Angular Type Script undefined error with parent variable

Question

Anyone understand why I am getting an undefined error?

export abstract class BaseEditorComponent implements IPropertyEditor, OnDestroy {

  @Input()
  public element: BpmnJS.IRegistryElement; 

--more code here


export class CommonPropertiesEditorComponent extends BaseEditorComponent {

  constructor(
  ) {
    super();
  }

  public get elementId(): string {
    return this.element.id;
  } 

export class ExclusiveGatewayEditorComponent extends CommonPropertiesEditorComponent implements OnInit {

  public model: IUserTaskDef;
  public outGoing: Sequences[];

  constructor(
    private service: ExclusiveGatewayService
  ) {
    super();
    this.model = {} as any;
    this.outGoing = this.getOutGoingSequences();
  }

  public getOutGoingSequences(): Sequences[] {

    return this.service.getOutgoingSequences(this.elementId); //This is undefined.
  }

TypeError: Cannot read property 'id' of undefined at ExclusiveGatewayEditorComponent.get [as elementId] (common-properties-editor.component.ts:16) at ExclusiveGatewayEditorComponent.push../src/app/properties/editors/gateways/exclusive-gateway/exclusive-gateway-editor.component.ts.ExclusiveGatewayEditorComponent.getOutGoingSequences (exclusive-gateway-editor.component.ts:27) at new ExclusiveGatewayEditorComponent (exclusive-gateway-editor.component.ts:22) at createClass (core.js:21148) at createDirectiveInstance (core.js:21027) at createViewNodes (core.js:29387) at createRootView (core.js:29301) at callWithDebugContext (core.js:30309) at Object.debugCreateRootView [as createRootView] (core.js:29819) at ComponentFactory_.push../node_modules/@angular/core/fesm5/core.js.ComponentFactory_.create (core.js:20506)

If I enter the same function into the html page it works fine and displays the value of element.id

<input class="form-control" type="text" name="txtId" [(ngModel)]="elementId" readonly>

Dark Daskin · Accepted Answer · 2019-12-06 17:20:31Z

1

You should not try to access @Input() properties from constructor, they do not exist at this point. You should do it in ngOnInit() method instead.

export class ExclusiveGatewayEditorComponent extends CommonPropertiesEditorComponent implements OnInit {

  // ...

  constructor(
    private service: ExclusiveGatewayService
  ) {
    super();
    this.model = {} as any;    
  }

  ngOnInit() {
    this.outGoing = this.getOutGoingSequences();
  }
}

answered Dec 6, 2019 at 17:20

Dark Daskin

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