asp.net-mvc - 关于 ViewEngines.Engines.FindView 方法和 masterName 参数的问题

Question

如果我将 null 传递给最后一个参数 masterName，则此方法效果很好，我的类中的 View 设置源自 RazorViewEngine 工作，一切都很好。出于好奇，masterName 参数有何用途？我首先想到也许它是用于layout.cshtml，但是；当我向它传递一个布局时，它会抛出异常......关于如何使用它的任何想法，它在寻找什么？

自定义 View 引擎(几乎没有笑)

public class CustomRazorViewEngine : RazorViewEngine
{
    private readonly string[] NewViewFormats = new[]
                                                   {
                                                       "~/Views/Messaging/{0}.cshtml"
                                                   };

    public CustomRazorViewEngine()
    {
        base.ViewLocationFormats = base.ViewLocationFormats.Union(NewViewFormats).ToArray();
    }
}

public string RenderViewToString(string viewName, object model, ControllerContext controllerContext,
                                     string masterName)
    {
        if (string.IsNullOrEmpty(viewName))

            viewName = controllerContext.RouteData.GetRequiredString("action");
        controllerContext.Controller.ViewData.Model = model;
        using (var stringWriter = new StringWriter())
        {
            ViewEngineResult viewEngineResult = ViewEngines.Engines.FindView(controllerContext, viewName, masterName);
            var viewContext = new ViewContext(controllerContext, viewEngineResult.View,
                                              controllerContext.Controller.ViewData,
                                              controllerContext.Controller.TempData,
                                              stringWriter);
            viewEngineResult.View.Render(viewContext, stringWriter);
            return stringWriter.GetStringBuilder().ToString();
        }
    }

Answer 1

经过更多调试后，我发现了似乎是正确的答案。首先让我声明 masterName 参数是“布局”的名称，也就是说正在渲染的 View 将使用。这里的问题是布局必须能够定位。因此，下面的代码可以按预期工作，而不是我原来的帖子中的 ViewEngine 代码。

public string RenderViewToString(string viewName, object model, ControllerContext controllerContext,
                                     string masterName)
    {
        if (string.IsNullOrEmpty(viewName))

            viewName = controllerContext.RouteData.GetRequiredString("action");
        controllerContext.Controller.ViewData.Model = model;
        using (var stringWriter = new StringWriter())
        {
            ViewEngineResult viewEngineResult = ViewEngines.Engines.FindView(controllerContext, viewName, masterName);

            var viewContext = new ViewContext(controllerContext, viewEngineResult.View,
                                              controllerContext.Controller.ViewData,
                                              controllerContext.Controller.TempData,
                                              stringWriter);
            viewEngineResult.View.Render(viewContext, stringWriter);
            return stringWriter.GetStringBuilder().ToString();
        }
    }

public class CustomRazorViewEngine : RazorViewEngine
{
    private readonly string[] NewMasterViewFormats = new[]
                                                         {
                                                             "~/Views/Messaging/Layouts/{0}.cshtml"
                                                         };

    private readonly string[] NewViewFormats = new[]
                                                   {
                                                       "~/Views/Messaging/{0}.cshtml"
                                                   };

    public CustomRazorViewEngine()
    {
        base.ViewLocationFormats = base.ViewLocationFormats.Union(NewViewFormats).ToArray();
        base.MasterLocationFormats = base.MasterLocationFormats.Union(NewMasterViewFormats).ToArray();
    }
}

现在打电话时

string returnViewToString = _viewUtils.RenderViewToString("RegistrationEmail", new RegistrationEmailModel
                                                                               {                                                                                      UserName = userName
                                                                               },
                                                     this.ControllerContext,"_RegistrationEmailLayout");

一切都很顺利，并且我的传入 View 的布局(如果它存在于文件夹中)会被使用。这是我这一天的亮点...哈哈