Unplanned
Last Updated: 11 Aug 2020 17:20 by ADMIN
Scheduled for 2.17.0

The issue manifests both when

  • using .Add() or .Remove() on an ObservableCollection
  • creating a new List<T>(updatedData)

Happens in 2.14.1 first.

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

Planned
Last Updated: 07 Aug 2020 06:07 by ADMIN
Scheduled for 2.18.0
Created by: Rob
Comments: 1
Category: TreeView
Type: Feature Request
4

Add checkbox support at the node level.  Similar to...

 

https://www.telerik.com/kendo-angular-ui/components/treeview/checkboxes/

Unplanned
Last Updated: 09 Jul 2020 13:08 by ADMIN
If the treeview is in a component within the `@Body` and so gets disposed on navigation, there are errors in a WebAssembly app.
Need More Info
Last Updated: 28 Jun 2020 11:56 by ADMIN
Created by: Marin Bratanov
Comments: 4
Category: TreeView
Type: Feature Request
0

Hi everyone,

We created this item to request your feedback on how you use the treeview binding with regards to the Expanded state of the nodes.

At the moment, the treeview updates the field in the collection when an item gets expanded or collapsed, and that makes it unique in the suite - the other data bound components do not alter their data source silently, and this is the general pattern we want to follow in order to have consistency across the board.

Thus, there are several approaches we are considering and we want to get your take on how you would find this most comfortable:

  • Keep the current situation where the treeview updates the ExpandedField in the Data silently [we would rather change it] - the Data collection gets changed automatically. To control an expanded item, prepare the data source accordingly.
  • Use the OnExpand event to get the item and its new state in order to update the collection yourself if needed. If you don't use the field for anything but to control the state of the treeview, you will not need to change anything. To control an expanded item, prepare the data source accordingly when providing it to the treeview. If you will be reusing the same data source with alterations, you may have to handle the event to sync the state between the treeview and the data.
  • Use an ExpandedItems collection [we are inclined to go with this approach at the moment] - this will be a collection that you can provide to the treeview separately from its data source, like the selected items in a grid. This will let you avoid an Expanded field in the data (which we believe may not be present in an actual database anyway) and you will be able to use business logic to determine which items to add/remove to that collection, this also includes nested levels, even added through load-on-demand.
Completed
Last Updated: 27 Jun 2020 07:05 by ADMIN
Release 2.15.0
Created by: Erik
Comments: 2
Category: TreeView
Type: Feature Request
22

I need to be able to multiselect items in a treeview and drag n drop to reorder items.

(Same as RadTreeView AJAX component)

Completed
Last Updated: 16 Jun 2020 12:59 by ADMIN
Release 2.15.0
Created by: nonick
Comments: 4
Category: TreeView
Type: Feature Request
31

I would like a node click event exposed from the treeview.

At the moment, you need to use a template. Example and considerations are available in the following forum thread: https://www.telerik.com/forums/row-click-and-double-click-events#PQpO8DcbzkCArF3UqoLcWA.

Unplanned
Last Updated: 12 Jun 2020 11:19 by ADMIN
Created by: Erik
Comments: 7
Category: TreeView
Type: Feature Request
18
I need to be able to multiselect items in a treeview and drag n drop to reorder items.

(Same as RadTreeView AJAX component)
Completed
Last Updated: 29 May 2020 12:32 by ADMIN
Release 2.14.1
Unplanned
Last Updated: 18 May 2020 16:04 by ADMIN
Created by: Marcel
Comments: 5
Category: TreeView
Type: Bug Report
2

Hello,

I am trying to fill the TreeView using an async method. The first level is loaded an expanded. Subsequent levels are not. Or so it seams. They are loaded, but when expanding a node it expands and immediately collapses. Expanding a second time reveals the nodes loaded earlier.

I included a demo project. Open http://localhost:{port}/tree.

 

Best regards,

Marcel Gelijk

Unplanned
Last Updated: 12 May 2020 10:05 by ADMIN
Created by: Peter
Comments: 7
Category: TreeView
Type: Feature Request
3

Hi,

 

Is there a plan to support lines between treeview items as available in radtreeview?

 

radTreeView1.ShowLines = true; radTreeView1.LineStyle = TreeLineStyle.DashDot;

 

Without this it is very confusing to the end user what the connections between open items are.

 

Regards,


peter

 

 

 

 

Completed
Last Updated: 13 Mar 2020 11:40 by ADMIN
Release 2.7.0
Created by: Patrick
Comments: 6
Category: TreeView
Type: Feature Request
8

I have an extensive WPF background and so I naturally use ObservableCollection for virtually all UI type binding scenarios.

However I noticed that it seems the TreeView control doesn't seem to work when bound that way.
I switched the property to an array instead and it worked with no other modifications.

Duplicated
Last Updated: 02 Mar 2020 13:27 by ADMIN

Add the following Razor component and run. Click around tree, especially from disclosure icon to node to 'plus' icon. Error will occur.

 

=====================================

@page "/poopy"


@using Microsoft.AspNetCore.Components
@using Telerik.Blazor
@using Telerik.Blazor.Components
@using Telerik.Blazor.Components.Button

<style>
    .k-mid:hover .showme {
        display: block;
    }

    .showme {
        display: none;
        margin-left: 10px;
    }

    .showhim:hover .showme {
        display: block;
    }
</style>


@using Telerik.Blazor.Components.TreeView

<TelerikTreeView Data="@TreeData">
    <TelerikTreeViewBindings>
        <TelerikTreeViewBinding IdField="Id" ParentIdField="ParentIdValue" ExpandedField="Expanded" HasChildrenField="HasChildren">
            <ItemTemplate>
                <div @onclick="@(_ => NodeClicked((context as TreeItem).Text))" style="cursor: pointer">@((context as TreeItem).Text)</div>
                <div class="showme" @onclick="SayHelloHandler" style="cursor: pointer">
                    <TelerikIcon IconName="@IconName.Plus" />
                </div>
            </ItemTemplate>
        </TelerikTreeViewBinding>
    </TelerikTreeViewBindings>
</TelerikTreeView>

@helloString

@code {
    MarkupString helloString;

    void NodeClicked(string node)
    {
        helloString = new MarkupString(node);
    }


    void SayHelloHandler()
    {
        string msg = $"Hello from <strong>Telerik Blazor</strong> at {DateTime.Now}.<br /> Now you can use C# to write front-end!";
        helloString = new MarkupString(msg);
    }


    public class TreeItem
    {
        public int Id { get; set; }
        public string Text { get; set; }
        public int? ParentIdValue { get; set; }
        public bool HasChildren { get; set; }
        public bool Expanded { get; set; }
    }

    public IEnumerable<TreeItem> TreeData { get; set; }

    protected override void OnInitialized()
    {
        LoadTreeData();
    }

    private void LoadTreeData()
    {
        List<TreeItem> items = new List<TreeItem>();

        items.Add(new TreeItem()
        {
            Id = 1,
            Text = "Project",
            ParentIdValue = null,
            HasChildren = true,
            Expanded = true
        });

        items.Add(new TreeItem()
        {
            Id = 2,
            Text = "Design",
            ParentIdValue = 1,
            HasChildren = false,
            Expanded = true
        });
        items.Add(new TreeItem()
        {
            Id = 3,
            Text = "Implementation",
            ParentIdValue = 1,
            HasChildren = false,
            Expanded = true
        });

        TreeData = items;
    }
}

======================================

Microsoft.JSInterop.JSException

  HResult=0x80131500
  Message=Cannot read property 'scrollHeight' of null
TypeError: Cannot read property 'scrollHeight' of null
    at Object.r (https://localhost:44326/_content/telerik.ui.for.blazor.trial/js/telerik-blazor.js:1:1433)
    at https://localhost:44326/_framework/blazor.server.js:8:28347
    at new Promise (<anonymous>)
    at e.beginInvokeJSFromDotNet (https://localhost:44326/_framework/blazor.server.js:8:28316)
    at https://localhost:44326/_framework/blazor.server.js:1:19148
    at Array.forEach (<anonymous>)
    at e.invokeClientMethod (https://localhost:44326/_framework/blazor.server.js:1:19119)
    at e.processIncomingData (https://localhost:44326/_framework/blazor.server.js:1:17165)
    at e.connection.onreceive (https://localhost:44326/_framework/blazor.server.js:1:10276)
    at WebSocket.i.onmessage (https://localhost:44326/_framework/blazor.server.js:1:38027)
  Source=System.Private.CoreLib
  StackTrace:
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.JSInterop.JSRuntimeBase.<InvokeWithDefaultCancellation>d__13`1.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Telerik.Blazor.Components.TelerikAnimationContainerBase.<GetContentHeight>d__57.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Telerik.Blazor.Components.TelerikAnimationContainerBase.<SetMaxHeight>d__56.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__139_1(Object state)
   at System.Threading.QueueUserWorkItemCallback.<>c.<.cctor>b__6_0(QueueUserWorkItemCallback quwi)
   at System.Threading.ExecutionContext.RunForThreadPoolUnsafe[TState](ExecutionContext executionContext, Action`1 callback, TState& state)
   at System.Threading.QueueUserWorkItemCallback.Execute()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
Unplanned
Last Updated: 09 Jan 2020 20:27 by ADMIN

Repro plus workaround (already in):

<button @onclick="@SwitchDataSource">switch to other data source</button>

<TelerikTreeView Data="@FlatData">
    <TreeViewBindings>
        <TreeViewBinding IdField="Id" ParentIdField="ParentIdValue" ExpandedField="Expanded" TextField="Text" 
                         HasChildrenField="HasChildren" IconField="Icon">
            <ItemTemplate>
                @{
                    TreeItem currProduct = context as TreeItem;
                    @(currProduct.Text)
                }
            </ItemTemplate>
            </TreeViewBinding>
    </TreeViewBindings>
</TelerikTreeView>

@code {
    public class TreeItem
    {
        public int Id { get; set; }
        public string Text { get; set; }
        public int? ParentIdValue { get; set; }
        public bool HasChildren { get; set; }
        public string Icon { get; set; }
        public bool Expanded { get; set; }
    }

    async void SwitchDataSource()
    {
        //workaround - remove it to see the actual error
        foreach (TreeItem item in FlatData)
        {
            item.Expanded = false;
        }
        StateHasChanged();
        await Task.Delay(300);//awaits the animation that will hide the nodes we just collapsed so their elements get properly disposed
        
        //change data
        LoadSecondDataSource();
        //update UI
        StateHasChanged();
    }

    public IEnumerable<TreeItem> FlatData { get; set; }

    protected override void OnInitialized()
    {
        LoadFlatData();
    }

    private void LoadFlatData()
    {
        List<TreeItem> items = new List<TreeItem>();

        items.Add(new TreeItem()
        {
            Id = 1,
            Text = "Project",
            ParentIdValue = null,
            HasChildren = true,
            Icon = "folder",
            Expanded = true
        });

        items.Add(new TreeItem()
        {
            Id = 2,
            Text = "Design",
            ParentIdValue = 1,
            HasChildren = true,
            Icon = "brush",
            Expanded = true
        });
        items.Add(new TreeItem()
        {
            Id = 3,
            Text = "Implementation",
            ParentIdValue = 1,
            HasChildren = true,
            Icon = "folder",
            Expanded = true
        });

        items.Add(new TreeItem()
        {
            Id = 4,
            Text = "site.psd",
            ParentIdValue = 2,
            HasChildren = false,
            Icon = "psd",
            Expanded = true
        });
        items.Add(new TreeItem()
        {
            Id = 5,
            Text = "index.js",
            ParentIdValue = 3,
            HasChildren = false,
            Icon = "js"
        });
        items.Add(new TreeItem()
        {
            Id = 6,
            Text = "index.html",
            ParentIdValue = 3,
            HasChildren = false,
            Icon = "html"
        });
        items.Add(new TreeItem()
        {
            Id = 7,
            Text = "styles.css",
            ParentIdValue = 3,
            HasChildren = false,
            Icon = "css"
        });

        FlatData = items;
    }

    void LoadSecondDataSource()
    {
        List<TreeItem> items = new List<TreeItem>();

        items.Add(new TreeItem()
        {
            Id = 1,
            Text = "1",
            ParentIdValue = null,
            HasChildren = true
        });

        items.Add(new TreeItem()
        {
            Id = 2,
            Text = "1 1",
            ParentIdValue = 1,
            HasChildren = true
        });


        //if you add this, there is no error because the levels match
        //if the new data source does not have the same number of (maybe expanded) levels
        //you will get an error while disposing those levels
        //items.Add(new TreeItem()
        //{
        //    Id = 3,
        //    Text = "1 1 1",
        //    ParentIdValue = 2
        //});



        FlatData = items;
    }
}

Completed
Last Updated: 08 Jan 2020 14:20 by ADMIN
Release 2.6.0
Created by: Shadi
Comments: 0
Category: TreeView
Type: Bug Report
0
You cannot collapse (properly) an item whose children were loaded on demand. A second click changes the arrow direction, but does not collapse the child items, they only flicker a little. A few more clicks sometimes collapse the items but the arrow may keep being out of sync.
Completed
Last Updated: 23 Aug 2019 13:17 by ADMIN
Release 1.6.0
When you change the data source of the treeview and the new data has a different set of Expanded states than the old data, you will get a `Microsoft.JSInterop.JSException: 'Cannot read property 'scrollHeight' of null` in VS. It will also fail to show you proper debug information, symbols and source code.


Simple Repro

@using Telerik.Blazor.Components.TreeView
 
<button class="btn btn-primary" @onclick="@(() => ChangeTreeData(false))">Change tree data</button>
 
<TelerikTreeView Data="@FlatData">
    <TelerikTreeViewBindings>
        <TelerikTreeViewBinding ParentIdField="Parent" ExpandedField="IsExpanded"></TelerikTreeViewBinding>
    </TelerikTreeViewBindings>
</TelerikTreeView>
 
@code {
    public List<TreeItem> FlatData { get; set; } = new List<TreeItem>();
 
    public class TreeItem //most fields use the default names and will bind automatically in this example
    {
        public int Id { get; set; }
        public string Text { get; set; }
        public int? Parent { get; set; } //this is a non-default field name
        public bool HasChildren { get; set; }
        public bool IsExpanded { get; set; } //this is a non-default field name
    }
 
    protected override void OnInit()
    {
        ChangeTreeData(true);
    }
 
    int currIndex { get; set; } = 0;
 
    void ChangeTreeData(bool expandItems)
    {
        currIndex++;
 
        FlatData.Clear();
 
        List<TreeItem> data = new List<TreeItem>();
 
        data.Add(new TreeItem { Id = currIndex, HasChildren = true, IsExpanded = expandItems, Parent = null, Text = $"root {currIndex}" });
        data.Add(new TreeItem { Id = currIndex + 1, HasChildren = false, IsExpanded = expandItems, Parent = currIndex, Text = $"root {currIndex}: child one" });
 
        FlatData.AddRange(data);
    }
 
}
Completed
Last Updated: 23 Jul 2019 12:18 by ADMIN
Release 1.4.0
Created by: nonick
Comments: 0
Category: TreeView
Type: Bug Report
2

When using load-on-demand, you may not know how much data there is and how many levels deep it will go. You need the OnExpand event to fire for each node so you can call your services and retrieve data.

Unfortunately, it does not fire for the second level of nodes, so you cannot load data for them.