Type 'string' is not assignable to type 'boolean' about coerce-property HOT 5 CLOSED

You need to specify a string | boolean:
@Input() @coerceBoolean public multiple: string | boolean = false;
This is normal, because for this notation style, the string type from Angular will come, although coerceBoolean will actually always return a boolean

from coerce-property.

You can specify the type more precisely: boolean | '':
@Input() @coerceBoolean public multiple: boolean | '' = false;

from coerce-property.

The problem then is that the property cannot be passed directly to a child component that expects a boolean input.

@Component({
  template: `
    <ng-select [multiple]="multiple"></ng-select>
  `
})
export class TestComponent {
  @Input() @coerceBoolean public multiple: boolean | '' = false;
}

After removing the type definition works it works fine.

@Input() @coerceBoolean public multiple = false;

Edit: Actually, removing the type definition brings back the initial TS2322 error.

from coerce-property.

In your case, you can write:

@Component({
  template: `
    <ng-select [multiple]="multiple || false"></ng-select>
  `
})
export class TestComponent {
  @Input() @coerceBoolean public multiple: boolean | '' = false;
}

from coerce-property.

Probably this is better:

@Component({
  template: `
    <ng-select [multiple]="!!multiple"></ng-select>
  `
})
export class TestComponent {
  @Input() @coerceBoolean public multiple: boolean | '' = false;
}

from coerce-property.