CODEWITHSUNDEEP
javascriptjqueryjson
coder25
coder25

Reputation: 2393

Undefined Error in parsing JSON in ajax function in .NET MVC

Jquery 

$('#PostComment').click(function () {

             var commentTitle = $('#commentTitle').val();
             var commentClob = $('#commentClob').val();
             var id = $('#topicId').val();
             var buttoname = $('#PostComment').val();
             var obj;
             $.ajax({

                 type: "post",
                 url: "../../Handler/Topic.ashx",

                 data: "commentclob=" + commentClob + "&commenttitle=" + 
                        commentTitle + "&topicId=" + id + "&Button=" + buttoname,
                 success: function (msg) {

                     try {
                          alert(msg);
                         obj = jQuery.parseJSON(msg);
                         alert("Correct" + obj.CommentClob);

                     }
                     catch (e) {


                         alert("Incorrect" + e.Description + e.ErrorNumber);
                     }



                 }
             });

             return false;
         });
     });

Topic.ashx -ProcessRequest method

     CommentModel cm = daoobject.populateCommentModel(listcommentsbytopic);
     var json= cm.CreateCommentJson();
     context.Response.Write(json);

Function definition

     public string CreateCommentJson()
         {
            // serialize the names to JSON
            var jss = new JavaScriptSerializer();

            var json = jss.Serialize(this);
            return json;
        }

I am getting output 2 alert boxes

first is

 { "UserId": "1", "ToipicId": "44f94c32-c415-4751-812a-03b775775698", "CommentId": "0f1014a0-08d9-48f7-9a0c-d9d6b3d841b2", "CommentClob": "ilikeit", "CommentTitle": "nice", "DescriptionClob": null, "DateCreated": "/Date(1333233498780)/", "Datemodified": "/Date(-62135596800000)/" }

and second is

Incorrect undefined undefined

Can anyone help.

Upvotes: 4

Views: 3504

Answers (4)

g19fanatic
g19fanatic

Reputation: 10961

Your returned json is malformed. You should not be escaping all of the " as you are.

Run your json response msg through http://jsonlint.com and then run this one through it.

{
    "UserId": "1",
    "ToipicId": "44f94c32-c415-4751-812a-03b775775698",
    "CommentId": "0f1014a0-08d9-48f7-9a0c-d9d6b3d841b2",
    "CommentClob": "ilikeit",
    "CommentTitle": "nice",
    "DescriptionClob": null,
    "DateCreated": "/Date(1333233498780)/",
    "Datemodified": "/Date(-62135596800000)/"
}

Follow on:

In your comments, you state that you are getting the first alert printed out. If you are getting it printed out as you say, then that shows that the data is still in string format and NOT already parsed as json. If it were already parsed as json, you'd be getting an [Object object] message instead of the actual text.

That being said, check out this jsFiddle and this resulting screenshot of a Firebug breakpoint.

This essentially shows that the .parseJSON() function will properly parse this new 'json string'. From what you've given us, it tells me that you haven't given us everything. You are doing something (possible typo?, more processing that isn't getting posted?, something!) to that string (if in fact you are getting it as stated) before you parse it with JQuery.

Upvotes: 4

Mustafa Amin
Mustafa Amin

Reputation: 70

I think you are parsing listcommentsbytopic to json twice.

first time here:

CommentModel cm = daoobject.populateCommentModel(listcommentsbytopic);
var json= cm.CreateCommentJson();
context.Response.Write(json);

second time here:

obj = jQuery.parseJSON(msg);

above line is not needed

when you are sending json data from server why are you not using

dataType: 'json'

in below function

$('#PostComment').click(function () {
         var commentTitle = $('#commentTitle').val();
         var commentClob = $('#commentClob').val();
         var id = $('#topicId').val();
         var buttoname = $('#PostComment').val();
         var obj;
         $.ajax({

             type: "post",
             url: "../../Handler/Topic.ashx",

             data: "commentclob=" + commentClob + "&commenttitle=" + 
                    commentTitle + "&topicId=" + id + "&Button=" + buttoname,

             dataType: 'json',  /// this one expect data in json format

             success: function (msg) {

                 try {
                      alert(msg);
                     obj = jQuery.parseJSON(msg);
                     alert("Correct" + obj.CommentClob);

                 }
                 catch (e) {


                     alert("Incorrect" + e.Description + e.ErrorNumber);
                 }



             }
         });

         return false;
     });
 });

Upvotes: 0

ShankarSangoli
ShankarSangoli

Reputation: 69915

Your json is not an array it is a key value pair object.

There is a run time error on this line alert("Correct" + obj[0].CommentClob). Change this line to alert("Correct" + obj.CommentClob);

As a side note, in order to get the error message from exception object(e) use e.message or e.description and for error number use e.number. Since JavaScript is case sensitive e.Description or e.Number will give you undefined value.

Working demo - http://jsfiddle.net/MuEYt/

Upvotes: 0

Gabriele Petrioli
Gabriele Petrioli

Reputation: 196236

Use obj.CommentClob instead of obj[0].CommentClob as the json is not an array..

Additionally you can give another option dataType: 'json' to the .ajax() call and have jQuery handle the parsing.. (or use $.getJSON() directly)

Upvotes: 0

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