在.NET Core中将视图返回为字符串-Java 学习之路

我发现了一些文章如何在ASP.NET中将视图返回到字符串，但无法转换为能够使用.NET Core运行它

public static string RenderViewToString(this Controller controller, string viewName, object model)
{
    var context = controller.ControllerContext;
    if (string.IsNullOrEmpty(viewName))
        viewName = context.RouteData.GetRequiredString("action");

    var viewData = new ViewDataDictionary(model);

    using (var sw = new StringWriter())
    {
        var viewResult = ViewEngines.Engines.FindPartialView(context, viewName);
        var viewContext = new ViewContext(context, viewResult.View, viewData, new TempDataDictionary(), sw);
        viewResult.View.Render(viewContext, sw);

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

假设能够使用以下控制器从控制器调用：

var strView = this.RenderViewToString("YourViewName", yourModel);

当我尝试将上述内容运行到.NET Core时，我遇到了很多编译错误 .

我试图将其转换为与.NET Core一起使用，但是失败了，任何人都可以帮助提及 using .. 所需的 using .. 和所需的 "dependencies": { "Microsoft.AspNetCore.Mvc": "1.1.0", ... }, .

一些其他示例代码是here和here和here

NOTE 我需要解决方案将视图转换为.NET Core中的 string ，无论转换的代码是什么，或者是另一种方法 .

7 回答

1

微软在https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/testing上有一篇关于控制器测试的优秀文章

返回ViewResult后，您可以获取字符串内容

var strResult = ViewResult.Content

回复于 2024-04-28T14:13:11+08:00

感谢Paris Polyzos和他的article .

我在这里重新发布他的代码，以防原始帖子因任何原因被删除 .

在文件 viewToString.cs 中创建 Service ，如下代码：

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();
            }
        }
    }
}

将服务添加到 Startup.cs 文件中，如下所示：

using WebApplication.Services;

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

将 "preserveCompilationContext": true 添加到 project.json 中的 buildOptions ，因此该文件如下所示：

{
  "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"
    }
  }
}

定义你 model ，例如：

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

创建 Invite.cshtml 例如：

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

在 Controller 中：

一个 . 在开头定义以下内容：

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

湾使用模型调用并返回视图，如下所示：

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

C . FULL控制器示例可能如下：

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;}
} 
}

回复于 2024-04-28T14:13:11+08:00

如果像我一样你有许多需要这个的控制器，比如报告网站，重复这个代码并不是很理想，甚至注入或调用另一个服务似乎并不合适 .

所以我已经制作了我自己的上述版本，但有以下不同之处：

模型强类型
查找视图时
错误检查
将视图呈现为部分或页面的能力
asynchronus
实现为控制器扩展
不需要DI

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();
            }
        }
    }
}

然后执行：

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

或者这对于PartialView：

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

回复于 2024-04-28T14:13:11+08:00

-1

上面的答案很好，但需要调整以使任何标记助手工作（我们需要使用实际的http上下文） . 此外，您还需要在视图中显式设置布局以获取呈现的布局 .

public class ViewRenderService : IViewRenderService
{
    private readonly IRazorViewEngine _razorViewEngine;
    private readonly ITempDataProvider _tempDataProvider;
    private readonly IServiceProvider _serviceProvider;
    private readonly IHostingEnvironment _env;
    private readonly HttpContext _http;

    public ViewRenderService(IRazorViewEngine razorViewEngine, ITempDataProvider tempDataProvider, IServiceProvider serviceProvider, IHostingEnvironment env, IHttpContextAccessor ctx)
    {
        _razorViewEngine = razorViewEngine; _tempDataProvider = tempDataProvider; _serviceProvider = serviceProvider; _env = env; _http = ctx.HttpContext;
    }

    public async Task<string> RenderToStringAsync(string viewName, object model)
    {
        var actionContext = new ActionContext(_http, new RouteData(), new ActionDescriptor());

        using (var sw = new StringWriter())
        {
            var viewResult = _razorViewEngine.FindView(actionContext, viewName, false);
            //var viewResult = _razorViewEngine.GetView(_env.WebRootPath, viewName, false); // For views outside the usual Views folder
            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(_http, _tempDataProvider), sw, new HtmlHelperOptions());
            viewContext.RouteData = _http.GetRouteData();
            await viewResult.View.RenderAsync(viewContext);
            return sw.ToString();
        }
    }
}

回复于 2024-04-28T14:13:11+08:00

2
我尝试了在@ Dotan Core 2.1中由@Hasan A Yousef回答的解决方案，但是csthml对我不起作用 . 它总是抛出NullReferenceException，见截图 .

为了解决这个问题，我将Html.ViewData.Model分配给一个新对象 . 这是我的代码 .
```
@page
@model InviteViewModel 
@{
    var inviteViewModel = Html.ViewData.Model;
}

<p>
    <strong>User Id:</strong> <code>@inviteViewModel.UserId </code>
</p>
```
回复于 2024-04-28T14:13:11+08:00

下面的链接解决了几乎相同的问题：

Where are the ControllerContext and ViewEngines properties in MVC 6 Controller?

在Hasan A Yousef的回答中，我必须进行与上面链接相同的更改，以使其适用于我：

using Microsoft.AspNetCore.Hosting;
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;
using System;
using System.IO;
using System.Threading.Tasks;

public class ViewRenderService : IViewRenderService
{
    private readonly IRazorViewEngine _razorViewEngine;
    private readonly ITempDataProvider _tempDataProvider;
    private readonly IServiceProvider _serviceProvider;
    private readonly IHostingEnvironment _env;

    public ViewRenderService(IRazorViewEngine razorViewEngine, ITempDataProvider tempDataProvider, IServiceProvider serviceProvider, IHostingEnvironment env)
    {
        _razorViewEngine = razorViewEngine; _tempDataProvider = tempDataProvider; _serviceProvider = serviceProvider; _env = env;
    }

    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);
            var viewResult = _razorViewEngine.GetView(_env.WebRootPath, 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();
        }
    }

回复于 2024-04-28T14:13:11+08:00

Red的答案让我99％的方式，但如果你的意见在一个意想不到的位置，它不起作用 . 这是我对此的解决方法 .

using Microsoft.AspNetCore.Hosting;
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 Example
{
    public static class ControllerExtensions
    {
        public static async Task<string> RenderViewAsync<TModel>(this Controller controller, string viewName, TModel model, bool isPartial = 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 = GetViewEngineResult(controller, viewName, isPartial, viewEngine);

                if (viewResult.Success == false)
                {
                    throw new System.Exception($"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();
            }
        }

        private static ViewEngineResult GetViewEngineResult(Controller controller, string viewName, bool isPartial, IViewEngine viewEngine)
        {
            if (viewName.StartsWith("~/"))
            {
                var hostingEnv = controller.HttpContext.RequestServices.GetService(typeof(IHostingEnvironment)) as IHostingEnvironment;
                return viewEngine.GetView(hostingEnv.WebRootPath, viewName, !isPartial);
            }
            else
            {
                return viewEngine.FindView(controller.ControllerContext, viewName, !isPartial);

            }
        }
    }
}

这允许您使用它，如下所示：

var emailBody = await this.RenderViewAsync("~/My/Different/View.cshtml", myModel);

回复于 2024-04-28T14:13:11+08:00

在.NET Core中将视图返回为字符串

7 回答

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