"data": [
  {
   "label": "dataName",
   "sections": [
     {
      "label": "label sections 1",
      "fields": [
         {
          "id": 1,
          "name": "field 1",
          "value": "value field 1"
         },
         {
          "id": 2,
          "name": "field 2",
          "value": "value field 2"
         }
        ]
      },
    {
      "label": "label sections 2",
      "fields": [
        {
         "id": 5,
         "name": "field 3",
         "value": "value field 3"
        }
       ]
     }
   ]

array [
      {id: field.id, name: field.name, value: field.value }
      {id: field.id, name: field.name, value: field.value }
  ]

_.each(data, function (elt) {
            _.each(elt.ections, function (elt) {
            ....
         })
     });