Dart: How to create new list Using Existing List?

Issue

i am new to flutter . I am trying to create new list from below list

 var itemlist1=[
          {"p_id": "a101", "model": "M-Plaz","price": 2500},
          {"p_id": "a101", "model": "Z-Plaz","price": 3500},
          {"p_id": "a102", "model": "M-Neo", "price": 1560},
          {"p_id": "a102", "model": "N-Neo1","price": 3600}];

Output list should be like below

var newlist=[{"Subitems":[
    {
        "p_id":"a101",
        "items": [
            {"p_id": "a101", "model": "M-Plaz","price": 2500},
          {"p_id": "a101", "model": "Z-Plaz","price": 3500}     
        ]},{
        "p_id": "a102",
        "items": [
           {"p_id": "a102", "model": "M-Neo", "price": 1560},
          {"p_id": "a102", "model": "N-Neo1","price": 3600}
        ]},
    ]
}];

please i need help..

Solution

The below code gives you the required output.

var itemlist1 = [
      {"p_id": "a101", "model": "M-Plaz", "price": 2500},
      {"p_id": "a101", "model": "Z-Plaz", "price": 3500},
      {"p_id": "a102", "model": "M-Neo", "price": 1560},
      {"p_id": "a102", "model": "N-Neo1", "price": 3600}
    ];

    var newlist = groupBy(itemlist1, (Map obj) => obj['p_id']);

    var requiredOutput = [
      {"Subitems": []}
    ];
    newlist.forEach((k, v) => {
          requiredOutput[0]["Subitems"]!.add({"p_id": k, "items": v})
        });

    print(requiredOutput);

Note: Add import "package:collection/collection.dart"; line in imports.

Answered By - nagendra nag