Flutter/Dart how to groupBy list of maps

Question

I have this list of maps.

[
    {title: \'Avengers\', release_date: \'10/01/2019\'},
    {title: \'Creed\', release_date: \'10/01/2019\'}
    {title: \'Juman         


        

Answer 1

The package collection implements the groupBy function.

For grouping by date:

import "package:collection/collection.dart";

main(List args) {
  var data = [
    {"title": 'Avengers', "release_date": '10/01/2019'},
    {"title": 'Creed', "release_date": '10/01/2019'},
    {"title": 'Jumanji', "release_date": '30/10/2019'},
  ];


  var newMap = groupBy(data, (obj) => obj['release_date']);

  print(newMap);
}

For removing the release_date key from each map entry:

var newMap = groupBy(data, (obj) => obj['release_date']).map(
    (k, v) => MapEntry(k, v.map((item) { item.remove('release_date'); return item;}).toList()));

For changing a key:

var newMap = groupBy(data, (obj) => obj['release_date']).map(
    (k, v) => MapEntry(k, v.map((item) => {'name': item['title']}).toList()));