Unplanned
Last Updated: 19 Jul 2021 08:50 by ADMIN
I have a TreeList, bound to an ObservableCollection data source. When I try to add new children the component stays in Create mode even after I click on the Update button.
Unplanned
Last Updated: 11 Jul 2021 09:36 by ADMIN

Hello,

Here is your code of the example "how to load hierarchical data on demand" with the option FilterMode = "@ TreeListFilterMode.FilterMenu"
As you can see if we click on a node the whole hierarchy disappears. if you remove this option all work fine

 

@* this sample shows how to load hierarchical data on demand and one way of handling no data being returned. Depending on your models and data logic you may have to tweak some checks, review the code comments for details.

*@

<TelerikTreeList Data="@Data"
                 ItemsField="@(nameof(Employee.DirectReports))"
                 HasChildrenField="@(nameof(Employee.HasChildren))"
                 OnExpand="@OnExpandHandler"
                 Pageable="true" Width="550px" Height="400px" FilterMode="@TreeListFilterMode.FilterMenu" >
    <TreeListColumns>
        <TreeListColumn Field="Name" Expandable="true" Width="220px" />
        <TreeListColumn Field="HireDate" Width="120px" />
    </TreeListColumns>
</TelerikTreeList>

@code {
    public List<Employee> Data { get; set; }

    // load on demand through the event
    async Task OnExpandHandler(TreeListExpandEventArgs args)
    {
        Employee item = args.Item as Employee;
        if (item.HasChildren && // it is marked as having children
            (item.DirectReports == null || item.DirectReports.Count == 0) // there are no child items
            )
        {
            // request data
            var children = await GetChildren(item);

            if (children.Count > 0)
            {
                // child items exist - add them to the current item
                item.DirectReports = children;
            }
            else
            {
                // no nested data - hide the expand arrow
                item.HasChildren = false;
            }
        }
    }

    async Task<List<Employee>> GetChildren(Employee itm)
    {
        await Task.Delay(400); // simulate delay. Remove for a real app

        List<Employee> data = new List<Employee>();

        // to showcase an example of when no actual child items are returned
        // we will check for too long nesting chain with this simpe logic
        if (itm.Name.LastIndexOf("Child of") < 15)
        {
            data.Add(new Employee
            {
                Name = "Child of " + itm.Name,
                HasChildren = true
            });
        }

        return await Task.FromResult(data);
    }

    // sample model

    public class Employee
    {
        // hierarchical data collections
        public List<Employee> DirectReports { get; set; }
        public bool HasChildren { get; set; }

        // data fields for display
        public string Name { get; set; }
        public DateTime HireDate { get; set; }
    }

    // initial data generation

    protected override async Task OnInitializedAsync()
    {
        List<Employee> data = new List<Employee>();
        for (int i = 0; i < 6; i++)
        {
            data.Add(new Employee
            {
                Name = $"root: {i}",
                HireDate = DateTime.Now.AddYears(-i),
                HasChildren = true
            });
        }

        // mark an item as non-expandable (not having children)
        data[1].HasChildren = false;
        data[1].Name += "(not expandable) ";

        Data = data;
    }
}
Unplanned
Last Updated: 09 Jul 2021 14:26 by ADMIN
Created by: Leigh
Comments: 0
Category: TreeList
Type: Feature Request
1
Unlike the grid, you don't have an OnRowClick event that will overcome the async limitations you indicate in the docs and support for OnSelect. Since everything I have is async, the binding solution just doesn't do enough if I can't catch the click. Is there an alternative to OnRowClick for the TreeList? If not, why not?
Planned
Last Updated: 16 Jun 2021 14:12 by ADMIN
Created by: MaslovRG
Comments: 1
Category: TreeList
Type: Feature Request
1
It would be nice to have the same capabilities for working with TreeList columns as in the ColumnMenu for Grid. Espesially columns chooser. 
Unplanned
Last Updated: 04 May 2021 14:03 by ADMIN

The code below compiles and doesn't give any browser errors when run, but when you collapse a row, all data is collapsed and you can't expand it again.

If you change the line that generates the data to use a List instead of IEnumerable it will work as expected.

REPRODUCIBLE

<TelerikTreeList Data=Data
                 IdField="@nameof(Record.Id)"
                 ParentIdField="@nameof(Record.ParentId)"
                 Height="100%">
    <TreeListColumns>
        <TreeListCheckboxColumn CheckBoxOnlySelection="true" />
        <TreeListColumn Field="@nameof(Record.Text)" Title="" Expandable="true" />
        <TreeListColumn Field="@nameof(Record.Id)" Title="ID" />
        <TreeListColumn Field="@nameof(Record.ParentId)" Title="PARENT" />
    </TreeListColumns>
</TelerikTreeList>
@code {
    protected IEnumerable<Record> Data = new List<Record>();

    protected override void OnInitialized()
    {
        Data = Enumerable.Range(1, 10).Select(i => new Record(i));
    }

    public class Record
    {
        public Record(int i)
        {
            Id = i;
            if (i % 5 == 1)
                ParentId = null;
            else
                ParentId = (i - ((i - 1) % 5));
            Text = "Item " + i;
        }
        public long Id { get; set; }
        public long? ParentId { get; set; }
        public string Text { get; set; }
    }
} 

WORKAROUND

<TelerikTreeList Data=Data
                 IdField="@nameof(Record.Id)"
                 ParentIdField="@nameof(Record.ParentId)"
                 Height="100%">
    <TreeListColumns>
        <TreeListCheckboxColumn CheckBoxOnlySelection="true" />
        <TreeListColumn Field="@nameof(Record.Text)" Title="" Expandable="true" />
        <TreeListColumn Field="@nameof(Record.Id)" Title="ID" />
        <TreeListColumn Field="@nameof(Record.ParentId)" Title="PARENT" />
    </TreeListColumns>
</TelerikTreeList>
@code {
    protected List<Record> Data = new List<Record>();

    protected override void OnInitialized()
    {
        Data = Enumerable.Range(1, 10).Select(i => new Record(i)).ToList();
    }

    public class Record
    {
        public Record(int i)
        {
            Id = i;
            if (i % 5 == 1)
                ParentId = null;
            else
                ParentId = (i - ((i - 1) % 5));
            Text = "Item " + i;
        }
        public long Id { get; set; }
        public long? ParentId { get; set; }
        public string Text { get; set; }
    }
} 

 

Duplicated
Last Updated: 01 May 2021 10:08 by ADMIN
Created by: Andrzej
Comments: 4
Category: TreeList
Type: Feature Request
2

Please add TreeList Drag Drop Feature

Regards

Andrzej

---

ADMIN EDIT

This feature will arrive with the same feature for the grid in the 2.24.0 release in mid-May 2021.

---

Unplanned
Last Updated: 30 Apr 2021 12:42 by ADMIN
Created by: Renier Pretorius
Comments: 0
Category: TreeList
Type: Feature Request
1

Is it possible to specify different editor templates for different levels in hierarchical data?

What I am trying to do is to build a hierarchical structure for grouping items. The list of items is specified so, in the grouping hierarchy, I want to select an item as the child element of the lowest grouping level rather than typing the name of the item and resolving if it exists. I thus want for the lowest level, to have a combobox rather than an editbox. The data items presented in the treelist have a property to bind to.

---

ADMIN EDIT

If your models already have flags denoting their level, or otherwise denoting the special need for that particular model, you can use them in the editor template already.

---

Declined
Last Updated: 27 Apr 2021 12:13 by ADMIN

Issue - While restoring the tree list state from local storage any items that were expanded are not re-expanded

Repo - https://github.com/benhysell/BlazorGridPagingIssue

Example Inspired By - https://docs.telerik.com/blazor-ui/components/treelist/state#save-and-load-treelist-state-from-browser-localstorage

Steps to Reproduce

Expected behavior - Elements that had been expanded would be expanded again.

Details

Following the example https://docs.telerik.com/blazor-ui/components/treelist/state#save-and-load-treelist-state-from-browser-localstorage I copied the code into my application, however I wanted to save which items were expanded, so I commented out:

 state.ExpandedItems = null;

Looking at the resulting entries in local storage, it appears the ExpandedItems list is properly saved to local storage.

I added some logging to the OnStateInitHandler so I could see what was happening on load, my desired result was to ensure:

  • If there is nothing in local storage, collapse all items
  • If someone had stored some information in local storage use it

It appears everything is going out to local storage, and coming back in without issue, however the state of the expanded items is not reflected in the control.

 

Unplanned
Last Updated: 13 Apr 2021 06:35 by ADMIN
Created by: Stefan
Comments: 0
Category: TreeList
Type: Feature Request
1
I want to bind the treelist to dynamic objects like I can the grid: https://github.com/telerik/blazor-ui/tree/master/grid/binding-to-expando-object.
Unplanned
Last Updated: 22 Mar 2021 17:00 by ADMIN
Created by: Kasim
Comments: 0
Category: TreeList
Type: Feature Request
1

In the TreeList control of Blazor UI suite, I did not see any option to group header for columns. Column group header is an important feature and will certainly enhance the utility of the control multifold.

Below are few samples of column group headers:

 

VCL TreeList Control - High Performance DevExpress TreeView ListView Hybrid  Control for Delphi and C++Builder Developers

Header Bands | ASP.NET Web Forms Controls | DevExpress Documentation

Unplanned
Last Updated: 10 Feb 2021 13:24 by ADMIN
Created by: Andrzej
Comments: 0
Category: TreeList
Type: Feature Request
4

Please add TreeList Export to Excel

Regards

Andrzej

Duplicated
Last Updated: 08 Feb 2021 20:01 by ADMIN
At the moment, clicking a row always alters the selection. I want to use only the selection column for selection so row clicks don't change it. A key issue is that when SelectChildren is set to true it only works for the checkbox, so clicking the row removes the selected children, and I don't want that.
Completed
Last Updated: 29 Jan 2021 09:00 by ADMIN
Release 2.21.0
Created by: Jurgen
Comments: 6
Category: TreeList
Type: Feature Request
3
I now have a treelist with a few thousand items, but the filtering takes a few seconds, and halfway there is a refresh with partial results.

Now the users are complaining that they do not really know when the treelist is done with filtering.
Unplanned
Last Updated: 09 Dec 2020 11:37 by ADMIN
Created by: Jack
Comments: 3
Category: TreeList
Type: Feature Request
2
Need an OnRowDoubleClick event for editing purposes.
Completed
Last Updated: 01 Dec 2020 08:00 by ADMIN

If I pass XField parameters with a "null" value, it throws "ArgumentNullException: Value cannot be null. (Parameter 'name')" because it thinks the value is set, but apparently it does check if it's "null" before trying to "GetProperty".

 

Example, if any of these XField properties are null, it will throw the Exception

<TelerikTreeList Data="@Data"
                 IdField="@IdField"
                 ParentIdField="@ParentIdField"
                 HasChildrenField="@HasChildrenField"
                 ItemsField="@ItemsField">...</TelerikTreeList>

 

There should be a null check to ignore the use of that property in case it's null, otherwise, my code will need to be something like

 

@if (HasChildrenField != null && ItemsField != null)
{
    <TelerikTreeList Data="@Data"
                     IdField="@IdField"
                     ParentIdField="@ParentIdField"
                     HasChildrenField="@HasChildrenField"
                     ItemsField="@ItemsField">...</TelerikTreeList>
}
else if (HasChildrenField != null)
{
    <TelerikTreeList Data="@Data"
                     IdField="@IdField"
                     ParentIdField="@ParentIdField"
                     HasChildrenField="@HasChildrenField">...</TelerikTreeList>
}
else if (ItemsField != null)
{
    <TelerikTreeList Data="@Data"
                     IdField="@IdField"
                     ParentIdField="@ParentIdField"
                     ItemsField="@ItemsField">...</TelerikTreeList>
}

else

{

    <TelerikTreeList Data="@Data"
                     IdField="@IdField"
                     ParentIdField="@ParentIdField">...</TelerikTreeList>

}


Which isn't good.

 

At least "HasChildrenField" and "ItemsField" should have that check because it isn't a required parameter to have property for the TelerikTreeList  to work.

 

Error Stack

 

ArgumentNullException: Value cannot be null. (Parameter 'name')

  • System.Type.GetProperty(string name, BindingFlags bindingAttr)

  • System.Type.GetProperty(string name)

  • Telerik.Blazor.Extensions.ReflectionExtensions.GetPropertyValue(object target, string propertyName)

  • Telerik.Blazor.Data.TelerikTreeListDataSource<TItem>.CreateTreeListItem(TItem item, IEnumerable<TreeListItem<TItem>> childItems)

  • Telerik.Blazor.Data.TelerikTreeListDataSource<TItem>.GetItems(IEnumerable<TItem> data)

  • Telerik.Blazor.Data.TelerikTreeListDataSource<TItem>.BuildTree(IEnumerable<TItem> sourceData)

  • Telerik.Blazor.Data.TelerikTreeListDataSource<TItem>.InitData(IEnumerable<TItem> sourceData)

  • Telerik.Blazor.Data.TelerikTreeListDataSource<TItem>.ProcessData(IEnumerable data)

  • Telerik.Blazor.Components.Common.DataBoundComponent<TItem>.ProcessDataInternal()

  • Telerik.Blazor.Components.Common.DataBoundComponent<TItem>.OnParametersSetAsync()

  • Telerik.Blazor.Components.TelerikTreeList<TItem>.<>n__0()

  • Telerik.Blazor.Components.TelerikTreeList<TItem>.OnParametersSetAsync()

  • Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)

  • Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()

  • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)

  • Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToPendingTasks(Task task)

  • Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)

  • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewComponentFrame(ref DiffContext diffContext, int frameIndex)

  • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewSubtree(ref DiffContext diffContext, int frameIndex)

  • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InsertNewFrame(ref DiffContext diffContext, int newFrameIndex)

  • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(ref DiffContext diffContext, int oldStartIndex, int oldEndIndexExcl, int newStartIndex, int newEndIndexExcl)

  • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ComputeDiff(Renderer renderer, RenderBatchBuilder batchBuilder, int componentId, ArrayRange<RenderTreeFrame> oldTree, ArrayRange<RenderTreeFrame> newTree)

  • Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)

  • Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)

  • Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()

  • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)

  • Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()

  • Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessPendingRender()

  • Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToRenderQueue(int componentId, RenderFragment renderFragment)

  • Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged()

  • Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()

  • Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()

  • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)

  • Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToPendingTasks(Task task)

  • Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)

  • Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderRootComponentAsync(int componentId, ParameterView initialParameters)

  • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.CreateInitialRenderAsync(Type componentType, ParameterView initialParameters)

  • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.RenderComponentAsync(Type componentType, ParameterView initialParameters)

  • Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext+<>c__11<TResult>+<<InvokeAsync>b__11_0>d.MoveNext()

  • Microsoft.AspNetCore.Mvc.ViewFeatures.StaticComponentRenderer.PrerenderComponentAsync(ParameterView parameters, HttpContext httpContext, Type componentType)

  • Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.PrerenderedServerComponentAsync(HttpContext context, ServerComponentInvocationSequence invocationId, Type type, ParameterView parametersCollection)

  • Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.RenderComponentAsync(ViewContext viewContext, Type componentType, RenderMode renderMode, object parameters)

  • Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper.ProcessAsync(TagHelperContext context, TagHelperOutput output)

  • Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner.<RunAsync>g__Awaited|0_0(Task task, TagHelperExecutionContext executionContext, int i, int count)

Unplanned
Last Updated: 11 Nov 2020 16:03 by ADMIN
Created by: Andrea
Comments: 0
Category: TreeList
Type: Feature Request
3

I would like to have an event equivalent to the OnRead for the Grid so that I could make custom data operations such as applying custom filtering to the root items. 

---

ADMIN EDIT

In the meantime, loading data on demand only when a node expands can make database queries happen less often and return less data: https://docs.telerik.com/blazor-ui/components/treelist/data-binding/load-on-demand

---

Completed
Last Updated: 27 Oct 2020 06:32 by ADMIN
Release 2.18.0
Created by: Jurgen
Comments: 3
Category: TreeList
Type: Feature Request
6

I would like to start the tree grid with all rows collapsed. At the moment I can do this only through load on demand.

*** Thread created by admin on customer behalf ***

Declined
Last Updated: 20 Oct 2020 16:08 by ADMIN
Created by: Georgia N.
Comments: 3
Category: TreeList
Type: Bug Report
0

I use Guids to identify data in my application. It is a lot more reliable than using integers; however, it appears as if the TreeList does not support the use of Guids for the Id and ParentId fields when building the list's view.

---

ADMIN EDIT

This was not a bug, it was probably a configuration issue, as the scenario works, so this is marked as "declined". See the thread below for a sample.

---

Unplanned
Last Updated: 12 Oct 2020 07:35 by ADMIN
When I add a child to a node in the TreeList it would not render until I expand or collapse that node.
Unplanned
Last Updated: 06 Oct 2020 07:14 by ADMIN
Created by: SL
Comments: 0
Category: TreeList
Type: Feature Request
2
I want to show the totals in my hierarchical data
1 2