I have an ajax post request:

```
  function downloadElevationMap() {
    var jsonData = ko.toJSON(mod.SelectedItem);
    $.ajax({
        url: '/Home/GetData/',
        type: 'POST',
        contentType: "application/json; charset=utf-8",
        dataType: 'json',
        data: jsonData,
        success: function (data) {
            console.log("OK");
        },
    });
}

```

The controller method recive data correct. The code is presented below:

```
public FileStreamResult GetData(Mv jsonData)
        {
            var resultAll = jsonData.Data.Select(d => d.y).ToList();
            var str = new StringBuilder();
            _fileName = "ses"+jsonData.Path;
            foreach (var d in resultAll)
            {
                str.Append(d + " ");
            }
            var byteArray = Encoding.ASCII.GetBytes(str.ToString());
            var stream = new MemoryStream(byteArray);
            return File(stream, "text/plain", string.Format("{0}.txt", _fileName));
        }

```

Mv - is my class that represent data. When debug the both `str` and stream `variable` contain correct data. 

Function `downloadElevationMap()` is called by `onclick="downloadElevationMap()"`

I just want when `downloadElevationMap()` is called the `GetData` controller return a file for download. But simply nothing happend. Where the error is?