Generating/Sending pdf email attachments within a hangfire job - asp.net-mvc

Question

In our ASP.NET MVC web application we send emails as part of scheduled tasks handled by Hangfire for which I am using Postal as described here
The method works fine and we are able to send HTML/text emails. Now we need to generate and attach PDF files as well. The attached PDF needs to be generated dynamically by use of a Razor template. First I tried to use Rotativa in order to generate the PDF. However I encountered the problem that method BuildPdf needs a ControllerContext which is not available in the background HangFire process. I tried to fake the ControllerContext as
using (var memWriter = new StringWriter(sb))
{
var fakeResponse = new HttpResponse(memWriter);
var fakeRequest = new HttpRequest(null, "http://wwww.oururl.com", null);
var fakeHttpContext = new HttpContext(fakeRequest, fakeResponse);
var emailController = new BackgroundEmailController();
var fakeControllerContext = new ControllerContext(new HttpContextWrapper(fakeHttpContext), new RouteData(), emailController);
var attachment = emailController.BillAttachment(email);
var pdf = attachment.BuildPdf(fakeControllerContext);
if (pdf != null && pdf.Count() > 0)
{
using (MemoryStream ms = new MemoryStream(pdf))
{
var contentType = new System.Net.Mime.ContentType(System.Net.Mime.MediaTypeNames.Application.Pdf);
email.Attach(new System.Net.Mail.Attachment(ms, contentType));
}
}
}
However this raised a NullReference error in Rotativa.
Then I tried first to compile the template view with RazorEngine to HTML(and then convert the HTML to pdf by some mean) as
var engineService = RazorEngineService.Create();
engineService.AddTemplate(cache_name, File.ReadAllText(billAttachmentTemplatePath));
engineService.Compile(cache_name, modelType: typeof(BillEmail));
var html = engineService.Run(cache_name, null, email);
using (var ms = CommonHelper.GenerateStreamFromString(html))
{
var contentType = new System.Net.Mime.ContentType(System.Net.Mime.MediaTypeNames.Text.Html);
email.Attach(new System.Net.Mail.Attachment(ms, contentType));
}
And it throws another NullReference in the RazorEngine dynamic DLL:
System.NullReferenceException: Object reference not set to an instance of an object.
at CompiledRazorTemplates.Dynamic.RazorEngine_bb2b366aaef64f2bbc2997353f88cc9e.Execute()
at RazorEngine.Templating.TemplateBase.RazorEngine.Templating.ITemplate.Run(ExecuteContext context, TextWriter reader)
I was wondering if anybody have suggestions for generating PDF files from a template in a Hangfire process?

Answer 1

If you are open to commercial solutions, you can try Telerik reporting and export it as pdf programmatically. You define your report and then invoke it to generate PDF on the server side, finally email the byte[] as email attachment. You can now kickoff this process using Hangfire job.
Here is a pseudo code assuming you have defined the structure of your report, Please look here for more details on how to create your report programatically.
public void GenerateAndEmailReport()
{
var reportSource = new InstanceReportSource();
Telerik.Reporting.Report report = new MyReport();
//populate data into report
reportSource.ReportDocument = report;
var reportProcessor = new ReportProcessor();
reportSource.ReportDocument = report;
var info = new Hashtable();
var result= reportProcessor.RenderReport("PDF", reportSource, info);
byte[]reportBytes = result.DocumentBytes;
SendEmail(reportBytes, "myreport.pdf"); // a method that takes the bytes and attach it to email.
}
Additional references from telerik.
send report as email
Generating PDF in console application
Saving a report programmatically