Expression has changed after it was checked

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ height:90px;width:728px;box-sizing:border-box;
}

When I call a service in (change) action method , I got this error :

ERROR Error: ExpressionChangedAfterItHasBeenCheckedError: Expression
has changed after it was checked. Previous value: 'ng-untouched:
true'. Current value: 'ng-untouched: false'

My code :

onChange(event) { 



  const messageToDisplay = "Message test";

  this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => {

    if (result === ConfirmPopinResultType.CONFIRM) {

      console.log("test");

    }

  });        

}

onChange is an event handler on an input reactive form (select dropdown list)

<form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form>

The exception error occurs when I call the poppin service on Change event handler (that display a pop up with two button Confirm and Cancel)

thank for your help !

edited Jan 3 at 6:04

asked Jan 2 at 21:13

Abadou

104

1

That's a very common problem with the change detection mechanisms in Angular 2+. Have you had a look at this article?

– FK82
Jan 2 at 21:22

It means you are changing the value of something at the wrong time in angular's lifecycle. Here is a good starting point: angular.io/guide/lifecycle-hooks The solution for many (but not all) lifecycle issues is to put a setTimeout around the assignment to a new variable so instead of foo = bar; you writesetTimeout( () => { foo = bar; }, 0);

– Our_Benefactors
Jan 2 at 21:24

I have tried all solution that i found but still not works :( , I used also setTimout() but it is not working : setTimeout(()=>{ this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } }); });

– Abadou
Jan 2 at 21:44

Please help ! , i am blocked all the day :(

– Abadou
Jan 2 at 21:45

Did you try adding changeDetection: ChangeDetectionStrategy.OnPush, to your component

– Naga Sai A
Jan 2 at 21:55

|
show 3 more comments

When I call a service in (change) action method , I got this error :

ERROR Error: ExpressionChangedAfterItHasBeenCheckedError: Expression
has changed after it was checked. Previous value: 'ng-untouched:
true'. Current value: 'ng-untouched: false'

My code :

onChange(event) { 



  const messageToDisplay = "Message test";

  this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => {

    if (result === ConfirmPopinResultType.CONFIRM) {

      console.log("test");

    }

  });        

}

onChange is an event handler on an input reactive form (select dropdown list)

<form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form>

The exception error occurs when I call the poppin service on Change event handler (that display a pop up with two button Confirm and Cancel)

thank for your help !

edited Jan 3 at 6:04

asked Jan 2 at 21:13

Abadou

104

1

That's a very common problem with the change detection mechanisms in Angular 2+. Have you had a look at this article?

– FK82
Jan 2 at 21:22

It means you are changing the value of something at the wrong time in angular's lifecycle. Here is a good starting point: angular.io/guide/lifecycle-hooks The solution for many (but not all) lifecycle issues is to put a setTimeout around the assignment to a new variable so instead of foo = bar; you writesetTimeout( () => { foo = bar; }, 0);

– Our_Benefactors
Jan 2 at 21:24

I have tried all solution that i found but still not works :( , I used also setTimout() but it is not working : setTimeout(()=>{ this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } }); });

– Abadou
Jan 2 at 21:44

Please help ! , i am blocked all the day :(

– Abadou
Jan 2 at 21:45

Did you try adding changeDetection: ChangeDetectionStrategy.OnPush, to your component

– Naga Sai A
Jan 2 at 21:55

|
show 3 more comments

When I call a service in (change) action method , I got this error :

ERROR Error: ExpressionChangedAfterItHasBeenCheckedError: Expression
has changed after it was checked. Previous value: 'ng-untouched:
true'. Current value: 'ng-untouched: false'

My code :

onChange(event) { 



  const messageToDisplay = "Message test";

  this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => {

    if (result === ConfirmPopinResultType.CONFIRM) {

      console.log("test");

    }

  });        

}

onChange is an event handler on an input reactive form (select dropdown list)

<form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form>

The exception error occurs when I call the poppin service on Change event handler (that display a pop up with two button Confirm and Cancel)

thank for your help !

edited Jan 3 at 6:04

asked Jan 2 at 21:13

Abadou

104

When I call a service in (change) action method , I got this error :

ERROR Error: ExpressionChangedAfterItHasBeenCheckedError: Expression
has changed after it was checked. Previous value: 'ng-untouched:
true'. Current value: 'ng-untouched: false'

My code :

onChange(event) { 



  const messageToDisplay = "Message test";

  this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => {

    if (result === ConfirmPopinResultType.CONFIRM) {

      console.log("test");

    }

  });        

}

onChange is an event handler on an input reactive form (select dropdown list)

<form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form>

The exception error occurs when I call the poppin service on Change event handler (that display a pop up with two button Confirm and Cancel)

thank for your help !

javascript html angular typescript

edited Jan 3 at 6:04

asked Jan 2 at 21:13

Abadou

104

edited Jan 3 at 6:04

asked Jan 2 at 21:13

Abadou

104

edited Jan 3 at 6:04

asked Jan 2 at 21:13

Abadou

104

asked Jan 2 at 21:13

Abadou

104

asked Jan 2 at 21:13

Abadou

104

1

That's a very common problem with the change detection mechanisms in Angular 2+. Have you had a look at this article?

– FK82
Jan 2 at 21:22

It means you are changing the value of something at the wrong time in angular's lifecycle. Here is a good starting point: angular.io/guide/lifecycle-hooks The solution for many (but not all) lifecycle issues is to put a setTimeout around the assignment to a new variable so instead of foo = bar; you writesetTimeout( () => { foo = bar; }, 0);

– Our_Benefactors
Jan 2 at 21:24

I have tried all solution that i found but still not works :( , I used also setTimout() but it is not working : setTimeout(()=>{ this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } }); });

– Abadou
Jan 2 at 21:44

Please help ! , i am blocked all the day :(

– Abadou
Jan 2 at 21:45

Did you try adding changeDetection: ChangeDetectionStrategy.OnPush, to your component

– Naga Sai A
Jan 2 at 21:55

|
show 3 more comments

1

That's a very common problem with the change detection mechanisms in Angular 2+. Have you had a look at this article?

– FK82
Jan 2 at 21:22

It means you are changing the value of something at the wrong time in angular's lifecycle. Here is a good starting point: angular.io/guide/lifecycle-hooks The solution for many (but not all) lifecycle issues is to put a setTimeout around the assignment to a new variable so instead of foo = bar; you writesetTimeout( () => { foo = bar; }, 0);

– Our_Benefactors
Jan 2 at 21:24

I have tried all solution that i found but still not works :( , I used also setTimout() but it is not working : setTimeout(()=>{ this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } }); });

– Abadou
Jan 2 at 21:44

Please help ! , i am blocked all the day :(

– Abadou
Jan 2 at 21:45

Did you try adding changeDetection: ChangeDetectionStrategy.OnPush, to your component

– Naga Sai A
Jan 2 at 21:55

That's a very common problem with the change detection mechanisms in Angular 2+. Have you had a look at this article?

– FK82
Jan 2 at 21:22

It means you are changing the value of something at the wrong time in angular's lifecycle. Here is a good starting point: angular.io/guide/lifecycle-hooks The solution for many (but not all) lifecycle issues is to put a setTimeout around the assignment to a new variable so instead of foo = bar; you writesetTimeout( () => { foo = bar; }, 0);

– Our_Benefactors
Jan 2 at 21:24

I have tried all solution that i found but still not works :( , I used also setTimout() but it is not working : setTimeout(()=>{ this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } }); });

– Abadou
Jan 2 at 21:44

Please help ! , i am blocked all the day :(

– Abadou
Jan 2 at 21:45

Did you try adding changeDetection: ChangeDetectionStrategy.OnPush, to your component

– Naga Sai A
Jan 2 at 21:55

|
show 3 more comments

1 Answer
1

active

oldest

votes

You are listening to DOM element events.

(change)="onChange(item.value)"

And you are receiving an error relative to Angular forms.

Previous value: 'ng-untouched: true'. Current value: 'ng-untouched: false'

The two are in conflict, because the ngModel is tracking changes to the form component. Angular Forms use (ngModelChange) to notify of component changes, and Angular Reactive Forms use valueChanges observables.

You haven't shared where you've attached the (change) event handler, but it's clearly on a form input that is also being used by ngModel.

You should be using (ngModelChange) instead of (change).

answered Jan 3 at 3:53

cgTag

24.5k865114

yes the change event handler is on an form input, i have tried (ngModelChange) instead of (change) but I have the same problem :( , this my template : <form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form> the change event call a service to display a pop up message with two button confirm and cancel.

– Abadou
Jan 3 at 5:52

I add that the problem occurs when I call this service on Change event handler : this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } });

– Abadou
Jan 3 at 6:01

add a comment |

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1 Answer
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1 Answer
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oldest

votes

You are listening to DOM element events.

(change)="onChange(item.value)"

And you are receiving an error relative to Angular forms.

Previous value: 'ng-untouched: true'. Current value: 'ng-untouched: false'

You haven't shared where you've attached the (change) event handler, but it's clearly on a form input that is also being used by ngModel.

You should be using (ngModelChange) instead of (change).

answered Jan 3 at 3:53

cgTag

24.5k865114

yes the change event handler is on an form input, i have tried (ngModelChange) instead of (change) but I have the same problem :( , this my template : <form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form> the change event call a service to display a pop up message with two button confirm and cancel.

– Abadou
Jan 3 at 5:52

I add that the problem occurs when I call this service on Change event handler : this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } });

– Abadou
Jan 3 at 6:01

add a comment |

You are listening to DOM element events.

(change)="onChange(item.value)"

And you are receiving an error relative to Angular forms.

Previous value: 'ng-untouched: true'. Current value: 'ng-untouched: false'

You haven't shared where you've attached the (change) event handler, but it's clearly on a form input that is also being used by ngModel.

You should be using (ngModelChange) instead of (change).

answered Jan 3 at 3:53

cgTag

24.5k865114

yes the change event handler is on an form input, i have tried (ngModelChange) instead of (change) but I have the same problem :( , this my template : <form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form> the change event call a service to display a pop up message with two button confirm and cancel.

– Abadou
Jan 3 at 5:52

I add that the problem occurs when I call this service on Change event handler : this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } });

– Abadou
Jan 3 at 6:01

add a comment |

You are listening to DOM element events.

(change)="onChange(item.value)"

And you are receiving an error relative to Angular forms.

Previous value: 'ng-untouched: true'. Current value: 'ng-untouched: false'

You haven't shared where you've attached the (change) event handler, but it's clearly on a form input that is also being used by ngModel.

You should be using (ngModelChange) instead of (change).

answered Jan 3 at 3:53

cgTag

24.5k865114

You are listening to DOM element events.

(change)="onChange(item.value)"

And you are receiving an error relative to Angular forms.

Previous value: 'ng-untouched: true'. Current value: 'ng-untouched: false'

You haven't shared where you've attached the (change) event handler, but it's clearly on a form input that is also being used by ngModel.

You should be using (ngModelChange) instead of (change).

answered Jan 3 at 3:53

cgTag

24.5k865114

answered Jan 3 at 3:53

cgTag

24.5k865114

answered Jan 3 at 3:53

cgTag

24.5k865114

answered Jan 3 at 3:53

cgTag

24.5k865114

yes the change event handler is on an form input, i have tried (ngModelChange) instead of (change) but I have the same problem :( , this my template : <form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form> the change event call a service to display a pop up message with two button confirm and cancel.

– Abadou
Jan 3 at 5:52

I add that the problem occurs when I call this service on Change event handler : this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } });

– Abadou
Jan 3 at 6:01

add a comment |

yes the change event handler is on an form input, i have tried (ngModelChange) instead of (change) but I have the same problem :( , this my template : <form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form> the change event call a service to display a pop up message with two button confirm and cancel.

– Abadou
Jan 3 at 5:52

I add that the problem occurs when I call this service on Change event handler : this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } });

– Abadou
Jan 3 at 6:01

yes the change event handler is on an form input, i have tried (ngModelChange) instead of (change) but I have the same problem :( , this my template : <form [formGroup]="poolForm"> <select id="pool-select" #item (change)="item.value = onChangePool(item.value)" formControlName="item"> <option *ngFor="let item of items" [value]="item.name">{{ item.name }}</option> </select> </form> the change event call a service to display a pop up message with two button confirm and cancel.

– Abadou
Jan 3 at 5:52

I add that the problem occurs when I call this service on Change event handler : this.popinService.open(messageToDisplay).subscribe((result: ConfirmPopinResultType) => { if (result === ConfirmPopinResultType.CONFIRM) { console.log("test"); } });

– Abadou
Jan 3 at 6:01

add a comment |

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