I'm a plete beginner here and facing a problem in passing javascript variable into flask. Please note that my question is pletely different from previous question that has been asked.

This is my code:

JavaScript

var dd = {'mvar': 1};

    $.ajax({
      type: "POST",
      contentType: "application/json; charset=utf-8",
      url: "/",
      data: JSON.stringify(dd),
      success: function (data) {
        alert("DONE!")
      },
      dataType: "json"
    });

Flask(edited)

@app.route('/', methods=['GET', 'POST'])
def new():

  form = InputForm(request.form)
  v = request.get_json().get('mvar')
  print(v)

  return render_template('new.html',form=form,v=v)

However, when the output that I get when print out the result is "None" while I expected it to be "1"

Really hope that experts can help me, thank you!

I'm a plete beginner here and facing a problem in passing javascript variable into flask. Please note that my question is pletely different from previous question that has been asked.

This is my code:

JavaScript

var dd = {'mvar': 1};

    $.ajax({
      type: "POST",
      contentType: "application/json; charset=utf-8",
      url: "/",
      data: JSON.stringify(dd),
      success: function (data) {
        alert("DONE!")
      },
      dataType: "json"
    });

Flask(edited)

@app.route('/', methods=['GET', 'POST'])
def new():

  form = InputForm(request.form)
  v = request.get_json().get('mvar')
  print(v)

  return render_template('new.html',form=form,v=v)

However, when the output that I get when print out the result is "None" while I expected it to be "1"

Really hope that experts can help me, thank you!

• javascript
• python
• ajax
• post
• flask

• You can using javascript set value of mvar to session and get value of session in flask – tuannv256 Commented Aug 3, 2017 at 2:01
• Can you teach me how to do it? I did not learn on session yet – iyzad Commented Aug 3, 2017 at 2:04
• I'm not good at JavaScript. Do you know how to set session variable like this. To get session variable in Flask, refer Flask session – tuannv256 Commented Aug 3, 2017 at 2:58
• I'm not sure how it gonna be – iyzad Commented Aug 3, 2017 at 3:00

2 Answers 2

The Request.get_json() method is what you are looking for in your Flask code.

data = request.get_json()

edit here is the exact pattern i use which works:

javascript:

$.ajax({
    type: "POST",
    url: "{{ url_for("get_post_json") }}",
    contentType: "application/json",
    data: JSON.stringify({hello: "world"}),
    dataType: "json",
    success: function(response) {
        console.log(response);
    },
    error: function(err) {
        console.log(err);
    }
});

python:

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

    return jsonify(status="success", data=data)

Instead of using

v = request.form.get('mvar', type=int)

Use this

v = request.get_json().get('mvar')

Once you print v then you should get it.