angular - Reactive forms - disabled attribute

Question

I am trying to use the disabled attribute from a formControl. When I put it in the template, it works:

<md-input formControlName="id" placeholder="ID" [disabled]="true"></md-input>

But the browser alerts me:

It looks like you're using the disabled attribute with a reactive form directive. If you set disabled to true when you set up this control in your component class, the disabled attribute will actually be set in the DOM for you. We recommend using this approach to avoid 'changed after checked' errors.

  Example: 
  form = new FormGroup({
    first: new FormControl({value: 'Nancy', disabled: true}, Validators.required),
    last: new FormControl('Drew', Validators.required)
  });

So I put it in the FormControl, and deleted from the template:

constructor(private itemsService: ItemsService) {
    this._items = [];
    this.myForm = new FormGroup({
        id: new FormControl({value: '', disabled: true}, Validators.required),
        title: new FormControl(),
        description: new FormControl()
    });
    this.id = this.myForm.controls['id'];
    this.title = this.myForm.controls['title'];
    this.description = this.myForm.controls['description'];
    this.id.patchValue(this._items.length);
}

But it does not work (it is not disabling the input). What is the problem?

Answer 1

I have been using [attr.disabled] because I still like this template driven than programmatic enable()/disable() as it is superior IMO.

Change

<md-input formControlName="id" placeholder="ID" [disabled]="true"></md-input>

to

<md-input formControlName="id" placeholder="ID" [attr.disabled]="true"></md-input>

If you are on newer material change md-input to mat-input.