know when @Input parameter is changed

Question

I want to exec a function every time when the @Input is changed. I tried to do it that way:

 ngOnChanges(changes: { [propName: string]: SimpleChange }) {
  if( changes['inputName'] && changes['inputName'].previousValue != changes['inputName'].currentValue ) {
    this.func();
  }
}

but my problem is: my @Input value is'nt necessarily changed (it can be "a" and another once "a") but even if it's not changed I want to exec the function. what can I do?

maybe you just get rid of this if statement and just fire this.func() in ngOnChanges body? — Yura Rudnychenko
– Yura Rudnychenko, Commented Jul 2, 2020 at 9:02
it can be a good idea, but i have some inputs, and I want to exec the function only when the specific input is changed. — Tammar
– Tammar, Commented Jul 2, 2020 at 9:19

Gaurang Dhorda · Accepted Answer · 2020-07-02 09:19:29Z

2

You need to call setter method For @Input() changed everytime..

@Input('inputName') set cmpRef (cmp : any){
   // your function call here goes every time @Input() changes, this setter method is called.
      this.func();
 }

answered Jul 2, 2020 at 9:19

Gaurang Dhorda

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3 Comments

Tammar Over a year ago

I tried to do that but the set works only in the first time when the input is changed and not every time.

Gaurang Dhorda Over a year ago

You have to Immutable your object for Input() to work properly, For this you can use destructing or Object.assign()

Gaurang Dhorda Over a year ago

@Tammar If answer is helpul to you, You can accept it. Thank you.

Tammar · Accepted Answer · 2020-07-08 07:08:56Z

0

I solved the problem by putting object in the @Input parameter instead of string only. and now it is changed every time I change it.

answered Jul 8, 2020 at 7:08

Tammar

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