Tree View No records to display

[Mariusz]

Hi Telerik Team

I’m using ASP.NET CORE (.NET7) with
Telerik.UI.for.AspNet.Core Version="2023.1.425"

I'm trying to use TreeView and it always displays text:   No records to display

My Code:

I configured json options

--- Program.cs --------------------------------------------------------------------------------------------
builder.Services.AddControllersWithViews()
    .AddJsonOptions(options => {
        options.JsonSerializerOptions.PropertyNamingPolicy = null;
                });

----- Controller -------------------------------------------------------------------------------------------

public JsonResult GetTestTreeViewData([DataSourceRequest] DataSourceRequest request)
    {
        var result = GetDirectory().ToTreeDataSourceResult(request,
            e => e.ObjectId,
            e => e.ParentId,
            e => e
        );
        return Json(result);
    }


    private IEnumerable<TreeViewTest> GetDirectory()
    {
        return Enumerable.Range(start: 1, count: 10).Select(i => new TreeViewTest
        {
            ObjectId = i,
            ObjectName = "Object Name " + i,
            ParentId = i - 1,
            ParentName = "Parent Name " + (i - 1)
        });
    }

--- View -------------------------------------------------------------------------------------------

@using Kendo.Mvc.UI
@using MwTech.Domain.Entities;


@(Html.Kendo().TreeList<TreeViewTest>()
        .Name("treelist")
        .Columns(columns =>
        {
            columns.Add().Field(e => e.ObjectName).Width(200);
            columns.Add().Field(e => e.ObjectId).Width(100);
            columns.Add().Field(e => e.ParentName).Width(200);
            columns.Add().Field(e => e.ParentId).Width(100);
        })
        .Filterable()
        .Sortable()
        .DataSource(dataSource => dataSource
            .Read(read => read.Action("GetTestTreeViewData", "Bom"))
            .ServerOperation(false)
            .Model(m =>
            {
                m.Id(f => f.ObjectId);
                m.ParentId(f => f.ParentId);
                m.Expanded(true);
                m.Field(f => f.ObjectName);
                m.Field(f => f.ParentName);

            })
        )
        .Height(540)
)

In DevTools I can see json object:

1. {Data: [{ObjectId: 1, ObjectName: "Object Name 1", ParentId: 0, ParentName: "Parent Name 0"},…],…}
1. AggregateResults: {}
2. Data: [{ObjectId: 1, ObjectName: "Object Name 1", ParentId: 0, ParentName: "Parent Name 0"},…]
1. 0: {ObjectId: 1, ObjectName: "Object Name 1", ParentId: 0, ParentName: "Parent Name 0"}
2. 1: {ObjectId: 2, ObjectName: "Object Name 2", ParentId: 1, ParentName: "Parent Name 1"}
3. 2: {ObjectId: 3, ObjectName: "Object Name 3", ParentId: 2, ParentName: "Parent Name 2"}
4. 3: {ObjectId: 4, ObjectName: "Object Name 4", ParentId: 3, ParentName: "Parent Name 3"}
5. 4: {ObjectId: 5, ObjectName: "Object Name 5", ParentId: 4, ParentName: "Parent Name 4"}
6. 5: {ObjectId: 6, ObjectName: "Object Name 6", ParentId: 5, ParentName: "Parent Name 5"}
7. 6: {ObjectId: 7, ObjectName: "Object Name 7", ParentId: 6, ParentName: "Parent Name 6"}
8. 7: {ObjectId: 8, ObjectName: "Object Name 8", ParentId: 7, ParentName: "Parent Name 7"}
9. 8: {ObjectId: 9, ObjectName: "Object Name 9", ParentId: 8, ParentName: "Parent Name 8"}
10. 9: {ObjectId: 10, ObjectName: "Object Name 10", ParentId: 9, ParentName: "Parent Name 9"}
3. Errors: null
4. Total: 10

 

but TreeView displays no data.

I ran a similar application in asp.net mvc
(the same view and the same controller)and it worked fine

Whatam I doing wrong ?

 

 

[Mihaela]

Hi Mariusz,

Thank you for sharing the complete TreeList configuration and screenshots. I greatly appreciate it.

I examined the screenshot with the JSON object returned from the server, and I noticed that the "ParentID" Model property is not nullable. By default, the ParentId field is nullable. Would you please set the Nullable() option to "false" in the Model configuration of the DataSource and let me know if the issue is resolved at your end?

        .DataSource(dataSource => dataSource
            .Read(read => read.Action("GetTestTreeViewData", "Bom"))
            .ServerOperation(false)
            .Model(m =>
            {
                m.Id(f => f.ObjectId);
                m.ParentId(f => f.ParentId).Nullable(false);
                m.Expanded(true);
                m.Field(f => f.ObjectName);
                m.Field(f => f.ParentName);

            })
        )

Regards, Mihaela Progress Telerik