Flask request.get_json() raise BadRequest

Question

I have a Flask API with this endpoint :

@app.route('/classify/', methods=['POST'])
def classify():
    data = request.get_json()

When I POST a request with python, eveything is fine.

But when I use Postman, I get :

<class 'werkzeug.exceptions.BadRequest'> : 400: Bad Request

I send the same Json with both (I copy/paste it to be sure). I am fairly confident the issue is caused by some "\t" in my json, which are escaped by python but not by Postman.

Is there a way to retrieve the raw json, and process it (escape what needs to be escaped) in the app ? Or another way to get the json ?

EDIT : This is a different question from the one you suggested as duplicate, because yours suggest to use get_json, which is the problem in my case.

check out this answer: https://stackoverflow.com/questions/27369306/flask-jsonify-how-to-escape-characters — smundlay, Sep 07 '17 at 09:52
could you elaborate ? My issue is that get_json() is the only way to retrieve the json data, and it raises an error — CoMartel, Sep 07 '17 at 10:04

score 12 · Accepted Answer · answered Sep 07 '17 at 10:30

Ok, so it turns out you can replace :

data = request.get_json()

By :

data = json.loads(request.data, strict=False) # strict = False allow for escaped char

requests.data contains the json in string format, so you can process the characters that needs to be escaped.

score 3 · Answer 2 · answered Aug 11 '20 at 09:35

3

use request.data instead of request.get_json() if your data could be empty or a bad request will be raised!

answered Aug 11 '20 at 09:35

d0zingcat

929
8
10

score 1 · Answer 3 · answered Apr 05 '23 at 10:09

If you are getting 400 Bad Request or failed to decode json object: expecting value: line 1 column 1 (char 0), it might be because you are not sending it in json.

First verify that you are getting the request using return request.data. Check in postman that the Content-disposition is in json. Alternatively, use print(request.is_json).

When using request.get_json with Postman, make sure that you are sending the JSON as the raw request. See this image, make sure to select raw and JSON from the dropdown in the body

score -1 · Answer 4 · edited Dec 04 '20 at 08:31

All error about ajax and flask send data from templates for python file.

Recive all data of ajax json.

    data = request.get_json("")
    print(data)
    return "success!"
        
    Send data in ajax json.
    
    $(document).on('click','#texthide',function(){
            
        
            var text = $("#textVal").val();
            var font = $("#font_text").val();
            var color = $("#color_text").val();
            var start_text = $("#start_text").val();
            var end_text = $("#end_text").val();
            var vid_id = new_d
            console.log(text);
        
            $.ajax({
                url: '/videos/test_text',
                type: 'POST',
                contentType: 'application/json; charset=utf-8',
                datatype: "json",
              
                data: JSON.stringify(
                    
                {  text: $("#textVal").val(),
                    font: $("#font_text").val(),
                    color:  $("#color_text").val(),
                    start_text: $("#start_text").val(),
                    end_text: $("#end_text").val(),
                    video_id: new_d
                })
            });
        });

Flask request.get_json() raise BadRequest

4 Answers4

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