Question

任何人都明白为什么我会收到未定义的错误吗？

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：无法读取未定义的属性“ id” 在ExclusiveGatewayEditorComponent.get [作为elementId]（common-properties-editor.component.ts：16）在ExclusiveGatewayEditorComponent.push ../ src / app / properties / editors / gateways / exclusive-gateway / exclusive-gateway-editor.component.ts.ExclusiveGatewayEditorComponent.getOutGoingSequences （独家网关编辑器.component.ts：27）在新的ExclusiveGatewayEditorComponent（exclusive-gateway-editor.component.ts：22）在createClass（core.js：21148）在createDirectiveInstance（core.js：21027）在createViewNodes（core.js：29387）在createRootView（core.js：29301）在callWithDebugContext（core.js：30309）在Object.debugCreateRootView [作为createRootView]（core.js：29819）在ComponentFactory_.push ../ node_modules/@angular/core/fesm5/core.js.ComponentFactory_.create （core.js：20506）

如果我在html页面中输入相同的功能，则可以正常工作并显示element.id的值

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

Answer 1

您不应尝试从构造函数访问@Input()属性，因为这些属性目前不存在。您应该改为使用ngOnInit()方法。

export class ExclusiveGatewayEditorComponent extends CommonPropertiesEditorComponent implements OnInit {

  // ...

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

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

带有父变量的Angular Type脚本未定义错误

1 个答案: