Как распарсирить такой json в CI?

[{"kind":24,"val":"2","day":1},{"kind":24,"val":"2","day":2},{"kind":24,"val":"2","day":3}]

var data_array = new Array();
    $("input[type='checkbox']").each(function(){
       var item = {};
        for(var i in $(this).data()){
            item[i] = $(this).data(i);
            item['val'] = $(this).val();
        }
        data_array.push(item);
    });
var data = JSON.stringify(data_array);
$.ajax({
    type:"POST",
    url:"/welcome/savejournal",
    contentType : "application/json",
    data: data,
    success:function(data){ console.log(data); },
      error:function(data){console.warn(data);}
    })