How to parse complex json Data in flutter

Question

I have a response for local json object is like

{
    dataKey1: [
      {
        key1: value1,
        key2: value2,
        key3: value3,
      } 
    ],
    dataKey2: [
      {
        key1: value1,
        key2: value2,
        key3: value3,
      } 
    ],
    dataKey3: [
      {
        key1: value1,
        key2: value2,
        key4: value3,
      } 
    ] 
}

I want to display key name (like dataKey1, dataKey2) as a list and by tapping that list It should show in the nested key-value data in grid view.