You cannot prevent this behavior, but you can:
Use a Subject :
class Foo implements OnChanges,OnInit,OnDestroy{
onChanges = new Subject<SimpleChanges>();
ngOnInit(){
this.onChanges.subscribe((data:SimpleChanges)=>{
// only when inited
});
}
ngOnDestroy(){
this.onChanges.complete();
}
ngOnChanges(changes:SimpleChanges){
this.onChanges.next(changes);
}
}
Use a boolean property:
class Foo implements OnChanges,OnInit{
initialized=false;
ngOnInit(){
// do stuff
this.initialized = true;
}
ngOnChanges(changes:SimpleChanges){
if(this.initialized){
// do stuff when ngOnInit has been called
}
}
}
Use the SimpleChanges
API
You can also check the SimpleChange.isFirstChange()
method :
isFirstChange() : boolean
Check whether the new value is the first value assigned.
class Foo implements OnChanges,OnInit{
@Input()
bar:any;
ngOnInit(){
// do stuff
}
ngOnChanges(changes:SimpleChanges){
if(!changes["bar"].isFirstChange()){
// do stuff if this is not the initialization of "bar"
}
}
}
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