How to cast an object into a two dimensional array in javascript

Question

I know this question may have been asked hundreds of times and that there is tons of examples about and probably I may be downvoted, but I have to ask it any way because I don't know in what side (controller, script or both) my code is incorrect and also b/c I couldn't find an example on how to cast an object into a two-dimensional array (which is what I believe the result is): I need to pass a List> from the MVC controller back to the ajax script, then manipulate the array results, but I don't know how to cast the array to read its elements.

[HttpGet]
public ActionResult ListBoxCustomize(string listName)
   {
      var result = new List<KeyValuePair<string, string>>();  // Key , Value

      // Code to add items to the list 
      .........

      return Json(new { items = result }, JsonRequestBehavior.AllowGet);
}

JScript

$.ajax(
{
    success: function (data) // THIS IS WHAT IS RETURNED -> data = Object {items: Array[5]}
    {
    alert( items[0][0] ) // Reference Error: items is not defined 
    OR
    alert( data[0][0] ) // Uncaught TypeError: Cannot read property "0" of undefined         

    .... and so it goes with all other cast and combinations that I've tried.          

    }

Did you mean to call data.items[0][0] instead of items[0][0]? — creemama
– creemama, Commented Feb 9, 2016 at 21:29

Chris Tavares · Accepted Answer · 2016-02-09 21:29:46Z

1

In your javascript, your parameter is named data but your alert is passed items. What happens if you do alert(items[0][0])? Or break into the debugger in your browser's dev tools and look at the object structure? Another option would be to use a tool like Fiddler to look at the actual response being returned; once you see the data on the wire it's usually pretty straightforward to process it on the client.

answered Feb 9, 2016 at 21:29

Chris Tavares

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3 Comments

Ben Junior Over a year ago

This is what comes back from the controller: data = Object {items: Array[5]} How can I read that?

Chris Tavares Over a year ago

Well, data, is an object with one field named items which is an array of five items. What happens if you do alert(data.items[0])?

Ben Junior Over a year ago

That worked! just needed to add the name like data.items[0].Key

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