ClientControlContentBuilderBase<TSettings, TImpl>.Nonce(String) Method

Specifies the nonce value.

Namespace: DevExpress.AspNetCore.Reporting

Assembly: DevExpress.AspNetCore.Reporting.v25.1.dll

NuGet Package: DevExpress.AspNetCore.Reporting

Declaration

C#

public TImpl Nonce(
    string nonce
)

VB.NET

Public Function Nonce(
    nonce As String
) As TImpl

Parameters

Name	Type	Description
nonce	String	A string that is the nonce value

Returns

Type	Description
TImpl	A builder instance that can be used to further configure the reporting component.

Remarks

The Nonce property enables you to implement a nonce-based Content Security Policy.

Examples

Document Viewer

This example demonstrates how to implement a nonce-based Content Security Policy (CSP) for an ASP.NET Core Application through an HTTP response header:

View Example

In the HomeController.cs file, generate the nonce value. The RandomNumberGenerator class is used to generate cryptographically strong random values. Add an HTTP header with the Content Security Policy with nonce for the script-src directive.

The following code snippet shows how to add a nonce-based CSP for the Document Viewer component:

using DevExpress.AspNetCore.Reporting.WebDocumentViewer;
using DevExpress.XtraReports.Web.WebDocumentViewer;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Security.Cryptography;
using System.Threading.Tasks;
//...
public async Task<IActionResult> Viewer(
    [FromServices] IWebDocumentViewerClientSideModelGenerator clientSideModelGenerator,
    [FromQuery] string reportName) {
    var nonceBytes = new byte[32];
    using var generator = RandomNumberGenerator.Create();
    generator.GetBytes(nonceBytes);
    var nonce = Convert.ToBase64String(nonceBytes);
    HttpContext.Response.Headers.Add("Content-Security-Policy",
                string.Format("script-src 'self' 'nonce-{0}';", nonce) +
                "img-src data: https: http:;" +
                "style-src 'self';" +
                "connect-src 'self';" +
                "worker-src 'self' blob:;" +
                "frame-src 'self' blob:;"
            );
    var reportToOpen = string.IsNullOrEmpty(reportName) ? "TestReport" : reportName;
    var model = new Models.ViewerModel {
        ViewerModelToBind = await clientSideModelGenerator.GetModelAsync(reportToOpen, WebDocumentViewerController.DefaultUri),
        Nonce = nonce
    };
    return View(model);
}
//...

The new nonce value is generated each time the page loads.

On the page, pass the nonce value to the Nonce method:

CSHTML

@*...*@
@{
    var viewerRender = Html.DevExpress().WebDocumentViewer("DocumentViewer")
        .Height(null)
        .Width(null)
        .Nonce(Model.Nonce)
        .CssClassName("my-reporting-component")
        .Bind(Model.ViewerModelToBind);
    @viewerRender.RenderHtml()
}

CSS

.my-reporting-component {
        height: 850px;
        width: 100%;
    }

Note

Set the Height and Width to null for the application to work properly. You can specify the required height and width in a CSS class.

Report Designer

This example implements a nonce-based Content Security Policy (CSP) for an ASP.NET Core Application through an HTTP response header:

View Example

In the HomeController.cs file, generate the nonce value. The RandomNumberGenerator class is used to generate cryptographically strong random values. Add an HTTP header with the Content Security Policy with nonce for the script-src directive.

The following code snippet adds a nonce-based CSP for the Report Designer component:

using DevExpress.XtraReports.Web.ReportDesigner;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Threading.Tasks;
//...
public async Task<IActionResult> Designer(
    [FromServices] IReportDesignerClientSideModelGenerator clientSideModelGenerator,
    [FromQuery] string reportName) {

    var nonceBytes = new byte[32];
    using var generator = RandomNumberGenerator.Create();
    generator.GetBytes(nonceBytes);
    var nonce = Convert.ToBase64String(nonceBytes);

    HttpContext.Response.Headers.Add("Content-Security-Policy",
                string.Format("script-src 'self' 'nonce-{0}';", nonce) +
                "img-src data: https: http:;" +
                "style-src 'self';" +
                "connect-src 'self';" +
                "worker-src 'self' blob:;" +
                "frame-src 'self' blob:;"
            );

    Models.ReportDesignerCustomModel model = new Models.ReportDesignerCustomModel();
    model.ReportDesignerModel = await CreateDefaultReportDesignerModel(clientSideModelGenerator, reportName, null);
    model.Nonce = nonce;
    return View(model);
}
//...

The new nonce value is generated each time the page loads.

On the page, pass the nonce value to the Report Designer’s Nonce method:

CSHTML

@{
    var designerRender = Html.DevExpress().ReportDesigner("reportDesigner")
        .Height(null)
        .Width(null)
        .Nonce(Model.Nonce)
        .CssClassName("my-reporting-component")
        .Bind(Model.ReportDesignerModel);
    @designerRender.RenderHtml()
}

CSS

.my-reporting-component {
        height: 850px;
        width: 100%;
    }

Note

Set the Height and Width properties to null for the application to work properly. You can specify the required height and width in a CSS class.