模块化 MVC 应用程序中的布局

Question

我用 ninject for MVC 为自己制作了一个模块化框架。

每个模块都可以注册自己的路由并包含自己的视图。

模块目录（dll 位置）：
~/Modules/<module name>/

模块视图位于内部：
<Module dir>/Views/
它们的排列方式与普通的 mvc 应用程序完全相同，IE 每个控制器都有一个文件夹和一个共享文件夹。

我想渲染一个带有布局的视图，但是我希望布局位置由核心框架设置（以便我可以更改主题）。

我有一个具有layout = _layout.cshtml 的视图，当我运行应用程序时它返回：

The layout page "_Layout.cshtml" could not be found at the following path: "~/Modules/Module2/Views/Home/_Layout.cshtml".

被调用的视图在这里~/Modules/Module2/Views/Home/Index.cshtml。但我希望它在另一个位置寻找布局而不是在每个视图中设置它。无论如何我可以在核心框架中做到这一点吗？请注意，我将它设置为 MasterLocationFormats 以查看共享，它显然没有（我通过在其中放置 _layout.cshtml 进行了测试）。

---

自定义视图引擎：

public NinjectRazorViewEngine(): base()
    {
        ViewLocationFormats = new[] {
            "~/Modules/%1/Views/{1}/{0}.cshtml",
            "~/Modules/%1/Views/{1}/{0}.vbhtml",
            "~/Modules/%1/Views/Shared/{0}.cshtml",
            "~/Modules/%1/Views/Shared/{0}.vbhtml"
        };

        MasterLocationFormats = new[] {
            "~/Modules/%1/Views/{1}/{0}.cshtml",
            "~/Modules/%1/Views/{1}/{0}.vbhtml",
            "~/Modules/%1/Views/Shared/{0}.cshtml",
            "~/Modules/%1/Views/Shared/{0}.vbhtml",
        };

        PartialViewLocationFormats = new[] {
            "~/Modules/%1/Views/{1}/{0}.cshtml",
            "~/Modules/%1/Views/{1}/{0}.vbhtml",
            "~/Modules/%1/Views/Shared/{0}.cshtml",
            "~/Modules/%1/Views/Shared/{0}.vbhtml"
        };

        PartialViewLocationFormats = ViewLocationFormats;
        AreaPartialViewLocationFormats = AreaViewLocationFormats;
    }

    protected override IView CreatePartialView(ControllerContext controllerContext, string partialPath)
    {
        object moduleName;
        if(controllerContext.RequestContext.RouteData.Values.TryGetValue("module",out moduleName))
            return base.CreatePartialView(controllerContext, partialPath.Replace("%1", (string)moduleName));
        return base.CreatePartialView(controllerContext, partialPath);
    }

    protected override IView CreateView(ControllerContext controllerContext, string viewPath, string masterPath)
    {
        object moduleName;
        if (controllerContext.RequestContext.RouteData.Values.TryGetValue("module", out moduleName))
            return base.CreateView(controllerContext, viewPath.Replace("%1", (string)moduleName), masterPath.Replace("%1", (string)moduleName));
        return base.CreateView(controllerContext, viewPath, masterPath);
    }

    protected override bool FileExists(ControllerContext controllerContext, string virtualPath)
    {
        object moduleName;
        if (controllerContext.RequestContext.RouteData.Values.TryGetValue("module", out moduleName))
            return base.FileExists(controllerContext, virtualPath.Replace("%1", (string)moduleName));
        return base.FileExists(controllerContext, virtualPath);
    }

Answer 1

这需要大量的工作。

必须对视图引擎进行更改以正确公开FindView 和FindPartialView 方法。问题中列出的方法是错误的。

viewEngineClass 应该是这样的

public NinjectRazorViewEngine(): base()
    {
        ViewLocationFormats = new[] {
            "~/Modules/{2}/Views/{1}/{0}.cshtml",
            "~/Modules/{2}/Views/{1}/{0}.vbhtml",
            "~/Modules/{2}/Views/Shared/{0}.cshtml",
            "~/Modules/{2}/Views/Shared/{0}.vbhtml",
            "~/Views/{1}/{0}.cshtml",
            "~/Views/{1}/{0}.vbhtml",
            "~/Views/Shared/{0}.cshtml",
            "~/Views/Shared/{0}.vbhtml"
        };

        MasterLocationFormats = new[] {
            "~/Modules/{2}/Views/{1}/{0}.cshtml",
            "~/Modules/{2}/Views/{1}/{0}.vbhtml",
            "~/Modules/{2}/Views/Shared/{0}.cshtml",
            "~/Modules/{2}/Views/Shared/{0}.vbhtml",
        };

        PartialViewLocationFormats = new[] {
            "~/Modules/{2}/Views/{1}/{0}.cshtml",
            "~/Modules/{2}/Views/{1}/{0}.vbhtml",
            "~/Modules/{2}/Views/Shared/{0}.cshtml",
            "~/Modules/{2}/Views/Shared/{0}.vbhtml",
            "~/Views/{1}/{0}.cshtml",
            "~/Views/{1}/{0}.vbhtml",
            "~/Views/Shared/{0}.cshtml",
            "~/Views/Shared/{0}.vbhtml"
        };

        PartialViewLocationFormats = ViewLocationFormats;
        AreaPartialViewLocationFormats = AreaViewLocationFormats;

        //Used to test cache
        //ViewLocationCache = new DefaultViewLocationCache();
    }
    public override ViewEngineResult FindPartialView(ControllerContext controllerContext, string partialViewName, bool useCache)
    {
        return FindView(controllerContext, partialViewName, "", useCache);
    }
    public override ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache)
    {
        //Implement defualt exceptions
        if(controllerContext == null)
            throw new ArgumentNullException("The controllerContext parameter is null");
        if(string.IsNullOrEmpty(viewName))
            throw new ArgumentException("The viewName parameter is null or empty.");

        //Check cache if specified
        if(useCache && this.ViewLocationCache != null){
            string cachedLocation = ViewLocationCache.GetViewLocation(controllerContext.HttpContext, generateCacheKey(controllerContext, viewName));
            if (!string.IsNullOrEmpty(cachedLocation))
                return new ViewEngineResult(CreateView(controllerContext, cachedLocation, masterName), this);
        }

        //Create arguments for location formatting
        string trimmedViewName = string.Empty;
        if (viewName.EndsWith(".cshtml"))
            trimmedViewName = viewName.Remove(viewName.Length - 7);
        else
            trimmedViewName = viewName;
        object[] args = new object[] { trimmedViewName, controllerContext.RouteData.GetRequiredString("controller"), controllerContext.RouteData.GetRequiredString("module") };

        //Attempt to locate file
        List<string> searchedLocations = new List<string>();
        foreach(string location in ViewLocationFormats){
            string formatedLocation = string.Format(location,args);
            searchedLocations.Add(formatedLocation);
            if (FileExists(controllerContext, formatedLocation))
            {
                //File has been found. Add to cache and return view
                if(this.ViewLocationCache != null)
                    ViewLocationCache.InsertViewLocation(controllerContext.HttpContext, generateCacheKey(controllerContext, viewName), formatedLocation);

                return new ViewEngineResult(CreateView(controllerContext, formatedLocation, masterName), this);
            }
        }

        //Couldnt find view, return searched locations
        return new ViewEngineResult(searchedLocations);
    }
    public string generateCacheKey(ControllerContext controllerContext, string viewName)
    {
        return string.Format("{0}|{1}", controllerContext.RouteData.GetRequiredString("module"), viewName);
    }

然后您需要像这样实现自定义System.Web.Mvc.WebViewPage<T>：

public abstract class WebViewPage<T> : System.Web.Mvc.WebViewPage<T>
{
    public override string Layout
    {
        get
        {
            return base.Layout;
        }
        set
        {
            NinjectRazorViewEngine viewEngine = new NinjectRazorViewEngine();
            System.Web.Mvc.ViewEngineResult engineResult = viewEngine.FindView(this.ViewContext.Controller.ControllerContext, value, string.Empty, true);
            System.Web.Mvc.RazorView razorView = engineResult.View as System.Web.Mvc.RazorView;
            if (razorView == null)
            {
                string searchedIn = "";
                foreach (string item in engineResult.SearchedLocations)
                {
                    searchedIn += item + "\n";
                }
                throw new HttpException(500, "Could not find views in locations:\n" + searchedIn);
            }
            base.Layout = razorView.ViewPath;
        }
    }
}

希望有帮助:)

Answer 2

您可以实现自己的 ViewEngine，它将在自定义位置查找视图。

public class MyViewEngine : RazorViewEngine {
   public MyViewEngine() {
       this.MasterLocationFormats = new string[] {
           "PATH TO YOUR LAYOUT FILES", "ALTERNATIVE PATH"
       }
   }
}

然后在您的应用程序启动期间（例如在 Global.asax.cs 中）设置您的应用程序以使用您的自定义引擎

ViewEngines.Engines.Clear();
ViewEngines.Engines.Add(new ThemableViewEngine());

Answer 3

您真的应该尝试使用带有RazorGenerator 的预编译视图。

编译视图允许您将模块作为单个 DLL 删除，这比将所有内容（如 cshtml 视图）带入 DLL 更容易，此外，您可以在启动时或运行时使用 MEF 或任何其他反射机制，使您的 MVC 应用真正模块化并减少耦合。

我发现自己在模块化网站上这种实现并不划算。