Last Updated: 05 Jun 2020 07:37 by ADMIN
Created on: 04 Jun 2020 22:58
Category: Grid
Type: Bug Report
Grid OnRead .Clear()

Grid OnRead .Clear() Issue

With the following component:

@page "/counter"
@using System.Collections.ObjectModel
General grid with its most common features
<TelerikGrid Data="@MyData" Pageable="true" @bind-Page="page" PageSize="5" TotalCount="30" OnRead="@ReadItems" >
        <GridColumn Field="@(nameof(SampleData.Id))" Width="120px" />
        <GridColumn Field="@(nameof(SampleData.Name))" Title="Employee Name" Groupable="false" />
        <GridColumn Field="@(nameof(SampleData.Team))" Title="Team" />
        <GridColumn Field="@(nameof(SampleData.HireDate))" Title="Hire Date" />

@code {
    public List<SampleData> MyData { get; set; } = new List<SampleData>();
    //public ObservableCollection<SampleData> MyData { get; set; } = new ObservableCollection<SampleData>();
    private int page = 1;

    private void ReadItems(GridReadEventArgs args)
        //MyData = new List<SampleData>();  //OK!
        //MyData = new ObservableCollection<SampleData>(); //OK!
        MyData.Clear();  //List: No update. ObservableCollection: System.StackOverflowException!

    private void Populate()
        foreach (var data in Enumerable.Range((page - 1) * 5, 5).Select(x => new SampleData
            Id = x,
            Name = "name " + x,
            Team = "team " + x % 5,
            HireDate = DateTime.Now.AddDays(-x).Date

    public class SampleData
        public int Id { get; set; }
        public string Name { get; set; }
        public string Team { get; set; }
        public DateTime HireDate { get; set; }

I see the issues in the comment fields.  Changing OnRead to async makes no difference.  

The workaround is to assign a new List or ObservableCollection instead of using .Clear()

1 comment
Marin Bratanov
Posted on: 05 Jun 2020 07:37

Hello Rob,

When an observable collection is .Clear()-ed, the grid monitors that and updates its data. Now that you have bound the OnRead event, it will fire. This will, in turn, update the collection again and so you get an infinite loop which causes the stack overflow. I will add this info to the docs (commit).


Marin Bratanov
Progress Telerik

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