Warn against AsyncNotifier.update misuses

[rrousselGit]

class Example extends AsyncNotifier<int> {
 ...

  void fn() {
    state = AsyncLoading(); // KO, "update" will likely never complete
    update((data) => ...);
  }

  void fn() {
    update((data) {
      state = AsyncLoading(); // OK
       ...
    });
  }


  void fn() {
    update((unused) => ...); // the parameter should be used. Otherwise use AsyncValue.guard
  }

}

[yknevenky]

@rrousselGit

I am trying to update the state of a FamilyAsyncNotifier partially, I just want to know whether I am doing it right. Also in this case of updating a asyncvalue partially, I want to know what's differences in using whenData, AsyncGuard.value and update method . It would be a immense help, if you provide some clarity on this.

Example

The state here is a freezed class and looks something like this

College(
name: "",
students: [],
faculties: [],
departments: []
)

All the above properties are not updated in a one go, for example the below code tries to update the students property while retaining the other values to its previous value.

update((state) async {
      List<Student> students =
          await getStudentsByCollegeId(id: this.arg);
      return state.copyWith(students: students);
});

Am I doing it right or it needs correction.