Bloc: [Question] How to correctly sort a list

[VictorUvarov]

Describe the bug
I can't seem to emit more than one state when sorting a list more than once.

To Reproduce
Steps to reproduce the behavior:

1. Create a bloc with a list:

final _users = [
  User(firstName: "Zz", lastName: "Aa"),
  User(firstName: "Aa", lastName: "Zz"),
];

1. Emit an event to sort the list by last name
2. List changes
3. Emit an event to sort the list by first name
4. No state emitted

Workaround
I had to create different states for this to work correctly

BlocState.loaded(users: _users),
BlocState.filteredByFirstName(users: _users),
BlocState.filteredByLastName(users: _users),

Since this is very verbose, I feel like it is probably the wrong approach.

Expected behavior
A new state to be emitted when the list changes more than once.

BlocState.loaded(users: _users), // sorted by first name
BlocState.loaded(users: _users), // sorted by last name

Additional context
I assume the new state is not being emitted because the state is the same, but the list is different? Not sure why it would only emit once.

[narcodico]

Hi @VictorUvarov 👋

You're probably applying the sorting directly which is modifying the existing list so value equality won't work.
Instead do yield List.from(_users)..sort(...);

[VictorUvarov]

I am doing it directly thanks for the advice I'll try it out 🙂

[VictorUvarov]

Thanks @RollyPeres it worked

Solution:

var sorted = List<User>.from(_friends)
      ..sort((a, b) => a.firstName.compareTo(b.firstName));

yield FriendsListState.loaded(friends: sorted);