Question

Basically I get a value from a dropdownlist and pass it to a client method through AJAX. Based on this value, I get data, which I want to put into a textbox.

<script type="text/javascript">        
    $('#dropdownlist').change(function () {
        $.post('/Index/GetJSON/' + this.value, null,                               
            function (data) {
                $('#somefield').val(data)                                  
            });
    });
 </script>

So this method gets called:

[HttpPost]
public JsonResult GetJSON(int ID)
{
    return Json(data);
}

Markup

@Html.EditorFor(m => m.somefield)

somefield does change it’s value visually. But it does not get updated when I inspect it’s value. It’s as if val(data.ID) doesn’t register to the model. Due to my code, I can’t call ModelState.Clear() either…

The reason I use this approach, and not Ajax.Form and partial views, is because I have all the markup inside a HTML.BeginForm (which is submitted) with many different dropdownlists interacting through textboxes through AJAX, and you cannot nest Ajax.Form with HTML.BeginForm. Thus I cannot submit changes to the model through the Ajax.Form and call ModelState.Clear().

Answer 1

.val() sets the value property of an element if you want the change to be reflected in the elements value attr use .attr()

$('#somefield').attr('value', data)