How do I add append to this nested JSON object

Question

My JSON object is

"msg"=[{"userName":"Mandy","emailId":"m@t.co","userCreated":"2011-12-21 17:21:49","allowedDownloads":"15"},{"userName":"Andy","emailId":"ab@r.co","userCreated":"2011-12-21 17:29:58","allowedDownloads":"45"},{"userName":"Randy","emailId":"re@t.co","userCreated":"2012-01-02 10:18:19","allowedDownloads":"15"},{"userName":"Vandy","emailId":"vai@t.co","userCreated":"2012-01-02 15:49:20","allowedDownloads":"14"},{"userName":"Sandy","emailId":"vrush@t.co","userCreated":"2012-01-02 16:47:35","allowedDownloads":"14"}]

1)How do I add 1 more person so that "msg" is appended with

{"userName":"Wendy","emailId":"w@t.co","userCreated":"2012-12-21 17:21:49","allowedDownloads":"15"}

2) How do I add a property "hobbies" to each of these indexes, so that I have,for eg

{"userName":"Wendy","emailId":"w@t.co","userCreated":"2012-12-21 17:21:49","allowedDownloads":"15","hobbies":"skiing,football,hockey"}

3) How do I check whether the index "Wendy" has a hobby "hockey" ?

Answer 1

As you have a Javascript array

  var msg = [{"userName":"Mandy","emailId":"m@t.co","userCreated":"2011-12-21 17:21:49","allowedDownloads":"15"},
             {"userName":"Andy","emailId":"ab@r.co","userCreated":"2011-12-21 17:29:58","allowedDownloads":"45"},
             {"userName":"Randy","emailId":"re@t.co","userCreated":"2012-01-02 10:18:19","allowedDownloads":"15"},
             {"userName":"Vandy","emailId":"vai@t.co","userCreated":"2012-01-02 15:49:20","allowedDownloads":"14"},
             {"userName":"Sandy","emailId":"vrush@t.co","userCreated":"2012-01-02 16:47:35","allowedDownloads":"14"}];

you can easily push a new element

  msg.push({"userName":"Wendy","emailId":"w@t.co","userCreated":"2012-12-21 17:21:49","allowedDownloads":"15"});

but to update a record you have to loop

  function update(username, property, value){

      for(var i=0; i < msg.length; i++){
          var user = msg[i];
          if(user["userName"] == username){
              user[property] = value;
              break;
          }          
      }

  }

to search also you have to loop

  function check(username, property, value){

        for(var i=0; i < msg.length; i++){
            var user = msg[i];
            if(user["userName"] == username){
                var propertyVal = user[property];
                if( propertyVal && propertyVal.indexOf(value) != -1){
                    return true;
                }
            }          
        }
        return false;
    }

Answer 2

1) You can add one more record with:

data.push({"userName" : "Smit","emailId":"smit@example.com","userCreated":"2011-12-21 17:29:58","allowedDownloads":"9"});

2) You can add "hobby" like:

for(a in data)
{
    data[a].hobbies = "skiing,football,hockey";
}

3) For the last question, you can create a function. I'm not so good with javascript, so there might be some other option apart from this. But you can start with this code:

function getHobbey(userName, hobbey_name)
{
    for(a in data)
    {
        if (data[a].userName == userName)
        {
            var hb = data[a].hobbies;
            if (hb != '')
            {
                all_hb = hb.split(",");
                for(i=0; i<= all_hb.length; i++)
                {
                    if (all_hb[i] == hobbey_name)
                    {
                        return true;
                    }
                }
                return false;
            }
            return false;
        }            
    }
}

And by calling that

alert(getHobbey("Smit","skiing"));

Will give you true or false.

Still there are lots of thing in which you can improve this function.

Thanks!