c# mvc ajax convert list to JSON string

Question

I'm trying to code a simple autocomplete using LINQ to entities and Razor (new to c# sharp as well) and i'm having trouble displaying json data in my view.

My controller is as follows:

public ActionResult AutoCompleteCity(string guess)
{
    List<City> listData = null;                
    if (!string.IsNullOrEmpty(guess))
    {
       listData = db.AutoCompleteCity(guess);
    }                
    return Json(new { Data = listData });                 
}

AJAX call:

function getCities(input) {
    var serviceURL = $("#autocompleteURL").val();    
    var url =
        $.ajax({
            type: "POST",
            url: serviceURL,
            data: {
                'guess': input
            },            
            dataType: 'json',
            success: function (response) {                    
                if (response.Data != null) {
                    if ($("#targetUL") != undefined) {                            
                        $("#targetUL").remove();
                    }                        
                    Data = response.Data;

                    $.each(Data, function (i, value) {                                                  
                        $("#targetUL").append($("<li class='targetLI' onclick='javascript:agregarTexto(this)'>" + JSON.stringify(value) + "</li>"));    
                    });                       
        });
}

I might be missing a bracket or two :D Any way when i retrieve records from the database and try to pass JSON values to the view the output is:

{"Data":[{"Selected":false,"Text":null,"Value":null}]}

I assume I'm not passing the JSON listData correctly. Any input will be greatly appreciated, thanks!

EDIT: here is a screencap of the values returned by listData in my controller

This is my LINQ query

public List<City> AutoCompleteCity(string guess)
        {
            using (var context = new Sports.SportsEntities())
            {
                var query = (from loc in context.city
                             join prov in context.state on loc.STATE_ID equals prov.STATE_ID
                             where loc.CITY_DESC.Contains(guess.ToUpper())
                             select new
                             {
                                 city = loc.CITY_DESC,
                                 state = prov.STATE_DESC,
                             });

                IEnumerable<City> cityList= from ba in query.AsEnumerable()
                                                 select new City(ba.city, ba.state); 

                return cityList.ToList();
            }
        }

You don't need to JSON.stringify(). In the each loop you can use value.Value, value.Selected or value.Text. — Jasen
– Jasen, Commented May 31, 2016 at 17:15
If you put a breakpoint in your MVC action, (a) does the correct value of guess get passed into the action. (b) what is the value of listData at the return statement? — Glenn Ferrie
– Glenn Ferrie, Commented May 31, 2016 at 17:54
@GlennFerrie I added a screenshot to my original post with the values,, thanks! — Juan M
– Juan M, Commented May 31, 2016 at 18:41

Juan M · Accepted Answer · 2016-06-01 16:58:42Z

1

This error:

{"Data":[{"Selected":false,"Text":null,"Value":null}]}

was caused by having declared private attributes in the City Class, or by failing to declare getter/setter methods if said attributes are meant to be private. I figured that out by looking at the screen capture posted on my question, only displaying the "selected", "text" and "value" properties and not the city and state description in the query results, which was what I needed to display below the textbox input.

This controller method will do the trick:

 public JsonResult AutoCompleteCity(string term)
        {
            List<City> listData = new List<City>();
            if (!string.IsNullOrEmpty(term))
            {
                listData = db.AutoCompleteCity(term);
            }

            return Json(listData, JsonRequestBehavior.AllowGet);

        }

answered Jun 1, 2016 at 16:58

Juan M

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Comments

ThomasDB · Accepted Answer · 2016-05-31 17:38:02Z

0

The problem is probably this piece of code in the AJAX call:

if ($("#targetUL") != undefined) {                            
    $("#targetUL").remove();
}

By doing this you are removing the ul tag from the DOM and therefore cannot add the li elements you are constructing in this piece of code:

$.each(Data, function (i, value) {                                                  
    $("#targetUL").append($("<li class='targetLI' onclick='javascript:agregarTexto(this)'>" + JSON.stringify(value) + "</li>"));    
});

If you want to clear the list use .empty():

if ($("#targetUL") != undefined) {                            
    $("#targetUL").empty();
}

answered May 31, 2016 at 17:38

ThomasDB

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1 Comment

Juan M Over a year ago

Thanks for the input! I changed remove() for empty() as suggested but still haven't been able to get correct values

lem2802 · Accepted Answer · 2016-05-31 20:14:50Z

0

if you want to return a JSON, change that:

public ActionResult AutoCompleteCity(string guess)

by

public JsonResult AutoCompleteCity(string guess)

and also try that:

Data = JSON.parse(response.Data);

answered May 31, 2016 at 20:14

lem2802

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1 Comment

Juan M Over a year ago

JsonResult is an ActionResult, from what I've gathered

Sonya · Accepted Answer · 2016-05-31 20:17:07Z

0

It looks like your method returns a list of City objects, so maybe you need to use the property of that objects to get to the city name, something like this:

$.each(Data, function (i, city) {                                                  
$("#targetUL").append($("<li class='targetLI' onclick='javascript:agregarTexto(this)'>" + city.Name + "</li>"));

});

edited May 31, 2016 at 20:17

answered May 31, 2016 at 20:07

Sonya

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