I am a newbie to Backbone and need help to get and set the models from a nested Json Structure using Backbone

I have a simple model and collection below

**Model:**

```
var PmaslDataModel = Backbone.Model.extend({ });

```

**Collection:**

```
app.PmaslDataCollection = Backbone.Collection.extend({
          url APPLICATION_URL+'aslview/getformatedDataRows',
          model         : PmaslDataModel 
    });

```

**Initialize the collection**

```
var pmaslDataCollection =   new app.PmaslDataCollection();

```

Fetching the above collection returns the data in the Json Format below

```
{
"id"    : "1",
"rowid" : "1",
"group" : "10__",
"datarows": [
             {
               "id": "sspvk_code",
               "default_display": "1",
               "order": "1",

            },
            {
               "id": "sspvk_code2",
               "default_display": "0",
               "order": "0",
           },
           {
               "id": "sspvk_code3",
               "default_display": "1",
               "order": "0",
           }
         ]
},
{
   "id"    : "2",
   "rowid" : "2",
   "group" : "11__",
   "datarows": [
                {
                  "id": "sspvk_code",
                  "default_display": "1",
                  "order": "1",

                },
                {
                   "id": "sspvk_code2",
                   "default_display": "0",
                   "order": "0",
                },
                {
                   "id": "sspvk_code3",
                   "default_display": "1",
                   "order": "0",
                }
            ]
}

```

I have to use the above structure to populate the values in a table where we have the row ids and the column values in the row appears in the datarows attributes 

I have 2 Questions

1. How can I set the "default\_display" value to 0 for all the datarows
with id=sspvk\_code ?
2. If I have a particular row id how can I fetch the datarows for that
row,pass it to a underscore template and populate the template (that
is ,in the template I need to access it with model.get('attributename value')