MVC 6 控制器中的 ControllerContext 和 ViewEngines 属性在哪里？

Question

我创建了一个新的 MVC6 项目并构建了一个新站点。目标是获得视图的渲染结果。我找到了以下代码，但我无法让它工作，因为我找不到 ControllerContext 和 ViewEngines.

这是我要重写的代码：

protected string RenderPartialViewToString(string viewName, object model)
{
    if (string.IsNullOrEmpty(viewName))
        viewName = ControllerContext.RouteData.GetRequiredString("action");

    ViewData.Model = model;

    using (StringWriter sw = new StringWriter())
    {
        ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(ControllerContext, viewName);
        ViewContext viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
        viewResult.View.Render(viewContext, sw);

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

Answer 1

Update: I'm updating this to work with .Net Core 2.x as the APIs have changed since 2015!

首先，我们可以利用 ASP.Net MVC Core 附带的内置依赖注入，它将为我们提供 ICompositeViewEngine 手动呈现视图所需的对象。因此，例如，控制器看起来像这样：

public class MyController : Controller
{
    private ICompositeViewEngine _viewEngine;

    public MyController(ICompositeViewEngine viewEngine)
    {
        _viewEngine = viewEngine;
    }

    //Rest of the controller code here
}

接下来，我们实际需要渲染视图的代码。请注意，它现在是一个 async 方法，因为我们将在内部进行异步调用：

private async Task<string> RenderPartialViewToString(string viewName, object model)
{
    if (string.IsNullOrEmpty(viewName))
        viewName = ControllerContext.ActionDescriptor.ActionName;

    ViewData.Model = model;

    using (var writer = new StringWriter())
    {
        ViewEngineResult viewResult = 
            _viewEngine.FindView(ControllerContext, viewName, false);

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

        await viewResult.View.RenderAsync(viewContext);

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

调用方法，就这么简单：

public async Task<IActionResult> Index()
{
    var model = new TestModel
    {
        SomeProperty = "whatever"
    }

    var renderedView = await RenderPartialViewToString("NameOfView", model);

    //Do what you want with the renderedView here

    return View();
}

Answer 2

已发布的 dotnet core 1.0 已更改，此版本的上述代码适用于 1.0 RTM。

protected string RenderPartialViewToString(string viewName, object model)
{
    if (string.IsNullOrEmpty(viewName))
        viewName = ControllerContext.ActionDescriptor.DisplayName;

    ViewData.Model = model;

    using (StringWriter sw = new StringWriter())
    {
        var engine = _serviceProvider.GetService(typeof(ICompositeViewEngine)) as ICompositeViewEngine; // Resolver.GetService(typeof(ICompositeViewEngine)) as ICompositeViewEngine;
        ViewEngineResult viewResult = engine.FindView(ControllerContext, viewName, false);

        ViewContext viewContext = new ViewContext(
            ControllerContext,
            viewResult.View,
            ViewData,
            TempData,
            sw,
            new HtmlHelperOptions() //Added this parameter in
        );

        //Everything is async now!
        var t = viewResult.View.RenderAsync(viewContext);
        t.Wait();

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

编译此代码需要这些用法：

using System.IO;
using Microsoft.AspNetCore.Mvc.ViewEngines;
using Microsoft.AspNetCore.Mvc.ViewFeatures;

我还必须向控制器构造函数添加一个 DI 接口：

IServiceProvider serviceProvider

我的帐户构造函数现在看起来像这样：

public AccountController(
    UserManager<ApplicationUser> userManager,
    SignInManager<ApplicationUser> signInManager,
    IEmailSender emailSender,
    ISmsSender smsSender,
    ILoggerFactory loggerFactory,
    IServiceProvider serviceProvider)
{
    _userManager = userManager;
    _signInManager = signInManager;
    _emailSender = emailSender;
    _smsSender = smsSender;
    _logger = loggerFactory.CreateLogger<AccountController>();
    _serviceProvider = serviceProvider;
}

Answer 3

Martin Tomes 提供的解决方案对我有用，但我不得不更换：

ViewEngineResult viewResult = engine.FindView(ControllerContext, viewName, false);

与

ViewEngineResult viewResult = engine.GetView(_env.WebRootPath, viewName, false);

同样在控制器构造函数中必须添加

private IHostingEnvironment _env;

public AccountController(IHostingEnvironment env)
{
    _env = env;
}

Answer 4

Martin Tomes 的解决方案效果很好。我的更改：删除了 serviceProvider 并通过 DI 在构造函数中获取 ICompositeViewEngine。构造函数看起来像：

private readonly ICompositeViewEngine _viewEngine;

        public AccountController(

                UserManager<ApplicationUser> userManager,
                SignInManager<ApplicationUser> signInManager,
                IEmailSender emailSender,
                ISmsSender smsSender,
                ILoggerFactory loggerFactory,
                ICompositeViewEngine viewEngine)
            {
                _userManager = userManager;
                _signInManager = signInManager;
                _emailSender = emailSender;
                _smsSender = smsSender;
                _logger = loggerFactory.CreateLogger<AccountController>();
                _viewEngine = viewEngine;;
            }

并放

ViewEngineResult viewResult = _viewEngine.FindView(ControllerContext, viewName, false);

而不是

var engine = _serviceProvider.GetService(typeof(ICompositeViewEngine)) as ICompositeViewEngine; // Resolver.GetService(typeof(ICompositeViewEngine)) as ICompositeViewEngine;
ViewEngineResult viewResult = engine.FindView(ControllerContext, viewName, false);

Answer 5

DavidG提供的解决方案很好，但我将其更改为独立服务。

namespace WebApplication.Services
{
    public interface IViewRenderService
    {
        Task<string> RenderPartialViewToString(Controller Controller, string viewName, object model);
    }

    public class ViewRenderService: IViewRenderService
    {
        private readonly ICompositeViewEngine _viewEngine;

        public ViewRenderService(ICompositeViewEngine viewEngine)
        {
            _viewEngine = viewEngine;
        }
       public async Task<string> RenderPartialViewToString(Controller Controller, string viewName, object model)
            {
                if (string.IsNullOrEmpty(viewName))
                    viewName = Controller.ControllerContext.ActionDescriptor.ActionName;

                Controller.ViewData.Model = model;

                using (var writer = new StringWriter())
                {
                    ViewEngineResult viewResult =
                        _viewEngine.FindView(Controller.ControllerContext, viewName, false);

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

                    await viewResult.View.RenderAsync(viewContext);

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

将服务添加到启动：

services.AddScoped<IViewRenderService, ViewRenderService>();

现在像这样使用依赖注入：

public class MyController : Controller
{
private readonly IViewRenderService _viewRender;

public MyController(IViewRenderService viewRender)
{
    _viewRender = viewRender;
}

//Rest of the controller code here
}

现在您可以像这样在操作方法中使用它：

var renderedView = await_viewRender.RenderPartialViewToString(this,"nameofview", model);

MVC 6 控制器中的 ControllerContext 和 ViewEngines 属性在哪里？

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

c#

asp.net-mvc

asp.net-core-mvc

asp.net-core