Angular 9, strict templates, incompatible types build errors

[esp]

After enabling the strictTemplates compiler option in Angular 9 I am seeing a number of build errors with the TreeView. The all amount to the same issue of incompatible types, for instance relating to the children property:

 

error TS2322: Type '(node: MyType) => Observable<MyType[]>' is not assignable to type '<T>(item: T) => Observable<any[]>'

 

Not sure what the correct resolution is here.

[Martin]

Hi,

Thank you for the provided feedback.

It seems that the TypeScript does not recognize the types, set in our code. I consulted this issue with the assigned developer and I can assure you that we will investigate further modify the defined types in the implementation of the TreeView. 

Also, I have also updated your account Telerik points for bringing this issue to our attention.

Here is an example that reproduces the reported error:

https://stackblitz.com/edit/angular-yu1fov?file=app/app.component.ts

A workaround that I can provide is to set the fetchChildren argument type to any:

  public fetchChildren(node: any): Observable<any[]> {
    return of(node.items);
  }

Feel free to contact us back if any further questions come up and accept our apologies for the caused inconvenience until the issue is resolved.

Regards,
Martin
Progress Telerik

[Jordan]

hello, any resolution to this issue? I am getting the same error when I use strict mode in an angular project.
In the mean time, for a workaround: if I combine
"strictTemplates": true,
"strictInputTypes": false
the errors go away. Mine is appearing on the width size of the grid column

[Martin]

Hi Jordan,

The initial issue with the TreeView component seems to be resolved. Reusing the same template (as the one used here), but with the latest Kendo package versions (TreeView - v5.3.1), doesn't throw any type errors:

https://stackblitz.com/edit/angular-nb8tkq?file=app%2Fapp.component.ts

Regarding your scenario, I assume that the Grid component is used and the width property is bound like:

   <kendo-grid-column field="ProductID" title="ID" width="40" [filterable]="false">

    </kendo-grid-column>

Please could you try surrounding the width input with square brackets like:

   <kendo-grid-column field="ProductID" title="ID" [width]="40" [filterable]="false">

    </kendo-grid-column>

 

and check if the errors are gone. Also please refer to the following thread for related  type errors when using the State object:

https://www.telerik.com/forums/is-kendo-ui-compatible-with-angular-s-strict-mode

Regards,
Martin
Progress Telerik

 

[Luis]

Hello,

 

I still have the error on the kendo grid.

 

Any suggestion to solve this using the strictTemplates?

 

Thanks

[Martin]

Hi Luis,

Please check the following forum thread where similar questions are discussed:

https://www.telerik.com/forums/is-kendo-ui-compatible-with-angular-s-strict-mode

Regards