How to properly serialize in Django or process in JS?

Question

JavaScript

Good day.
I'm trying to serialize form.error.items() into a view and process this js:

if user_form.is_valid():
\\....
else:
    data = dict([(k, [e for e in v]) for k,v in user_form.errors.items()])
    return JsonResponse(data)

When I process on the client side, I get a problem, because json is not valid:
{"username": ["A user with that username already exists."]}
Because []

success : function(json) {
            if (json.redirect){
            window.location.href = json.redirect;
            }
            $('.form-control').val('');
            var error = jQuery.parseJSON(data);
            $("#error").html(error.username);
            },

Answer 1

This is perfectly valid JSON. It's just that djanga is designed in such a way that it returns a list of all error messages that occurred during field validation.
The easiest way to put up and write
$("#error").html(error.username[0]);