Upon now I always use getx observable declarations like this:
var someString = ''.obs;
var someNumber = 0.obs;
and so on...
But what if some variables don't have an initial value at first, and I actually want them to be null and later change them?
For non null-safe (pre Dart 2.12), you can declare your observable variables like this:
final someVariable = Rx<Type>();
For example:
final someString = Rx<String>();
final someNumber = Rx<int>();
And for null-safety (Dart 2.12 or later), Just use Rxn<Type> instead of Rx<Type>.
For example:
final someString = Rxn<String>();
final someNumber = Rxn<int>();
If you don't have an initial value for your [Rx] value (at the first time), you need to use
final Rx<YourObject?> yourObject = (null as YourObject?).obs;
Or for more organizing your code, you can create a separate class, like this
class RxNullable<T> {
Rx<T> setNull() => (null as T).obs;
}
and use:
final Rx<YourObject?> yourObject = RxNullable<YourObject?>().setNull()
If anyone else does face this problem.
final Rx<YourObject?> yourObject = (null as YourObject?).obs;
will work.
but if there's any message that says "Unnecessary cast. Try removing the cast.", just add this comment
// ignore: unnecessary_cast
above the line, and then save.