我们有哪些选项可以从 ASP.NET Core Web Api 生成 PDF

Question

我需要从 HTML Canvas 生成 PDF，但该过程必须在作为 ASP.NET Core Web Api 的服务器端完成。

Answer 1

在服务器端，您可以HTML将视图输出为，string并且可以使用任何从 .pdf 生成 PDF 的库HTML string。要渲染视图，string请参阅此链接在 获得后在 .NET Core 中将视图返回为字符串HTML，您需要将其传递给库，请参阅此链接以在 .NET 中转换HTML为string 将 HTML 转换为 PDF

1 创建一个 C# 扩展方法将视图渲染为字符串

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewEngines;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using System.IO;
using System.Threading.Tasks;

namespace CC.Web.Helpers
{
    public static class ControllerExtensions
    {
        public static async Task<string> RenderViewAsync<TModel>(this Controller controller, string viewName, TModel model, bool partial = false)
        {
            if (string.IsNullOrEmpty(viewName))
            {
                viewName = controller.ControllerContext.ActionDescriptor.ActionName;
            }

            controller.ViewData.Model = model;

            using (var writer = new StringWriter())
            {
                IViewEngine viewEngine = controller.HttpContext.RequestServices.GetService(typeof(ICompositeViewEngine)) as ICompositeViewEngine;
                ViewEngineResult viewResult = viewEngine.FindView(controller.ControllerContext, viewName, !partial);

                if (viewResult.Success == false)
                {
                    return $"A view with the name {viewName} could not be found";
                }

                ViewContext viewContext = new ViewContext(
                controller.ControllerContext,
                viewResult.View,
                controller.ViewData,
                controller.TempData,
                writer,
                new HtmlHelperOptions()
            );

                await viewResult.View.RenderAsync(viewContext);

                return writer.GetStringBuilder().ToString();
            }
        }
    }
} 

2) 将视图渲染为字符串

viewHtml = await this.RenderViewAsync("Report", model);

3) 使用 HTML 创建 PDF

    Byte[] res = null;
    using (MemoryStream ms = new MemoryStream())
    {
        var pdf = TheArtOfDev.HtmlRenderer.PdfSharp.PdfGenerator.GeneratePdf(viewHtml, PdfSharp.PageSize.A4);
        pdf.Save(ms);
        res = ms.ToArray();
    }

Answer 2

using IronPdf;
IronPdf.HtmlToPdf Renderer = new IronPdf.HtmlToPdf();
// Render an HTML document or snippet as a string
Renderer.RenderHtmlAsPdf("<h1>Hello World</h1>").SaveAs("html-string.pdf");
// Advanced: 
// Set a "base url" or file path so that images, javascript and CSS can be loaded  
var PDF = Renderer.RenderHtmlAsPdf("<img src='icons/iron.png'>",@"C:\site\assets\");
PDF.SaveAs("html-with-assets.pdf");

适用于 .NET Core 的 IronPDF