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Flutter – Grouping a list of Objects on Common String Value

I have this Group object

class Group {
      final String dateFormatted;
      final List<Event> events;
    
      Group({required this.dateFormatted, required this.events});
    }

I need to fold the group so that all Groups with common dateFormatted will be merged into the same group and create a new Group Object with that data.

I have the following issue on screen with the current structure

enter image description here

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2

Answers


  1. 0

    Here how you can group common date events

    List<Group> mergeGroups(List<Group> groups) {


// Create a map to group events by dateFormatted
  final Map<String, List<Event>> groupedEvents = {};

  for (var group in groups) {
    if (!groupedEvents.containsKey(group.dateFormatted)) {
      groupedEvents[group.dateFormatted] = [];
    }
    groupedEvents[group.dateFormatted]!.addAll(group.events);
  }

  // Convert the map back to a list of Group objects
  return groupedEvents.entries
      .map((entry) => Group(dateFormatted: entry.key, events: entry.value))
      .toList();
}
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  2. 0 
    List<Group> mergedGroups(List<Group> seperateGroups) {
  List<Group> mergedGroups = [];
  for (var group in seperateGroups) {
    Group isExistingGroup = mergedGroups.firstWhere(
      (g) => g.dateFormatted == group.dateFormatted,
      orElse: () => null,
    );

    if (isExistingGroup != null) {
 isExistingGroup.events.addAll(group.events);
    } else {
      
      mergedGroups.add(Group(
        dateFormatted: group.dateFormatted,
        events: group.events.toList(),
      ));
    }
  }

  return mergedGroups;
}

    This might work. You want to combine a list of group object. Here you pass groups to the function as parameter and it checks whether a group exists with formattedDate or not. If exists, add events to that group else it creates a group. (If your formattedDate has hour:min:s:ms values it does not work. Be sure formattedDate has only year/month/day values.

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