Problems in trying to POST json data to python flask server

Question

I am trying to Post a json to my flask server, but the post request always fails. This is how I am doing it, any idea what is am doing wrong?

jQuery.ajax({
    url:'/someLink',
    method:'POST',
    data:JSON.stringify({"sampleKey":"Value"}),
    success:function(data){
        console.log(data);
    },
});

And my flask server looks something like

@app.route('/someLink', methods=['POST'])
def someFn():
 sampleKey = str(request.form['sampleKey'])

I believe there is some data serializing issue, as the following request works

jQuery.post('/someLink',{"sampleKey":"Value"},function(data){console.log(data)});

Answer 1

jQuery's .ajax accepts either a plain object, or a query string as parameters for data. It does not accept JSON encoded strings.

It sends the data as 'application/x-www-form-urlencoded; charset=UTF-8' 'application/x-www-form-urlencoded; charset=UTF-8' by default, which means unless you explicitly override this like Ian suggested possible (and the server is expecting it) you should not pass a JSON encoded string.

You can resolve this easily by passing the object.

From the API

data

Type: PlainObject or String

Data to be sent to the server. It is converted to a query string, if not already a string. It's appended to the url for GET-requests. See processData option to prevent this automatic processing. Object must be Key/Value pairs. If value is an Array, jQuery serializes multiple values with same key based on the value of the traditional setting (described below).

Try

jQuery.ajax({
    url:'/someLink',
    method:'POST',
    data:{"sampleKey":"Value"},
    success:function(data){
        console.log(data);
    }
});