jquery Convert String to Object

Question

I am trying to create a JSON object from a string in the correct JSON format I received from my .jsp file. I get the string and convert it as follows:

try{
        var jsonStringer = JSON.stringify(mazeFromServer);
        var obj = JSON.parse(jsonStringer);
    }catch (e){
        window.alert(e);
    }

This works without errors. When I try to manipulate or get information from that object, for instance:

var stringName = obj.Name;

Although i have a Name field in my JSON, nothing happens. I checked my JSON on the JSON validation website and everything was fine. What is wrong?

JSON looks like this:

{
        "Name": "Game1",
        "Level":"Two"};

When I declare JSON by myself, it works fine. But when I receive it in a String format from an outside source it doesn't work.

Any Ideas?

EDIT:

mazeFromServer is a string received from an external server. In my servlet i am adding it as follows:

JSONObject obj = new JSONObject();
    obj.put("progress", fromServer);

And then running this Query in my jsp file:

function getMaze(){
    $.getJSON("ProgressServlet", function(data){
        if (data.progress != current)
                mazeFromServer = data.progress;
            $('.mazeLabel').text(mazeFromServer);
        stopJSONCheck();
    })
}

The mazeFromServer Looks as follows:

"Name": "Game1", "Maze": "111111111110000000", "Start": { "Row": 3, "Col": 3 }, "End": { "Row": 1, "Col": 3 } }

please replace JSON object with object. JSON is always a string. — Nina Scholz
– Nina Scholz, Commented May 25, 2016 at 14:03
You're stringifying something which is already a string, then unstringifying the results. Skip the first step. — Daniel Beck
– Daniel Beck, Commented May 25, 2016 at 14:10
Yeah, get rid of var jsonStringer = JSON.stringify(mazeFromServer); and change the obj line to var obj = JSON.parse(mazeFromServer); — Anialation
– Anialation, Commented May 25, 2016 at 14:11
This question is tagged as jQuery (though no jQuery code is shown). That library will normally convert from/to JSON automatically in many circumstances so you'll probably get better answers if you provide some context. — Álvaro González
– Álvaro González, Commented May 25, 2016 at 14:12

SPlatten · Accepted Answer · 2016-05-25 15:15:29Z

1

You should modify your code as follows:

    try{
        var obj;

        if ( typeof mazeFromServer != "string" ) {
            obj = jsonStringer;
        } else {
            var jsonStringer = JSON.stringify(mazeFromServer);

            if ( typeof jsonStringer != "string" ) {
                throw("mazeFromServer cannot be converted to JSON string");
            }   
            obj = JSON.parse(jsonStringer);
        }
        if ( typeof obj != "object" ) {
            throw("'obj' is not an object, it is: " + typeof obj);
        }
    } catch (e) {
        window.alert(e);
    }

edited May 25, 2016 at 15:15

answered May 25, 2016 at 14:21

SPlatten

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14 Comments

user2955610 Over a year ago

It throws: "Cannot JSON string back to object"

SPlatten Over a year ago

Can you post the content of mazeFromServer plz? Try the insertion I posted above before calling stringify.

user2955610 Over a year ago

Throws: "mazeFromServer is not an object"

SPlatten Over a year ago

Modified again, might give you some clue.

user2955610 Over a year ago

Throws: mazeFromServer is not an object, it is: string

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