Components / Grid / Export

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Export Events

You can customize the files exported to Excel and CSV by using the OnBeforeExport and the OnAfterExport events exposed to the GridExcelExport and GridCsvExport tags.

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OnBeforeExport

The OnBeforeExport event fires after the user clicks the ExcelExport or CsvExport button and before the export process starts. You can use the event to configure the exported Grid columns or change the exported data. The event handler receives a GridBeforeExcelExportEventArgs and GridBeforeCsvExportEventArgs object, depending on the type of export, which provides the following properties:

For Excel Export

  • Columns - List<GridExcelExportColumn> - a collection of all exportable columns in the Grid. These are all visible GridColumn instances. You can customize the following attributes of the Grid column before exporting it into Excel:

    • Width - define the width of the column in pixels.
    • Title - define the column title to be shown in the Excel file header.
    • NumberFormat - provide an Excel-compatible number/date format
    • Field - set the data bound field of the column.

To export a hidden Grid column that has its Visible parameter set to false, you can manually define an instance of the GridExcelExportColumn in the handler for the OnBeforeExport event and add that column to the args.Columns collection.

  • Data - IEnumerable<object> - assign a custom collection of data to be exported to Excel, for example only the selected items in the Grid.

  • isCancelled - bool - cancel the OnBeforeExcel event by setting the isCancelled property to true.

Using the Grid OnBeforeExport with Excel export

@* This example shows the capabilities of the OnBeforeExport event when exporting the Grid to Excel. *@

@* Required by BuiltInNumberFormats in the OnExcelBeforeExport handler *@
@using Telerik.Documents.SpreadsheetStreaming

@* Required by GridExcelExportColumn in the OnExcelBeforeExport handler *@
@using Telerik.Blazor.Components.Grid

<TelerikGrid Data="@GridData" Pageable="true" Sortable="true"
             @bind-SelectedItems="@SelectedItems"
             SelectionMode="@GridSelectionMode.Multiple"
             Resizable="true" Reorderable="true"
             FilterMode="@GridFilterMode.FilterRow"
             Groupable="true">

    <GridToolBarTemplate>
        <GridCommandButton Command="ExcelExport" Icon="@SvgIcon.FileExcel">Export to Excel</GridCommandButton>
        <label class="k-checkbox-label"><TelerikCheckBox @bind-Value="@ExportAllPages" />Export All Pages</label>
        <label class="k-checkbox-label"><TelerikCheckBox @bind-Value="@ExportSelectedItemsOnly" />Export Selected Items Only</label>
    </GridToolBarTemplate>

    <GridExport>
        <GridExcelExport FileName="telerik-grid-export" AllPages="@ExportAllPages" OnBeforeExport="@OnExcelBeforeExport" />
    </GridExport>

    <GridColumns>
        <GridColumn Field="@nameof(SampleData.ProductId)" Title="ID" Width="100px" Visible="false" />
        <GridColumn Field="@nameof(SampleData.ProductName)" Title="Product Name" Width="300px" />
        <GridColumn Field="@nameof(SampleData.UnitsInStock)" Title="In stock" Width="100px" />
        <GridColumn Field="@nameof(SampleData.Price)" Title="Unit Price" Width="200px" />
        <GridColumn Field="@nameof(SampleData.Discontinued)" Title="Discontinued" Width="100px" />
        <GridColumn Field="@nameof(SampleData.ReleaseDate)" Title="Release Date" Width="300px" />
    </GridColumns>
</TelerikGrid>

@code {
    private List<SampleData> GridData { get; set; } = new();

    private IEnumerable<object> SelectedItems = Enumerable.Empty<object>();

    private bool ExportAllPages { get; set; }

    private bool ExportSelectedItemsOnly { get; set; } = true;

    private void OnExcelBeforeExport(GridBeforeExcelExportEventArgs args)
    {
        // Export the hidden ProductId column that has Visible="false"
        var exportableHiddenColumn = new GridExcelExportColumn()
        {
            Title = "Product Id",
            Field = nameof(SampleData.ProductId)
        };
        args.Columns.Insert(0, exportableHiddenColumn);

        // Customize the Width of the first exported column
        args.Columns[0].Width = "200px";

        // Change the format of the Price column
        // BuiltInNumberFormats is part of the Telerik.Documents.SpreadsheetStreaming namespace
        args.Columns[3].NumberFormat = BuiltInNumberFormats.GetCurrency2();

        // Change the format of the ReleaseDate column
        args.Columns[3].NumberFormat = BuiltInNumberFormats.GetShortDate();

        // Export only the first 4 columns in the Grid
        //args.Columns = (args.Columns.Take(4)).ToList();

        if (ExportSelectedItemsOnly)
        {
            // Export only the SelectedItems instead of the Grid data
            args.Data = SelectedItems;
        }

        // Set IsCancelled to true if you want to prevent exporting
        args.IsCancelled = false;
    }

    protected override void OnInitialized()
    {
        GridData = Enumerable.Range(1, 9).Select(x => new SampleData
        {
            ProductId = x,
            ProductName = $"Product {x}",
            UnitsInStock = x * 2,
            Price = 3.14159m * x,
            Discontinued = x % 4 == 0,
            ReleaseDate = DateTime.Now.AddDays(-x)
        }).ToList();

        SelectedItems = GridData.Take(5);
    }

    public class SampleData
    {
        public int ProductId { get; set; }
        public string ProductName { get; set; }
        public int UnitsInStock { get; set; }
        public decimal Price { get; set; }
        public bool Discontinued { get; set; }
        public DateTime ReleaseDate { get; set; }
    }
}

For CSV Export

  • Data - IEnumerable<object> - assign a custom collection of data to be exported to CSV, for example only the selected items in the Grid.

  • Columns - List<GridCsvExportColumn> - a collection of all exportable columns in the Grid. These are all visible GridColumn instances. You can customize the following attributes of the Grid column before exporting it into Excel:

    • Title - define the column title to be shown in the Excel file header.
    • Field - set the data bound field of the column.

To export a hidden Grid column that has its Visible parameter set to false, you can manually define an instance of the GridCsvExportColumn in the handler for the OnBeforeExport event and add that column to the args.Columns collection.

  • isCancelled - bool - you can cancel the OnBeforeExcel event by setting the isCancelled field to true.
@* This example showcases the capabilities of the OnBeforeExport event when exporting the Grid to CSV file. *@

@using Telerik.Documents.SpreadsheetStreaming

@*This using is for the GridCsvExportColumn in the OnExcelBeforeExport method*@
@using Telerik.Blazor.Components.Grid

<TelerikGrid Data="@GridData" Pageable="true" Sortable="true"
             @bind-SelectedItems="@SelectedItems"
             SelectionMode="@GridSelectionMode.Multiple"
             Resizable="true" Reorderable="true"
             FilterMode="@GridFilterMode.FilterRow" Groupable="true">

    <GridToolBarTemplate>
        <GridCommandButton Command="CsvExport" Icon="@SvgIcon.FileCsv">Export to CSV</GridCommandButton>
        <label class="k-checkbox-label"><TelerikCheckBox @bind-Value="@ExportAllPages" />Export All Pages</label>
    </GridToolBarTemplate>

    <GridExport>
        <GridCsvExport FileName="telerik-grid-export" AllPages="@ExportAllPages" OnBeforeExport="@OnBeforeCsvExport" />
    </GridExport>

    <GridColumns>
        <GridColumn Field="@nameof(SampleData.ProductId)" 
                    Title="ID"
                    Visible="false"
                    Width="100px" />
        <GridColumn Field="@nameof(SampleData.ProductName)" Title="Product Name" Width="300px" />
        <GridColumn Field="@nameof(SampleData.UnitsInStock)" Title="In stock" Width="100px" />
        <GridColumn Field="@nameof(SampleData.Price)" Title="Unit Price" Width="200px" />
        <GridColumn Field="@nameof(SampleData.Discontinued)" Title="Discontinued" Width="100px" />
        <GridColumn Field="@nameof(SampleData.FirstReleaseDate)" Title="Release Date" Width="300px" />
    </GridColumns>
</TelerikGrid>

@code {
    private async Task OnBeforeCsvExport(GridBeforeCsvExportEventArgs args)
    {
        //export the SelectedItems

        args.Data = SelectedItems;

        //export a hidden column (Visible set to false)

        var exportableHiddenColumn = new GridCsvExportColumn()
            {
                Title = "Id",
                Field = nameof(SampleData.ProductId)
            };

        args.Columns.Insert(0, exportableHiddenColumn);

        //set the IsCancelled flag to true if you want to cancel the OnBeforeExport event

        args.IsCancelled = false;
    }

    private IEnumerable<object> SelectedItems = Enumerable.Empty<object>();

    List<SampleData> GridData { get; set; }
    bool ExportAllPages { get; set; }

    protected override void OnInitialized()
    {
        GridData = Enumerable.Range(1, 100).Select(x => new SampleData
            {
                ProductId = x,
                ProductName = $"Product {x}",
                UnitsInStock = x * 2,
                Price = 3.14159m * x,
                Discontinued = x % 4 == 0,
                FirstReleaseDate = DateTime.Now.AddDays(-x)
            }).ToList();

        SelectedItems = GridData.Take(5);
    }

    public class SampleData
    {
        public int ProductId { get; set; }
        public string ProductName { get; set; }
        public int UnitsInStock { get; set; }
        public decimal Price { get; set; }
        public bool Discontinued { get; set; }
        public DateTime FirstReleaseDate { get; set; }
    }
}

OnAfterExport

The OnAfterExport event fires after OnBeforeExport and before the generated file is provided to the user. You can use the event to make changes to the exported file. The event handler receives a GridAfterExcelExportEventArgs or GridAfterCsvExportEventArgs object, depending on the type of export, which provides the following fields:

For Excel Export

  • Stream - MemoryStream - The output of the Excel export as a memory stream. The stream itself is finalized, so that the resource does not leak. To read and work with the stream, clone its available binary data to a new MemoryStream instance.
@* Get the output of the excel export as a memory stream *@

@using System.IO

<TelerikGrid Data="@GridData" Pageable="true" Sortable="true"
             @bind-SelectedItems="@SelectedItems"
             SelectionMode="@GridSelectionMode.Multiple"
             Resizable="true" Reorderable="true"
             FilterMode="@GridFilterMode.FilterRow" Groupable="true">

    <GridToolBarTemplate>
        <GridCommandButton Command="ExcelExport" Icon="@SvgIcon.FileExcel">Export to Excel</GridCommandButton>
        <label class="k-checkbox-label"><TelerikCheckBox @bind-Value="@ExportAllPages" />Export All Pages</label>
    </GridToolBarTemplate>

    <GridExport>
        <GridExcelExport FileName="telerik-grid-export"
                         AllPages="@ExportAllPages"
                         OnAfterExport="@OnExcelAfterExport" />
    </GridExport>

    <GridColumns>
        <GridColumn Field="@nameof(SampleData.ProductId)" Title="ID" Width="100px" />
        <GridColumn Field="@nameof(SampleData.ProductName)" Title="Product Name" Width="300px" />
        <GridColumn Field="@nameof(SampleData.UnitsInStock)" Title="In stock" Width="100px" />
        <GridColumn Field="@nameof(SampleData.Price)" Title="Unit Price" Width="200px" />
        <GridColumn Field="@nameof(SampleData.Discontinued)" Title="Discontinued" Width="100px" />
        <GridColumn Field="@nameof(SampleData.FirstReleaseDate)" Title="Release Date" Width="300px" />
    </GridColumns>
</TelerikGrid>

@code {
    private async Task OnExcelAfterExport(GridAfterExcelExportEventArgs args)
    {
        var bytes = args.Stream.ToArray();
        var excelStream = new MemoryStream(bytes);        
    }

    private MemoryStream excelStream { get; set; }

    private IEnumerable<object> SelectedItems = Enumerable.Empty<object>();

    List<SampleData> GridData { get; set; }
    bool ExportAllPages { get; set; }

    protected override void OnInitialized()
    {
        GridData = Enumerable.Range(1, 100).Select(x => new SampleData
            {
                ProductId = x,
                ProductName = $"Product {x}",
                UnitsInStock = x * 2,
                Price = 3.14159m * x,
                Discontinued = x % 4 == 0,
                FirstReleaseDate = DateTime.Now.AddDays(-x)
            }).ToList();
    }

    public class SampleData
    {
        public int ProductId { get; set; }
        public string ProductName { get; set; }
        public int UnitsInStock { get; set; }
        public decimal Price { get; set; }
        public bool Discontinued { get; set; }
        public DateTime FirstReleaseDate { get; set; }
    }
}

For CSV Export

  • Stream - MemoryStream - The output of the CSV export as a MemoryStream. The stream itself is finalized, so that the resource does not leak. To read and work with the stream, clone its available binary data to a new MemoryStream instance.
@* Get the output of the CSV export as a memory stream *@

@using System.IO

<TelerikGrid Data="@GridData" Pageable="true" Sortable="true"
             @bind-SelectedItems="@SelectedItems"
             SelectionMode="@GridSelectionMode.Multiple"
             Resizable="true" Reorderable="true"
             FilterMode="@GridFilterMode.FilterRow" Groupable="true">

    <GridToolBarTemplate>
        <GridCommandButton Command="CsvExport" Icon="@SvgIcon.FileCsv">Export to CSV</GridCommandButton>
        <label class="k-checkbox-label"><TelerikCheckBox @bind-Value="@ExportAllPages" />Export All Pages</label>
    </GridToolBarTemplate>

    <GridExport>
        <GridCsvExport FileName="telerik-grid-export"
                       AllPages="@ExportAllPages"
                       OnAfterExport="@OnCSVAfterExport" />
    </GridExport>

    <GridColumns>
        <GridColumn Field="@nameof(SampleData.ProductId)" Title="ID" Width="100px" />
        <GridColumn Field="@nameof(SampleData.ProductName)" Title="Product Name" Width="300px" />
        <GridColumn Field="@nameof(SampleData.UnitsInStock)" Title="In stock" Width="100px" />
        <GridColumn Field="@nameof(SampleData.Price)" Title="Unit Price" Width="200px" />
        <GridColumn Field="@nameof(SampleData.Discontinued)" Title="Discontinued" Width="100px" />
        <GridColumn Field="@nameof(SampleData.FirstReleaseDate)" Title="Release Date" Width="300px" />
    </GridColumns>
</TelerikGrid>

@code {
    private async Task OnCSVAfterExport(GridAfterCsvExportEventArgs args)
    {
        var bytes = args.Stream.ToArray();
        var excelStream = new MemoryStream(bytes);       
    }

    private MemoryStream csvStream { get; set; }

    private IEnumerable<object> SelectedItems = Enumerable.Empty<object>();

    List<SampleData> GridData { get; set; }
    bool ExportAllPages { get; set; }

    protected override void OnInitialized()
    {
        GridData = Enumerable.Range(1, 100).Select(x => new SampleData
            {
                ProductId = x,
                ProductName = $"Product {x}",
                UnitsInStock = x * 2,
                Price = 3.14159m * x,
                Discontinued = x % 4 == 0,
                FirstReleaseDate = DateTime.Now.AddDays(-x)
            }).ToList();
    }

    public class SampleData
    {
        public int ProductId { get; set; }
        public string ProductName { get; set; }
        public int UnitsInStock { get; set; }
        public decimal Price { get; set; }
        public bool Discontinued { get; set; }
        public DateTime FirstReleaseDate { get; set; }
    }
}

See Also

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