i cant populate select in jquery,my code is in razor c#, i try this - ajax

Question

the content of the table is this
enter image description here
#section scripts{
<script>
function adddata() {
$.ajax({
type: "POST",
url: '?handler=GetItems',
headers: { "RequestVerificationToken": $('input[name="__RequestVerificationToken"]').val() },
data: { Id: $("#IdSelectIdPuesto").val() },
success: function (data) {
for (var i = 0; i < data.length; i++) {
$("#IdSelectlocalidad").append("<option value='" + data[i].value +
"' selected>" + data[i].text + "</option>");
}
},
error: function (result) {
alert("fail");
}
})
}
</script>
}
public JsonResult OnPostGetItems(int Id)
{
//displaydata1 = rTDBContext.Turnos.ToList();
var displayda = (from c in displaydata1
select c.LocNombre).Distinct().ToList();
return new JsonResult(new List<SelectListItem> = { new SelectListItem { Value = "1", Text = "LOcalidad" + 1 }, new SelectListItem { Value = "2", Text = "LOcalidad" + 2 } });
}
i'm trying a select distinct and add to the specified select the id and the locNombre to the text

Answer 1

If you want to change the options of $("#IdSelectlocalidad") with the id passed from ajax,here is a demo:
public JsonResult OnPostGetItems(int Id)
{
//displaydata1 = rTDBContext.Turnos.ToList();
var displayda = (from c in l
where c.Id==Id select new SelectListItem { Text=c.LocNombre, Value=c.Id+""}).Distinct().ToList();
return new JsonResult(displayda);
}
js(remove selected in the option,with the code it will select the first option by default):
#section scripts{
<script>
function adddata() {
$.ajax({
type: "POST",
url: '?handler=GetItems',
headers: { "RequestVerificationToken": $('input[name="__RequestVerificationToken"]').val() },
data: { Id: $("#IdSelectIdPuesto").val() },
success: function (data) {
for (var i = 0; i < data.length; i++) {
$("#IdSelectlocalidad").append("<option value='" + data[i].value +
"' >" + data[i].text + "</option>");
}
},
error: function (result) {
alert("fail");
}
})
}
</script>
}

Answer 2

[thanks Yiyi You, ifound the correct answer i doit this way]
[enter image description here][1]
[1]: https://i.stack.imgur.com/KWsIi.png do as folow
displaydata1 = rTDBContext.Turnos.ToList();
var display = displaydata1.DistinctBy(x => x.LocNombre ).ToList();
var displayda = (from c in display
select new SelectListItem { Text = c.LocNombre, Value = c.IdLocalidad + "" }).Distinct().ToList();
now is working as desired.