How to set formControl default value but prevent to affect observable subscription

I had this thing that was actually pretty logical: A book was gathered via the API. An ionic switch was watching for changes (observable). But I also had to set the default logic: is this user subscribed to the book already? Once I had set this default value, it also went to my observable.

Solution

this.favoritedControl.patchValue(true, {emitEvent: false});

you can call .patchValue({ ... }, { emitEvent: false }) if you wish to skip this initial setup when subscribing to form's valueChanges stream