Asp.net 在 .NET Core 中以字符串形式返回视图

Thanks to Paris Polyzos and his article.

I'm re-posting his code here, just in case the original post got removed for any reason.

Create Service in file viewToString.cs as below code:

using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Abstractions;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Routing;
     
namespace WebApplication.Services
{
        public interface IViewRenderService
        {
            Task<string> RenderToStringAsync(string viewName, object model);
        }
     
        public class ViewRenderService : IViewRenderService
        {
            private readonly IRazorViewEngine _razorViewEngine;
            private readonly ITempDataProvider _tempDataProvider;
            private readonly IServiceProvider _serviceProvider;
     
            public ViewRenderService(IRazorViewEngine razorViewEngine,
                ITempDataProvider tempDataProvider,
                IServiceProvider serviceProvider)
            {
                _razorViewEngine = razorViewEngine;
                _tempDataProvider = tempDataProvider;
                _serviceProvider = serviceProvider;
            }
     
            public async Task<string> RenderToStringAsync(string viewName, object model)
            {
                var httpContext = new DefaultHttpContext { RequestServices = _serviceProvider };
                var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
     
                using (var sw = new StringWriter())
                {
                    var viewResult = _razorViewEngine.FindView(actionContext, viewName, false);
     
                    if (viewResult.View == null)
                    {
                        throw new ArgumentNullException($"{viewName} does not match any available view");
                    }
     
                    var viewDictionary = new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary())
                    {
                        Model = model
                    };
     
                    var viewContext = new ViewContext(
                        actionContext,
                        viewResult.View,
                        viewDictionary,
                        new TempDataDictionary(actionContext.HttpContext, _tempDataProvider),
                        sw,
                        new HtmlHelperOptions()
                    );
     
                    await viewResult.View.RenderAsync(viewContext);
                    return sw.ToString();
                }
            }
        }
}

2. Add the service to the Startup.cs file, as:

using WebApplication.Services;

public void ConfigureServices(IServiceCollection services)
{
    ...
    services.AddScoped<IViewRenderService, ViewRenderService>();
}

3. Add "preserveCompilationContext": true to the buildOptions in the project.json, so the file looks like:

{
    "version": "1.0.0-*",
    "buildOptions": {
    "debugType": "portable",
    "emitEntryPoint": true,
    "preserveCompilationContext": true
    },
    "dependencies": {
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.1",
    "Microsoft.AspNetCore.Mvc": "1.0.1"
    },
    "frameworks": {
    "netcoreapp1.0": {
        "dependencies": {
        "Microsoft.NETCore.App": {
            "type": "platform",
            "version": "1.0.1"
        }
        },
        "imports": "dnxcore50"
    }
    }
}

4. Define you model, for example:

public class InviteViewModel {
    public string   UserId {get; set;}
    public string   UserName {get; set;}
    public string   ReferralCode {get; set;}
    public int  Credits {get; set;}
}

5. Create your Invite.cshtml for example:

@{
    ViewData["Title"] = "Contact";
}
@ViewData["Title"].
user id: @Model.UserId

6. In the Controller:

a. Define the below at the beginning:

private readonly IViewRenderService _viewRenderService;

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

b. Call and return the view with model as below:

var result = await _viewRenderService.RenderToStringAsync("Email/Invite", viewModel);
return Content(result);

c. The FULL controller example, could be like:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using WebApplication.Services;

namespace WebApplication.Controllers
{
    [Route("render")]
    public class RenderController : Controller
    {
        private readonly IViewRenderService _viewRenderService;

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

    [Route("invite")]
    public async Task<IActionResult> RenderInviteView()
    {
        ViewData["Message"] = "Your application description page.";
        var viewModel = new InviteViewModel
        {
            UserId = "cdb86aea-e3d6-4fdd-9b7f-55e12b710f78",
            UserName = "Hasan",
            ReferralCode = "55e12b710f78",
            Credits = 10
        };
     
        var result = await _viewRenderService.RenderToStringAsync("Email/Invite", viewModel);
        return Content(result);
    }

    public class InviteViewModel {
        public string   UserId {get; set;}
        public string   UserName {get; set;}
        public string   ReferralCode {get; set;}
        public int  Credits {get; set;}
    } 
}