Grid Events

This article explains the events available in the Telerik Grid for Blazor. They are grouped logically.

CUD Events

The OnCreate, OnUpdate and OnDelete events let you get the data item that the user changed so you can transfer the user action to the actual data source.

The OnEdit and OnCancel events let you respond to user actions - when they want to edit an item and when the want to cancel changes on an item they have been editing. You can use them to, for example, prevent editing of certain items based on some condition.

You can read more about the CUD events in the Editing Overview article.

Read Event

In the common case, you provide all the data to the grid's Data collection and the grid performs operations like paging, filtering, sorting on it for you. In some cases you may want to do this with your own code (for example, to retrieve only a small number of items in order to improve the backend performance). You can do this by attaching to the OnRead event where you can perform all the data read operations in the grid. You can read more about them in the Manual Data Source Operations article.

Other Events

State Events

The grid state lets you control through code the aspects of the grid the user can control in the UI - such as filtering, sorting, grouping. The grid provides two events related to the state:

  • OnStateInit - fires when the grid initializes so you can provide a stored version of the grid.

  • OnStateChanged - fires when the user performs an action so you can see what area was changed and, if needed, alter the grid state.

Review the grid state article for more details and examples on how the grid state works and what you can do with it.

Command Button Click

The command buttons of a grid provide an OnClick event before firing their built-in command (such as opening a row for editing, or adding a new row). You can do this to implement some additional logic and to also handle custom commands - both from a Command Column, and from a Toolbar Button

SelectedItemsChanged

Fires when the item selection is enabled and the user changes the selected item or items.

OnRowClick

The OnRowClick event fires as a response to the user clicking on a row of the Grid. Clicking on the GridCommandButton, select row CheckBox, expanding a Detail Template or when the row is in edit/insert mode will not trigger the event.

The event handler receives a GridRowClickEventArgs object which provides the model of the clicked row in the Item field that you can cast to your model type.

The GridRowClickEventArgs class exposes an EventArgs property. It maps to MouseEventArgs or KeyboardEventArgs depending on the user's action (clicking the row with the mouse/tapping it on a touch device, or pressing Enter when the row is focused). You can use the event arguments to determine the keyboard key or the position of the mouse cursor when the user took an action.

The OnRowClick event fires before selection happens.

Use the OnRowClick event to load data on demand based on the clicked row

@* Use the OnRowClick event to load data on demand based on the clicked row *@

There is a deliberate delay in the data loading to showcase the async nature of the event

<TelerikGrid Data="@MyData"
             Height="400px"
             Width="700px"
             Pageable="true"
             OnRowClick="@OnRowClickHandler"
             SelectionMode="@GridSelectionMode.Single"
             @bind-SelectedItems="@SelectedItems">
    <GridColumns>
        <GridColumn Field="@(nameof(SampleData.Id))" Width="120px" />
        <GridColumn Field="@(nameof(SampleData.Name))" Title="Employee Name" />
        <GridColumn Field="@(nameof(SampleData.Team))" Title="Team" />
        <GridColumn Field="@(nameof(SampleData.HireDate))" Title="Hire Date" />
    </GridColumns>
</TelerikGrid>

@if (ProjectData.Any())
{
    <br />
    <TelerikGrid Data="@ProjectData" AutoGenerateColumns="true"
                 Pageable="true" PageSize="4" Width="700px">
    </TelerikGrid>
}

@code {
    // enable single row selection to showcase the clicked row to the user. Not mandatory
    public IEnumerable<SampleData> SelectedItems { get; set; } = Enumerable.Empty<SampleData>();

    // data that will be loaded on demand for the next components - another grid in this sample
    public List<ProjectModel> ProjectData { get; set; } = new List<ProjectModel>();

    async Task OnRowClickHandler(GridRowClickEventArgs args)
    {
        var model = args.Item as SampleData;

        ProjectData = await GetProjectData(model.Id);

        if (args.EventArgs is KeyboardEventArgs keyboardEventArgs)
        {
            Console.WriteLine($"The user clicked {keyboardEventArgs.Key} on row {model.Name}");
        }
        else if (args.EventArgs is MouseEventArgs mouseEventArgs)
        {
            Console.WriteLine($"The user clicked {mouseEventArgs.ClientX} {mouseEventArgs.ClientY} on row {model.Name}");
        }
    }

    async Task<List<ProjectModel>> GetProjectData(int id)
    {
        await Task.Delay(500); // simulate loading data from a service, remove from a real app

        ProjectData = new List<ProjectModel>()
        {
            new ProjectModel()
            {
                ProjectManagerId = id,
                ProjectName = $"Project name {id}",
                DueDate = DateTime.Today.AddDays(-id),
                isActive = id % 2 == 0 ? true : false
            }
        };
        return await Task.FromResult(ProjectData);
    }

    public IEnumerable<SampleData> MyData = Enumerable.Range(1, 30).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; }
    }

    public class ProjectModel
    {
        public int ProjectManagerId { get; set; }
        public string ProjectName { get; set; }
        public DateTime DueDate { get; set; }
        public bool isActive { get; set; }
    }
}

The result from the code snippet above

OnRowClick example

OnRowDoubleClick

The OnRowDoubleClick event fires as a response to the user double clicking on a row of the Grid. Clicking on the GridCommandButton, select row CheckBox, expanding a Detail Template or when the row is in edit/insert mode will not trigger the event.

The event handler receives a GridRowClickEventArgs object which provides the model of the clicked row in the Item field that you can cast to your model type.

The GridRowClickEventArgs class exposes an EventArgs property. It maps to MouseEventArgs or KeyboardEventArgs depending on the user's action (clicking the row with the mouse/tapping it on a touch device, or pressing Enter when the row is focused). You can use the event arguments to determine the keyboard key or the position of the mouse cursor when the user took an action.

The OnRowDoubleClick event fires before selection happens.

Use the OnRowDoubleClick event to receive information on the clicked row

@* Use the OnRowDoubleClick event to receive information on the row the user clicked on *@

<TelerikGrid Data="@MyData"
             Height="400px"
             Width="700px"
             Pageable="true"
             OnRowDoubleClick="@OnRowDoubleClickHandler">
    <GridColumns>
        <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" />
    </GridColumns>
</TelerikGrid>

@if (!String.IsNullOrEmpty(logger))
{
    <div>
        @logger
    </div>
}

@code {
    string logger = String.Empty;

    void OnRowDoubleClickHandler(GridRowClickEventArgs args)
    {
        var model = args.Item as SampleData;

        logger = $"Double clicked on {model.Name}";

        if (args.EventArgs is KeyboardEventArgs keyboardEventArgs)
        {
            Console.WriteLine($"The user clicked {keyboardEventArgs.Key} on row {model.Name}");
        }
        else if (args.EventArgs is MouseEventArgs mouseEventArgs)
        {
            Console.WriteLine($"The user clicked {mouseEventArgs.ClientX} {mouseEventArgs.ClientY} on row {model.Name}");
        }

    }

    public IEnumerable<SampleData> MyData = Enumerable.Range(1, 30).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; }
    }
}

OnRowContextMenu

The OnRowContextMenu event fires as a response to the user right clicking on a row of the Grid, the context menu keyboard button or long-touch for mobile devices. Clicking on the GridCommandButton, select row CheckBox, expanding a Detail Template or when the row is in edit/insert mode will not trigger the event.

The event handler receives a GridRowClickEventArgs object which provides the model of the clicked row in the Item field that you can cast to your model type.

The GridRowClickEventArgs class exposes an EventArgs property. It maps to MouseEventArgs or KeyboardEventArgs depending on the user's action (clicking the row with the mouse/tapping it on a touch device, or pressing Enter when the row is focused). You can use the event arguments to determine the keyboard key or the position of the mouse cursor when the user took an action.

The OnRowContextMenu is used to integrate the Context menu to the Grid Row.

Use the OnRowContextMenu event and get the data model

@* Get the row model from a context menu action (right click/long tap) *@

<TelerikGrid Data="@MyData"
             Pageable="true"
             PageSize="6"
             OnRowContextMenu="@OnRowContextMenuHandler">
    <GridColumns>
        <GridColumn Field="@(nameof(SampleData.Id))" Width="120px" />
        <GridColumn Field="@(nameof(SampleData.Name))" Title="Employee Name" />
        <GridColumn Field="@(nameof(SampleData.Team))" Title="Team" />
        <GridColumn Field="@(nameof(SampleData.HireDate))" Title="Hire Date" />
    </GridColumns>
</TelerikGrid>

<br />

@logger

@code {
    void OnRowContextMenuHandler(GridRowClickEventArgs args)
    {
        SampleData model = args.Item as SampleData;

        logger = $"OnRowContextMenu event fired from right clicking on {model.Name}";

        if (args.EventArgs is KeyboardEventArgs keyboardEventArgs)
        {
            Console.WriteLine($"The user clicked {keyboardEventArgs.Key} on row {model.Name}");
        }
        else if (args.EventArgs is MouseEventArgs mouseEventArgs)
        {
            Console.WriteLine($"The user clicked {mouseEventArgs.ClientX} {mouseEventArgs.ClientY} on row {model.Name}");
        }
    }

    public IEnumerable<SampleData> MyData = Enumerable.Range(1, 30).Select(x => new SampleData
    {
        Id = x,
        Name = "name " + x,
        Team = "team " + x % 5,
        HireDate = DateTime.Now.AddDays(-x).Date
    });

    public string logger { get; set; } = String.Empty;


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

OnRowExpand

The OnRowExpand event fires as a response to the user expanding the DetailTemplate of the Grid.

The event handler receives a GridRowExpandEventArgs object which provides the model of the clicked row in the Item field that you can cast to your model type.

Use the OnRowExpand event to load detailed data on demand. Another approach can be found on our public github repository.

@* Load data on demand for the expanded detail row.  *@

<TelerikGrid Data="salesTeamMembers"
             OnRowExpand="@OnRowExpandHandler">
    <DetailTemplate>
        @{
            var employee = context as MainModel;
            <TelerikGrid Data="employee.Orders" Pageable="true" PageSize="5">
                <GridColumns>
                    <GridColumn Field="OrderId"></GridColumn>
                    <GridColumn Field="DealSize"></GridColumn>
                </GridColumns>
            </TelerikGrid>
        }
    </DetailTemplate>
    <GridColumns>
        <GridColumn Field="Id"></GridColumn>
        <GridColumn Field="Name"></GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    async Task OnRowExpandHandler(GridRowExpandEventArgs args)
    {
        MainModel item = args.Item as MainModel;

        if(item.Orders == null)
        {
            item.Orders = await GenerateOrdersData(item.Id);
        }
    }

    async Task<List<DetailsModel>> GenerateOrdersData(int id)
    {
        var data = new List<DetailsModel>()
        {
            new DetailsModel()
            {
                OrderId = id,
                DealSize = id * 1234,
            }
        };

        return await Task.FromResult(data);
    }

    List<MainModel> salesTeamMembers { get; set; }

    protected override void OnInitialized()
    {
        salesTeamMembers = GenerateData();
    }

    private List<MainModel> GenerateData()
    {
        List<MainModel> data = new List<MainModel>();
        for (int i = 1; i <= 5; i++)
        {
            MainModel mdl = new MainModel { Id = i, Name = $"Name {i}" };
            data.Add(mdl);
        }
        return data;
    }

    public class MainModel
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<DetailsModel> Orders { get; set; }
    }

    public class DetailsModel
    {
        public int OrderId { get; set; }
        public double DealSize { get; set; }
    }
}

OnRowCollapse

The OnRowCollapse event fires as a response to the user collapsing the DetailTemplate of the Grid.

The event handler receives a GridRowCollapseEventArgs object which provides the model of the clicked row in the Item field that you can cast to your model type.

Use the OnRowCollapse event to get the Id of the collapsed row from the data model

@* Get the Id of the collapsed row *@

<TelerikGrid Data="salesTeamMembers"
             OnRowCollapse="@OnRowCollapseHandler">
    <DetailTemplate>
        @{
            var employee = context as MainModel;
            <TelerikGrid Data="employee.Orders" Pageable="true" PageSize="5">
                <GridColumns>
                    <GridColumn Field="OrderId"></GridColumn>
                    <GridColumn Field="DealSize"></GridColumn>
                </GridColumns>
            </TelerikGrid>
        }
    </DetailTemplate>
    <GridColumns>
        <GridColumn Field="Id"></GridColumn>
        <GridColumn Field="Name"></GridColumn>
    </GridColumns>
</TelerikGrid>

<br />

@logger

@code {
    void OnRowCollapseHandler(GridRowCollapseEventArgs args)
    {
        MainModel item = args.Item as MainModel;
        logger = $"The collapsed row is with id: {item.Id}";
    }

    public string logger { get; set; } = String.Empty;
    List<MainModel> salesTeamMembers { get; set; }

    protected override void OnInitialized()
    {
        salesTeamMembers = GenerateData();
    }

    private List<MainModel> GenerateData()
    {
        List<MainModel> data = new List<MainModel>();
        for (int i = 0; i < 5; i++)
        {
            MainModel mdl = new MainModel { Id = i, Name = $"Name {i}" };
            mdl.Orders = Enumerable.Range(1, 15).Select(x => new DetailsModel { OrderId = x, DealSize = x ^ i }).ToList();
            data.Add(mdl);
        }
        return data;
    }

    public class MainModel
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<DetailsModel> Orders { get; set; }
    }

    public class DetailsModel
    {
        public int OrderId { get; set; }
        public double DealSize { get; set; }
    }
}

OnRowRender

This event fires upon the rendering of the Grid rows. It receives an argument of type GridRowRenderEventArgs which exposes the following fields:

  • Item - an object you can cast to your model class to obtain the current data item.
  • Class - the CSS class that will be applied to the cells. The CSS rules that are set for that class will be visibly rendered on the Grid row.

Use the OnRowRender event to apply custom format to Grid rows based on certain condition

@* Conditional styling/formatting for a row *@

<style>
    .myCustomRowFormatting {
        background-color: blue;
        color: white;
        font-size: 10px;
        font-weight: bold;
    }
</style>

<TelerikGrid Data="@MyData" 
             Height="400px"
             Pageable="true"
             Width="750px"
             OnRowRender="@OnRowRenderHandler">
    <GridColumns>
        <GridColumn Field="@(nameof(SampleData.Id))" Width="120px" />
        <GridColumn Field="@(nameof(SampleData.Name))" Title="Employee Name" />
        <GridColumn Field="@(nameof(SampleData.Team))" Title="Team" />
        <GridColumn Field="@(nameof(SampleData.HireDate))" Title="Hire Date" />
    </GridColumns>
</TelerikGrid>

@code {
    void OnRowRenderHandler(GridRowRenderEventArgs args)
    {
        var item = args.Item as SampleData;

        if (item.Name.Contains("5"))
        {
            args.Class = "myCustomRowFormatting";
        }
    }

    public IEnumerable<SampleData> MyData = Enumerable.Range(1, 30).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; }
    }
}

PageChanged

The event fires when the user pages the grid.

Handle the PageChanged event to know when the user changes the page

@result

<TelerikGrid Data="@MyData" Pageable="true" PageSize="30"
    PageChanged="@PageChangedHandler" Height="300px">
    <GridColumns>
        <GridColumn Field="ID"></GridColumn>
        <GridColumn Field="TheName" Title="Employee Name"></GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    string result { get; set; }
    async Task PageChangedHandler(int currPage)
    {
        result = $"the user is now on page {currPage}. Note - the indexes are 1-based, not 0-based";
    }

    public IEnumerable<object> MyData = Enumerable.Range(1, 150).Select(x => new { ID = x, TheName = "name " + x });
}

One-way binding of the Page parameter should be used with the PageChanged event to keep the view-model in sync

@* Set initial page index, and keep it updated with the grid state to prevent it from resetting the grid page index on re-renders *@

<TelerikGrid Data="@MyData" Pageable="true" PageSize="30" Height="300px"
             PageChanged="@PageChangedHandler" Page="@PageIndex">
    <GridColumns>
        <GridColumn Field="ID"></GridColumn>
        <GridColumn Field="TheName" Title="Employee Name"></GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    int PageIndex { get; set; } = 2;
    async Task PageChangedHandler(int currPage)
    {
        PageIndex = currPage;
        // when using one-way binding for the Page parametr, make sure to update it in the PageChanged event
    }

    public IEnumerable<object> MyData = Enumerable.Range(1, 150).Select(x => new { ID = x, TheName = "name " + x });
}

See Also

In this article
Not finding the help you need? Improve this article