Angular 2 enum with ngClass

Question

Hello I am trying to use a conditional class with an enum. I have used enums in html before with ngSwitchCase and have the same error that I'm getting now. When I would add a property called that enum and assign it to that enum it would work.

working example:

                    <ng-container *ngFor="let column of columns" [ngSwitch]="column.dataType">
                    <td *ngSwitchCase="DataType.Text">{{getPropertyValue(row,column.propertyName)}}</td>
                    <td *ngSwitchCase="DataType.Date">date</td>
                    <td *ngSwitchCase="DataType.Number">number</td>
                    <td *ngSwitchDefault>default</td>
                </ng-container>

ts

private DataType = DataType;

not working:

            <span *ngClass="(column.sortType === SortType.Ascending)? 'privilege-grid-sortasc': (column.sortType === SortType.Descending)?'privilege-grid-sortdesc':'privilege-grid-sortnone'"></span> 

I also have tried [ngClass] ="{'class-name': var === enum,...}"

ts

   private SortType = SortType;

error message:

Cannot read property 'Ascending' of undefined

Answer 1

I found a really good tutorial here : https://coryrylan.com/blog/angular-tips-template-binding-with-static-types

in summary the syntaxe is [ngClass] ="{'class-name': var === enum}":

@Component({
  selector: 'app-message',
  template: `
    <div class="message" [ngClass]="{
      'message--error': messageTypes.Error === type,
      'message--success': messageTypes.Success === type,
      'message--warning': messageTypes.Warning === type
    }">
      <ng-content></ng-content>
    </div>
  `
})
export class MessageComponent implements OnInit {
  @Input() type = MessageTypes.Default;
  private messageTypes = MessageTypes; //very important to declare here

  constructor() { }

  ngOnInit() { }
}

Answer 2

I think your problem must lie somewhere else. I recreated your scenario using the [ngClass] binding with an enum and it works fine for me:

[ngClass] ="{'class-name': var === enum,...}"

Is your template in the second case on a separate .html file and not in the first case? I've had problems where a private variable on my component file can't be read by the template file.