Click or drag to resize
Pdf Library for .NET

Current WebPage to Pdf in Asp.Net

A web application often needs to convert the page the user is looking at to pdf with a click of a button, taking into account the values the user has just entered into that page (a filled in form, for example).

Converting the page url with ConvertUrl(String) does not do this: the converter fetches the url as a new, anonymous request, so it gets a fresh copy of the page without the user's input (and without their session). The technique is to let the application render its own page to html - with the current values in it - and then convert that html string with ConvertHtmlString(String, String).

Important note  Important

The second parameter of ConvertHtmlString(String, String) is the base url the engine resolves the captured page's relative resources against - stylesheets, images, fonts. It must be the application's http origin including the path base and a trailing slash, not a file system path. A file system path loads no stylesheets and produces an unstyled pdf.

ASP.NET Core (Razor Pages)

The page model renders its own page to a string and hands that string to the converter. Rendering a Razor page to a string is done with the Razor view engine; the complete, reusable service that does it (ViewRenderService.cs) ships with the SelectPdf samples, alongside the CurrentWebPageToPdf page that uses it.

C#
Copy
public class CurrentWebPageToPdfModel : PageModel
{
    private readonly IViewRenderService _viewRenderService;

    public CurrentWebPageToPdfModel(IViewRenderService viewRenderService)
    {
        _viewRenderService = viewRenderService;
    }

    // the values the user typed into the page - they are posted back,
    // so they are still set when the page is rendered again below
    [BindProperty]
    public string TxtSampleText { get; set; }

    [BindProperty]
    public bool ChkSampleCheckbox { get; set; }

    public void OnGet()
    {
        TxtSampleText = "sample text";
        ChkSampleCheckbox = true;
    }

    public async Task<IActionResult> OnPost()
    {
        // render THIS page to a html string, with the posted values in it
        string htmlString = await _viewRenderService.RenderToStringAsync(
            "CurrentWebPageToPdf",
            "~/Pages/_Layout.cshtml",
            new CurrentWebPageToPdfModel(_viewRenderService)
            {
                TxtSampleText = this.TxtSampleText,
                ChkSampleCheckbox = this.ChkSampleCheckbox,
            });

        // the http origin the engine resolves the page's relative
        // stylesheets, images and fonts against
        string baseUrl = $"{Request.Scheme}://{Request.Host}{Request.PathBase}/";

        // instantiate a html to pdf converter object
        HtmlToPdf converter = new HtmlToPdf();

        // create a new pdf document converting the html string of the page
        PdfDocument doc = converter.ConvertHtmlString(htmlString, baseUrl);

        // save pdf document
        byte[] pdf = doc.Save();

        // close pdf document
        doc.Close();

        // return resulted pdf document
        FileResult fileResult = new FileContentResult(pdf, "application/pdf");
        fileResult.FileDownloadName = "Document.pdf";
        return fileResult;
    }
}
Converting the captured html

The conversion step itself is the same whatever produced the html string and whatever framework the application uses - so an application that already has the rendered html of a page (from a view engine, a template engine, or its own string building) only needs the following:

Copy
// instantiate a html to pdf converter object
HtmlToPdf converter = new HtmlToPdf();

// create a new pdf document converting the html string of the page
// (baseUrl resolves the relative resources referenced by that html)
PdfDocument doc = converter.ConvertHtmlString(htmlString, baseUrl);

// save pdf document
doc.Save("Sample.pdf");

// close pdf document
doc.Close();
See Also