CODEWITHSUNDEEP
flutterdart
Salma
Salma

Reputation: 1280

async map doesnt reflect changes in the method body

The list returned from this code is empty. assume that formatUser is an async method that formats the user from the remote to a suitable format. why is that filterUsers list does'nt change when we map the other list?

Future<List<User>> fetchUsers() async{
final list<User> usersFromRemote = await getUserFromRemote();

final List<User> filterUsers = [];

usersFromRemote.map((user) async {
   if(user.name != 'jim')
{
     filterUsers.add(await formatUser(user));
}
});

return filterUsers;

}

Upvotes: 0

Views: 48

Answers (2)

Jalil Compaor&#233;
Jalil Compaor&#233;

Reputation: 404

Use forEach() instead of map(). According to the docs, unless the iterable returned by map() is iterated over, the transforming function will not be called.

Upvotes: 0

Chenna Reddy
Chenna Reddy

Reputation: 2341

You are using map wrongly. You need to use filter(aka where) and map for your use case. 

Future<List<User>> fetchUsers() async {
  final List<User> usersFromRemote = await getUserFromRemote();

  final List<User> filterUsers = await Future.wait(
    usersFromRemote.where((u) => u.name != 'jim').map(
      (user) async {
        return formatUser(user);
      },
    ),
  );
  return filterUsers;
}

Or you can use forEach but which is not very functional.

Upvotes: 1

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