CODEWITHSUNDEEP
arraysdart
flutter
flutter

Reputation: 6786

Convert arrays to properties of a new class using the map operator

I've two arrays/Lists:

users =[object1,object2,object3]; all of the same type: Class User

teams =[object1,object2,object3]; all of the same type: Class Team

I want to create a new array dynamically containing objects of type SupportTeams which has properties of type User and Team.

I think I should use the map operator to convert the arrays to my new array.

Something like this 

List<SupportTeams> combiner(List<User> users, List<Team> teams) {
    return users.map((user) {
      teams.map((team) {
        SupportTeams(user,team);
      });
    }).toList();
  }

Upvotes: 0

Views: 30

Answers (1)

Ben Konyi
Ben Konyi

Reputation: 3219

You're almost there. First thing's first, you need to return from your calls within map:

List<SupportTeams> combiner(List<User> users, List<Team> teams) {
    return users.map((user) {
      return teams.map((team) {
        return SupportTeams(user,team);
      });
    }).toList();
  }

However, this still won't work 100% as you'll have a list of lists. You'll need to flatten the result using expand:

List<SupportTeams> combiner(List<User> users, List<Team> teams) {
    return users.map((user) {
      return teams.map((team) {
        return SupportTeams(user,team);
      });
    }).expand((i) => i).toList();
  }

If you want to be even more concise, you can use => notation instead of returns:

List<SupportTeams> combiner(List<User> users, List<Team> teams) =>
    users.map((user) =>
      teams.map((team) => 
        SupportTeams(user,team))).expand((i) => i).toList();

Finally, as @lrn pointed out in the comments you can use control flow collections to do this much more cleanly:

List<SupportTeams> combiner(List<User> users, List<Team> teams) => [
  for (var user in users)
    for (var team in teams)
      SupportTeams(user, team)
];

Upvotes: 2

Related Questions