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Binding the Angular Data TreeList to OData

The Kendo Angular TreeList has representational functionality and is indifferent to where its data comes from and how it is retrieved and/or updated. This allows you to use any remote data source including the OData v4 protocol.

The following step-by-step guide shows how to bind the TreeList by using the OData v4 protocol:

Create a method to fetch the parent and child nodes based on an index.

 public query(reportsTo: number): Observable<Employee[]> {
     if (reportsTo === 0) {
      return this.http
        .get(`${this.serviceUrl}/TopEmployees/`)
        .pipe(map((data: any) => <Employee[]>data.value));
    } else {
      return this.http
        .get(`${this.serviceUrl}/EmployeeSubordinates(${reportsTo})`)
        .pipe(map((data: any) => <Employee[]>data.value));
    }
}

Get the data from the server and bind the TreeList to the obtained collection.

public treelistData: Observable<Employee[]>;
public ngOnInit(): void {
    this.treelistData = this.query(0);
}

Set the data input property of the component to an Observable. Once the data is received from an asynchronous source, pipe it through the async pipe.

html

<kendo-treelist
    [data]="treelistDataData | async"
    [fetchChildren]="fetchChildren" ... >
    <kendo-treelist-column field="FirstName" title="First Name"></kendo-treelist-column>
    ...
</kendo-treelist>

To fetch the children nodes, initiate a server request with the corresponding index in fetchChildren callback.

public fetchChildren = (item: Employee): Observable<Employee[]> => {
    return this.query(item.EmployeeID);
};

The following example demonstrates how to bind the TreeList using the OData v4 protocol.

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Binding the Angular Data TreeList to OData

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