CODEWITHSUNDEEP
flutterdartflutter-getx
Naimur Hasan
Naimur Hasan

Reputation: 675

How to assign value to obs in flutter getx

The below code working fine so far,

class Controller extends GetxController{
  var count = 0.obs;
  increment() => count++;
}

But when I assign a value it doesn't work as expected not event with type cast.

class Controller extends GetxController{
  var count = 0.obs;
  reset() => count = 10;
}

I would like to know how to assign value ( with '=' ) in get x obs objects?

Upvotes: 1

Views: 8620

Answers (2)

julemand101
julemand101

Reputation: 31219

This answer has been changed after I have been notified that I was wrong. I want to say thanks to Ivo Beckers to pointing put my misunderstanding of how RxInt works. Please upvote his answer.

0.obs returns the type RxInt. When you call ++ on this object, it is calling the + operator on the RxInt object with 1 to increment the value. It should be noted that the + and - operators for RxInt does manipulate the object itself and does therefore not behave like e.g. int which is immutable and does therefore require the return of a new object from the operation.

When you do count = 10 you are actually saying you want count to be overwritten with 10 which are of the type int and not RxInt.

What you want is more likely to be the following to you can report back to any subscribers that the value have been reset to 10:

class Controller extends GetxController{
  var count = 0.obs;
  reset() => count.value = 10;
}

Upvotes: 7

Ivo
Ivo

Reputation: 23164

To set the value of an RxInt you simple assign it to the value. So you do

reset() => count.value = 10;

The reason why ++ also works is because count++ simply translates to count = count + 1 and this calls the operator on the RxInt instance which simply increases its value as you can see in the implementation of RxInt:

class RxInt extends Rx<int> {
  RxInt(int initial) : super(initial);

  /// Addition operator.
  RxInt operator +(int other) {
    value = value + other;
    return this;
  }

  /// Subtraction operator.
  RxInt operator -(int other) {
    value = value - other;
    return this;
  }
}

Upvotes: 4

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