Export to pdf using ASP.NET 5

问题:

I am working on MVC 6 application(DNX Core 5.0 framework). Unfortunately, I don't find any library for pdf export.

Any help will be appreciated.

回答1:

If you must rely on Core you'll have two options:

1 - Wait a bit

Core is still RC1, slowly moving to RC2, and you won't find much libs really soon. Since .NET Core is taking much attention, first libs should come out in a few months, but I'd guess you'll have to wait for at least RC2 release.

2 - Fork (or similar)

You can grab an open-source project that best fits your needs, fork (if on GitHub) or just download and start updating to .NET Core. I've just done that with DapperExtensions and it's working like a charm. You can even add some spicy just for you ;)

---

On the other hand, if you just need something that works but with no direct need of embedding into .NET Core, I've managed to make JsReport work fine. It will start it's very own server (embedded server) based on Node but integration is really easy (with AspNet Core very own Dependecy Injection system!) and PDF are created with no further issue.

If that interests you, here are some instructions:

1 - References

Add those to your project.json:

"jsreport.Embedded": "0.8.1",
"jsreport.Client": "0.8.1"

2 - AspNet integration

After, follow instructions from jsReport here. You can configure AspNet DI system as here:

public void ConfigureServices(IServiceCollection services)
{
   // ...
   var _server = new EmbeddedReportingServer();
   _server.StartAsync().Wait();
   services.AddInstance<IEmbeddedReportingServer>(_server);
   services.AddSingleton<IReportingService>((s) => { return s.GetRequiredService<IEmbeddedReportingServer>().ReportingService; });
   // ...
}

To use you'll just have to either receive an IReportingService or manually grab it from Resolver on your controller, for instance.

3 - Usage

public IActionResult SomeReport()
{
   // This is <my> type of usage. It's a bit manual because I'm currently loading reports from DB. You can use it in a diferent way (check jsReport docs).
   var service = Resolver.GetRequiredService<jsreport.Client.IReportingService>();

   var phantomOptions = new jsreport.Client.Entities.Phantom()
   {
      format = "A4",
      orientation = "portrait",
      margin = "0cm"
   };
   phantomOptions.footer = "<h2>Some footer</h2>";
   phantomOptions.footerHeight = "50px";
   phantomOptions.header = "<h2>Some header</h2>";
   phantomOptions.headerHeight = "50px";
   var request = new jsreport.Client.RenderRequest()
   {
      template = new jsreport.Client.Entities.Template()
      {
         content = "<div>Some content for your report</div>",
         recipe = "phantom-pdf",
         name = "Your report name",
         phantom = phantomOptions
      }
   };

   var _report = service.RenderAsync(request).Result;

   // Request file download.
   return File(_report.Content, "application/pdf", "Some fancy name.pdf");
}

4 - Important: your server won't start (missing a zip file)

Due to changes from NuGet on AspNet projects, you have to manually move some content files which are not moved automatically.

First, find your dnx cache for the embedded server. Should be something like:
C:\Users\<name>\.dnx\packages\jsreport.Embedded\0.8.1.

You'll notice a folder called content there. Simply copy it's contents (two files: node.exe and jsreport-net-embedded.zip) into lib\net45.

So, to be plain simple and fool-proof: copy contents (files only) from
C:\Users\<name>\.dnx\packages\jsreport.Embedded\0.8.1\contents
into
C:\Users\<name>\.dnx\packages\jsreport.Embedded\0.8.1\lib\net45.

That should solve startup issues. Remember: first startup will extract files and should take a few minutes. After that, it will be much much faster.

回答2:

I finally figured out a way to generate pdf's from .NET Core (without any .NET framework dependencies) is using Node.js from within my .NET Core application. The following example shows how to implementing a HTML to PDF converter in a clean ASP.NET Core Web Application project (Web API template).

Install the NuGet package Microsoft.AspNetCore.NodeServices

In Startup.cs add the line services.AddNodeServices() like this

public void ConfigureServices(IServiceCollection services)
{
    // ... all your existing configuration is here ...

    // Enable Node Services
    services.AddNodeServices();
}

Now install the required Node.js packages:

From the command line change working directory to the root of the .NET Core project and run these commands.

npm init

and follow the instructions to create the package.json file

npm install jsreport-core --save
npm install jsreport-jsrender --save
npm install jsreport-phantom-pdf --save

Create a file pdf.js in the root of the project containing

module.exports = function (callback) {
    var jsreport = require('jsreport-core')();

    jsreport.init().then(function () {
        return jsreport.render({
            template: {
                content: '<h1>Hello {{:foo}}</h1>',
                engine: 'jsrender',
                recipe: 'phantom-pdf'
            },
            data: {
                foo: "world"
            }
        }).then(function (resp) {
            callback(/* error */ null, resp.content.toJSON().data);
        });
    }).catch(function (e) {
        callback(/* error */ e, null);
    })
};

Have a look here for more explanation on jsreport-core.

Now create an action in an Mvc controller that calls this Node.js script

[HttpGet]
public async Task<IActionResult> MyAction([FromServices] INodeServices nodeServices)
{
    var result = await nodeServices.InvokeAsync<byte[]>("./pdf");

    HttpContext.Response.ContentType = "application/pdf";

    string filename = @"report.pdf";
    HttpContext.Response.Headers.Add("x-filename", filename);
    HttpContext.Response.Headers.Add("Access-Control-Expose-Headers", "x-filename");
    HttpContext.Response.Body.Write(result, 0, result.Length);
    return new ContentResult();
}

Off course you can do whatever you want with the byte[] returned from nodeServices, in this example I'm just outputting it from a controller action so it can be viewed in the browser.

You could also exchange the data between Node.js and .NET Core by a base64 encoded string using resp.content.toString('base64') in pdf.js and use var result = await nodeServices.InvokeAsync<byte[]>("./pdf"); in the action and then decode the base64 encoded string.

---

Alternatives

Most pdf generator solutions still depend on .NET 4.5/4.6 framework. None of the two answers above (JsReport and RazorPDFCore) works for .NET Core yet.

There seems to be some paid alternatives available if you don't like to use Node.js:

• NReco.PdfGenerator.LT
• EVO HTML to PDF Converter Client for .NET Core
• Winnovative HTML to PDF Converter Client for .NET Core

I haven't tried any of these though.

I hope we will soon see some open source progress in this area.

回答3:

Necromancing.

Adding a dependency to NodeJS is subideal IMHO, especially considering .NET Core self-contained deployment.

As per 2017, you could use my port of PdfSharpCore to .NET Core 1.1
Resolves fonts, and it can use images. Comes with a nice sample application. You'll have to replace the DB part, however.

Credits go to:
https://github.com/groege/PdfSharpCore

which is a bit outdated, and doesn't contain a sample on how to use it with images.

Note that you need to register the font-resolver and the imageSource-Implementation before using the respective features:

PdfSharpCore.Fonts.GlobalFontSettings.FontResolver = new FontResolver();

MigraDocCore.DocumentObjectModel.MigraDoc.DocumentObjectModel
    .Shapes.ImageSource.ImageSourceImpl = 
          new PdfSharpCore.ImageSharp.ImageSharpImageSource();

回答4:

I know that this question was asked a while ago, and I know that there have been several answers provided already that may well be right for certain projects. But I recently created a GitHub repository that allows for the creation of PDFs directly from your C# code without any requirement for nodejs, javascript, or razor. The feature set is a bit limited at the moment but it generates PDFs with images (.jpg only at this stage), shapes, and formatted text. The library works with .net core 2.0 and has no dependency on any other PDF generation tool.

Please note that this is my own repository: https://github.com/GZidar/CorePDF

I do plan to add functionality over time but at least for now this may provide the basis for others to include simple PDF capability in their own projects without the need for additional tooling.

回答5:

I have amended the RazorAnt/RazorPDF which was working only for older MVC versions to work with ASP.NET Core. Its RazorPDFCore, available on nuget and github:

Example usage

class YourBaseController : RazorPDF.Controller {
    // [...]
    public IActionResult Pdf() {
        var model = /* any model you wish */
        return ViewPdf(model);
    }
}

In your Startup.cs

add the following line before services.AddMVc();

services.AddSingleton<PdfResultExecutor>();

PLEASE NOTE:

You need to inhere RazorPDF.Controller from your base controller before using the ViewPdf() method