我正在尝试在 ASP.NET Core MVC 中使用 ICompositeViewEngine 来替换 System.Web.Mvc 中的 ViewEngine,因为它在 .NET Core 中不再可用。在这个项目中,我通常会尝试将 Web 表单从 ASP.NET 迁移到 ASP.NET Core。
我找到了以下解决方案:Where are the ControllerContext and ViewEngines properties in MVC 6 Controller?我相信这可以解决我的问题。我还在 github 问题中找到了与 ServiceProvider 类似的引擎创建:https://github.com/aspnet/Mvc/issues/3091
但是,我不确定我可能缺少哪些依赖项或框架,因为我是 .NET 的新手。我有以下命名空间:
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.ViewEngines;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.Extensions.DependencyInjection;
我认为这可能与我的问题有关。
我的原始代码是:
public static string RenderPartialToString(Controller controller, string viewName, object model)
{
controller.ViewData.Model = model;
using (StringWriter sw = new StringWriter())
{
ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(controller.ControllerContext, viewName);
ViewContext viewContext = new ViewContext(controller.ControllerContext, viewResult.View, controller.ViewData, controller.TempData, sw);
viewResult.View.Render(viewContext, sw);
return "document.write('" + sw.GetStringBuilder().Replace('\n', ' ').Replace('\r', ' ').Replace("'","\\'").ToString() + "');";
}
}
现在我正在尝试使用以下任一方法:
var engine = Resolver.GetService(typeof(ICompositeViewEngine)) as ICompositeViewEngine;
var engine2 = IServiceProvider.GetService(typeof(ICompositeViewEngine)) as ICompositeViewEngine;
我是否在正确的轨道上解决这个问题?有没有更简单的方法来替换 .NET Core 中的 System.Web.Mvc ViewEngines?我需要什么来修复 Resolver 和/或 ServiceProvider 的“在当前上下文中不存在”错误?
谢谢。我希望我能够遵循问题指南。
编辑:请让我知道我是否应该从我的代码中为这个问题包含任何其他内容。我目前正在阅读有关依赖注入(inject)的内容,以便更好地了解情况。
最佳答案
您基本上是在正确的轨道上。 ASP.NET Core 摆脱了许多静态对象,因此您不能执行 Resolver.GetService
之类的操作。 解析器
不存在。相反,使用 dependency injection系统。
如果您只需要从 Controller 访问 ICompositeViewEngine
,请将其注入(inject)构造函数:
public MyController(ICompositeViewEngine viewEngine)
{
// save a reference to viewEngine
}
如果你想要一个处理 Razor 到字符串渲染的离散服务,你需要在启动时注册它:
public void ConfigureServices(IServiceCollection services)
{
// (Other code...)
services.AddTransient<IViewRenderingService, ViewRenderingService>();
services.AddMvc();
}
服务本身看起来像这样:
using System;
using System.IO;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewEngines;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
public interface IViewRenderingService
{
string RenderPartialView(ActionContext context, string name, object model = null);
}
public class ViewRenderingService : IViewRenderingService
{
private readonly ICompositeViewEngine _viewEngine;
private readonly ITempDataProvider _tempDataProvider;
public ViewRenderingService(ICompositeViewEngine viewEngine, ITempDataProvider tempDataProvider)
{
_viewEngine = viewEngine;
_tempDataProvider = tempDataProvider;
}
public string RenderPartialView(ActionContext context, string name, object model)
{
var viewEngineResult = _viewEngine.FindView(context, name, false);
if (!viewEngineResult.Success)
{
throw new InvalidOperationException(string.Format("Couldn't find view '{0}'", name));
}
var view = viewEngineResult.View;
using (var output = new StringWriter())
{
var viewContext = new ViewContext(
context,
view,
new ViewDataDictionary(
new EmptyModelMetadataProvider(),
new ModelStateDictionary())
{
Model = model
},
new TempDataDictionary(
context.HttpContext,
_tempDataProvider),
output,
new HtmlHelperOptions());
view.RenderAsync(viewContext).GetAwaiter().GetResult();
return output.ToString();
}
}
}
要从 Controller 使用它,注入(inject)并调用它:
public class HomeController : Controller
{
private readonly IViewRenderingService _viewRenderingService;
public HomeController(IViewRenderingService viewRenderingService)
{
_viewRenderingService = viewRenderingService;
}
public IActionResult Index()
{
var result = _viewRenderingService.RenderPartialView(ControllerContext, "PartialViewName", model: null);
// do something with the string
return View();
}
}
如果您想完全在 MVC 之外使用 Razor,请参阅 this answer .
关于c# - Resolver 或 ServiceProvider 使用 ICompositeViewEngine 所需的依赖项,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/38749745/