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JSON-data get undefined as result. How to get JSON-data?

I have a dataset with location-data. And in the GetLocation the data are transformed in a latitude and longitude value. That works fine. But when I returned to the html-page. The data is undefined. What is the reason? And how can I resolve this with JSon-data?
[HttpGet]
public JsonResult GetLocation(Dictionary<string, string> items)
{
var result = "{ 'latitude': '" + latitude + "', 'longitude': '" + longitude + "'}";
return Json(result);
}
in the html:
if (item.Location == null) {
$.ajax({
url: "#Url.Action("GetLocation", "Home")",
dataType: "json",
data: { items: item },
type: "GET",
success: (function (data) {
location = JSON.parse(data);
})
});
console.log("location:");
console.log(location);

You are double-encoding the JSON here. The Json() function in the action method is encoding the string as JSON, which means the Javascript will be receiving something like this (note the quotes around the entire thing):
"{ 'latitude': '50.69093', 'longitude': '4.337744'}"
You should instead do something like this:
return Json(new { latitude, longitude }, JsonRequestBehavior.AllowGet);
Now in your success function, you will be able to access the values:
success: (function (data) {
location = JSON.parse(data);
console.log(location.latitude);
})
Note also the addition of JsonRequestBehavior.AllowGet, see here for why that is needed.

Please change like below
in MVC return type:
return Json(new { result = result }, JsonRequestBehavior.AllowGet);
in JQuery AJAX
location = JSON.parse(data.result);

Ajax call with parameter as local variables is not working

I have defined a webMethod in code behind as follows.
[System.Web.Services.WebMethod]
public static string testCall(int qid, String answerContent)
{
log.Debug("this is call from jquery" + qid.ToString() + answerContent);
return "true";
}
I am trying to call this method via ajax call in jquery as below.
<script>
$(".submitBtn").click(function (e) {
alert(this.id);
var qID = this.id;
$.ajax({
type: "POST",
url: '/default.aspx/testCall',
data: '{ "qid":' + qID + ', "answerContent":"test" }',
contentType: "application/json; charset=utf-8",
success: function () {
},
failure: function (response) {
alert("fail");
},
dataType: 'html'
});
});
</script>
But this is not working.
However is I pass hardcoded values for parameters as below, it works fine.
data: '{ "qid":"1234", "answerContent":"test" }'
But with var qID passing as parameter not working

Don't hand-assemble JSON. You will get bitten by characters you don't expect in strings, you'll miss out delimiters, etc.
Instead, use the JSON stringifier:
data: JSON.stringify({qid: qID, answerContent:"test"}),
If the ID value is really a number (you're receiving it as an int), you'll want to parse it (as this.id is a string):
data: JSON.stringify({qid: +qID, answerContent:"test"}),
// ------------------------^
...but your hardcoded example that you said works uses a string for the ID, so...

You should use this line as:
data: '{ "qid": "' + qID + '", "answerContent":"test" }'

Converting Javascript JSON to .NET integer array

I was trying to pass json data to .net mvc controller. it seems like mvc automatically converted id and lastdatetime to correct format, but not int[] currentIds, anyone know why?
var jsonData = {
"id": id,
"lastDataTime": lastDateTime,
"currentIds": [1, 2, 3, 4]
};
public void Process(int id, DateTime lastDateTime, int[] currentIds)
{
}

Please try this:
$.ajax({
type: "POST",
url:"#Url.Action("Index", "Home")" ,
data: {
"id": id,
"lastDataTime": lastDateTime,
"currentIds": [1, 2, 3, 4]
},
dataType: "json",
traditional: true,
success: function(msg){
alert(msg)
}
});
public ActionResult Index(int id, DateTime lastDateTime, int[] currentIds)
{
}

Simplify this problem and get the array working first, try this:
View
var myArray = ["1", "2", "3","4"];
$.ajax(
{
type: "POST",
url: '/ControllerName/ActionMethod/',
data: JSON.stringify(myArray),
cache: false,
//dataType: "html",
success: ///
})
Controller
public ActionResult Index(List<String> currentIds)
{
///
}
Debug this and check the list is populated then introduce the other objects.

Passing IEnumerable parameter to WebAPI

I'm getting started with WebAPI and for the most part all is going well. I'm running into a problem with one particular function. This one differs from the other because it's only parameter is of type IEnumerable.
I've set a breakpoint on the first line of the Post() function and I'm hitting the function but the "values" parameter ALWAYS has a count of 0. I verified that the parameter going in on the client side does, in fact, contain an array of integers. If I remove the [FromUri] attribute, the 'values' parameter is NULL instead of a count of 0.
How do I get my array of integers to come through on my WebAPI function?
Here's the WebAPI function:
[System.Web.Mvc.HttpPost]
public void Post([FromUri] IEnumerable<int> values)
{
if (values == null || !values.Any()) return;
int sortorder = 1;
foreach (int photoId in values)
{
_horseRepository.UpdateSortOrder(photoId, sortorder);
sortorder++;
}
}
Here's the AJAX call (this is using the jQuery UI Sortable feature):
$(".sortable").sortable({
update: function (event, ui) {
var newArray = $(".sortable").sortable("toArray");
$.ajax({
url: '/api/photo',
type: 'POST',
contentType: 'application/json, charset=utf-8',
async: true,
dataType: 'json',
data: JSON.stringify(newArray),
complete: function (data) { }
});
}
});

contentType: 'application/json, charset=utf-8',
should become (the separator between the content type and the charset is a semicolon, not a comma):
contentType: 'application/json; charset=utf-8',
and:
public void Post([FromUri] IEnumerable<int> values)
should become (there are no Uri parameters in a POST request):
public void Post(IEnumerable<int> values)
Now you are good to go assuming that newArray (which you haven't shown here) is an array of integers:
newArray = [ 1, 2, 3 ]

how to get data from json?

I have controller
var subCategories = m_listsRepository.GetSubCategories(id);
var items = subCategories.Select(x=>new MyDataNameAndId(){Id = x.Value, Name = x.Text});
return Json(items);
And ajax:
$.ajax({
url: urlString,
type: 'POST',
data: JSON.stringify({ id: districtId }),
dataType: 'json',
contentType: 'application/json',
cache: 'false',
success: function (data) {
alert("success");
$.each(data, function (key, MyDataNameAndId) {
alert(key);//== 0
alert(MyDataNameAndId);// then throws
$('select#ChangeOnsubCategoryId').append('<option value="0">Select One</option>');
$.each(MyDataNameAndId, function (index, manager) {
$('select#ChangeOnsubCategoryId').append(
'<option value="' + manager.Id + '">'
+ manager.Name +
'</option>');
});
});
}
});
what am I doing wrong?
UPDATE:
Controller is worked.
alert("success"); - is show
alert(key); - is show 0
alert(MyDataNameAndId); - not show.
I need generate in 'select#ChangeOnsubCategoryId' options from select#ChangeOnsubCategoryId
How do this? this understand?
I do not know how to show what passed json
json string:
[{"Id":"53","Name":"футбол"}]

From the JSON output you've written out, I'd rewrite it a little bit like this:
$.ajax({
url: urlString,
type: 'POST',
data: JSON.stringify({ id: districtId }),
dataType: 'json',
contentType: 'application/json',
cache: 'false',
success: function (data) {
if (!data) return; // if data is empty, return
var $select = $('select#ChangeOnsubCategoryId');
// put the select element in a variable so you don't need to
// jquery select it again
$select.append('<option value="0">Select One</option>');
// I guess you first want to add a "select one" option
// data should be an array e.g. [{"Id":"53","Name":"футбол"}]
$.each(data, function (key, manager) {
// for each "manager" in the "data" array
// manager should be an object in the data
// array e.g. {"Id":"53","Name":"футбол"}
// no need to for each it
$select.append(
'<option value="' + manager.Id + '">'
+ manager.Name +
'</option>');
// add the manager in the select box
});
}
});
I'm assuming stuff though. Use a javascript debugger (such as developer tools in Chrome or Firebug in Firefox) to check what values you get from the ajax call. Put the breakpoint inside the function and then watch what the data becomes (in this case it should be an array of objects containing Id and Name).

$.each(MyDataNameAndId, function (index, manager) {
$('select#ChangeOnsubCategoryId').append(
'<option value="' + manager.Id + '">'
+ manager.Name +
'</option>');
});
should be just
$('select#ChangeOnsubCategoryId').append(
'<option value="' + MyDataNameAndId.Id + '">'
+ MyDataNameAndId.Name +
'</option>');
The sample code works for me without exceptions which leads me to believe there's something wrong with the JSON being returned. Check that it actually returns the string you posted.