Type 'Observable<any>' is missing the following properties from type 'any[]': length, pop, push, join, and 18 more.

[Bob]

As soon as I add the following lines to my component (having first imported "of" from rxjs.

public children = (dataItem: any): any[] => of(dataItem.items);
public hasChildren = (dataItem: any): boolean => !!dataItem.items;

 

I get the folllowing error:

Type 'Observable<any>' is missing the following properties from type 'any[]': length, pop, push, join, and 18 more.

 

How do I implement the children and hasChildren properties?

 

 

 

 

 

[Dimiter Topalov]

Hello Bob,

Indeed, this is a mistake in our demo. Please refer to the correct code snippet:

https://www.telerik.com/kendo-angular-ui/components/treeview/data-binding/#toc-basics

public fetchChildren(node: any): Observable<any[]> {
          //Return the items collection of the parent node as children.
          return of(node.items);
      }

The RxJS "of" function returns an Observable as opposed to a JavaScript array, thus the return type of the "children" method is incorrect (any[]) whereas it has to be Observable<any[]> in this case:

https://stackblitz.com/edit/angular-8ltbyn?file=app/app.component.ts

I apologize for any inconvenience caused, and will fix the demo as soon as possible.

Regards,
Dimiter Topalov
Progress Telerik