue. Add a return statement at the end and see if your print statement prints something. — Gaurav Ojha, Apr 25 '17 at 08:20
So I added a return statement. It passes in the if condition, but my data is still None. — matcha-tea, Apr 25 '17 at 08:26
Now instead of sending stringified data, send it without stringifying. See if that helps. — Gaurav Ojha, Apr 25 '17 at 08:31
Still getting this None value. I tried to parse it with `json.loads` but doesn't work — matcha-tea, Apr 25 '17 at 08:41

Gaurav Ojha · Accepted Answer · 2017-04-25T09:39:03.200

0

Put your data as

data: JSON.stringify({
       item: val
      }),

and mention a contentType: 'application/json;charset=UTF-8'

and then in Python -

postdata = request.json["item"]

This should do the trick.

edited Apr 25 '17 at 09:39

answered Apr 25 '17 at 08:46

Gaurav Ojha

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This solution get me a 400 bad Request with my POST – matcha-tea Apr 25 '17 at 09:05
Edited to an alternate approach. – Gaurav Ojha Apr 25 '17 at 09:39
It works, I just kept the `JSON.stringify` after that. Thank you! – matcha-tea Apr 25 '17 at 16:01

Nonetype from getting data from an ajax POST with flask

1 Answers1