Native Blazor Report Viewer Events Overview

The Native Blazor Report Viewer exposes events that will be emitted at various points in the report rendering process such as when the rendering begins, ends, etc.

OnRenderingBegin

Occurs before rendering the report. The event is triggered only on preview. The export operation has a dedicated event.

This event has one argument of type RenderingBeginEventArgs which represents the device information settings that will be used for the rendering of the report in the HTML5/HTML5Interactive format. Sample usage:

<ReportViewer @ref="reportViewer1"
    ServiceUrl="https://demos.telerik.com/reporting/api/reports"
    @bind-ReportSource="@ReportSource"
    ServiceType="@ReportViewerServiceType.REST"
    Height="800px"
    Width="100%"
    OnRenderingBegin="@RenderingBegin"></ReportViewer>

@code {
    ReportViewer reportViewer1;
    public ReportSourceOptions ReportSource { get; set; } = new ReportSourceOptions("Report Catalog.trdx", new Dictionary<string, object>{});

    void RenderingBegin(RenderingBeginEventArgs args)
    {
        // Enable search in the rendered document
        args.EnableSearch = true; //default value
    }
}

OnRenderingEnd

Occurs after the rendering of the report finishes. The event is triggered only on preview. The export operation has a dedicated event. This event has one argument of type RenderingEndEventArgs which represents the returned DocumentInfo entity at the end of the report rendering.

Sample usage:

<ReportViewer @ref="reportViewer1"
    ServiceUrl="https://demos.telerik.com/reporting/api/reports"
    @bind-ReportSource="@ReportSource"
    ServiceType="@ReportViewerServiceType.REST"
    Height="800px"
    Width="100%"
    OnRenderingEnd="@RenderingEnd"></ReportViewer>

@code {
    ReportViewer reportViewer1;
    public ReportSourceOptions ReportSource { get; set; } = new ReportSourceOptions("Report Catalog.trdx", new Dictionary<string, object>{});

    async Task RenderingEnd(RenderingEndEventArgs args)
    {
        // Display alert with the page count of the rendered report
        await JsRuntime.InvokeVoidAsync("alert", $"The total page count of rendered report is: {args.PageCount}");
    }
}

OnExportStart

Occurs before exporting the report. This event has one argument of type ExportStartEventArgs which is an object with the following properties:

• DeviceInfo - The device info that will be used for the export operation.
• Format - The document format of the exported report.
• IsCancelled - Prevents the default render and export operation. Default value: false.

Sample usage:

<ReportViewer @ref="reportViewer1"
    ServiceUrl="https://demos.telerik.com/reporting/api/reports"
    @bind-ReportSource="@ReportSource"
    ServiceType="@ReportViewerServiceType.REST"
    Height="800px"
    Width="100%"
    OnExportStart="@ExportStart"></ReportViewer>

@code {
    ReportViewer reportViewer1;
    public ReportSourceOptions ReportSource { get; set; } = new ReportSourceOptions("Report Catalog.trdx", new Dictionary<string, object>{});

    async Task ExportStart(ExportStartEventArgs args)
    {
        // Cancel CSV exporting
        if(args.Format == "CSV")
        {
            args.IsCancelled = true;
            await JsRuntime.InvokeVoidAsync("alert", $"Exporting the report in the {args.Format} format is disabled");
        }
    }
}

OnExportEnd

Occurs after exporting the report. This event has one argument of type ExportEndEventArgs which is an object with the following properties:

• Url - The url of the exported report as a resource.
• Format - The document format of the exported report.
• Handled - Prevents the default export operation. Default value: false.
• WindowOpenTarget - Changes the target attribute specifying where to open the browser window. Default value is self.

Sample usage:

<ReportViewer @ref="reportViewer1"
    ServiceUrl="https://demos.telerik.com/reporting/api/reports"
    @bind-ReportSource="@ReportSource"
    ServiceType="@ReportViewerServiceType.REST"
    Height="800px"
    Width="100%"
    OnExportEnd="@ExportEnd"></ReportViewer>

@code {
    ReportViewer reportViewer1;
    public ReportSourceOptions ReportSource { get; set; } = new ReportSourceOptions("Report Catalog.trdx", new Dictionary<string, object>{});

    void ExportEnd(ExportEndEventArgs args)
    {
        // Change the window's open target
        if(args.Format == "PDF")
        {
            args.WindowOpenTarget = "_blank";
        }
    }
}

See Also

• Blazor Basics: Blazor Event Callbacks
• ASP.NET Core Blazor event handling