c# - 将 ActionResult 呈现为字符串 - 输出顺序不正确

Question

我有一个尝试将 ActionResult 呈现为字符串的解决方案。我通过传入我自己的 HttpContext 来实现这一点，它将输出文本编写器替换为我自己的 TextWriter。

这就是问题所在 - 元素呈现无序。如果我通过直接通过浏览器查询来呈现部分 View ，它工作正常。如果我通过替代的文本编写器呈现它，razor View 中的任何 @Html.Action 元素都会首先呈现，无论它们在 View 中的位置如何。

所以，这是我的 Razor View :

@inherits System.Web.Mvc.WebViewPage<WebsitePresentationLayer.MgrScreenLayoutViewer>
@using  System.Web.Mvc.Html;

<div>
    @Model.DebugText
</div> 
@foreach (var item in @Model.Items)
{
    <div>@item.Title</div>
    @Html.Action(
                    "LayoutItem",
                    new
                    {
                        id = item.Id,
                        uniqueName = item.UniqueName
                    }
                  );

}

如果我直接通过浏览器查询 View ，它会以正确的顺序呈现:

• @Model.DebugText
• Item1.Title
• Item1 Action 渲染
• Item2.Title
• Item2 Action 渲染

如果我将其呈现给我的 TextWriter，它会按以下顺序呈现:

• Item1 Action 渲染
• Item2 Action 渲染
• @Model.DebugText
• Item1.Title
• Item2.Title

为什么？

以下是我如何替换文本编写器。 (我是从 ASP.NET WebForms 页面调用它的，所以已经有一个现有的 HttpContext)

public static class ActionResultExtensions
{
    internal class MyResponseWrapper : HttpResponseWrapper
    {
        private System.IO.TextWriter _textWriter;
        public MyResponseWrapper(HttpResponse wrappedResponse, System.IO.TextWriter textWriter)
            : base(wrappedResponse)
        {
            _textWriter = textWriter;
        }

        public override System.IO.TextWriter Output
        {
            get { return this._textWriter; }
            set { this._textWriter = value; }
        }
    }

    internal class MyHttpContextWrapper : HttpContextWrapper
    {
        private readonly System.IO.TextWriter _textWriter;
        public MyHttpContextWrapper(System.IO.TextWriter textWriter)
            : base(HttpContext.Current)
        {
            this._textWriter = textWriter;
        }

        public override HttpResponseBase Response
        {
            get
            {
                var httpResponse = HttpContext.Current.Response;
                return new MyResponseWrapper(httpResponse, this._textWriter);
            }
        }
    }


    public static void Render(this System.Web.Mvc.ActionResult result, System.IO.TextWriter textWriter, System.Web.Routing.RouteData routeData, System.Web.Mvc.ControllerBase controllerBase)
    {
        var httpContextWrapper = new MyHttpContextWrapper(textWriter);
        result.ExecuteResult(new System.Web.Mvc.ControllerContext(httpContextWrapper, routeData, controllerBase));
    }
}

public static class MvcUtils
{
    public static void RenderControllerAction<T>(Func<T, System.Web.Mvc.ActionResult> f, System.IO.TextWriter writer) where T : System.Web.Mvc.ControllerBase, new()
    {
        var controller = new T();
        // We have to initialise the RouteData so that it knows the name of the controller
        // This is used to locate the view
        var typeName = controller.GetType().Name;
        System.Text.RegularExpressions.Regex regex = new System.Text.RegularExpressions.Regex("(.*)Controller$");
        var match = regex.Match(typeName);
        if (match.Success)
        {
            typeName = match.Groups[1].Value;
        }
        var routeData = new System.Web.Routing.RouteData();
        routeData.Values.Add("controller", typeName);

        var actionResult = f(controller);
        actionResult.Render(writer, routeData, controller);
    }
}

然后我最终使用以下代码将其输出为字符串:

StringBuilder sb = new StringBuilder();
StringWriter stringWriter = new StringWriter(sb);

CMS.Website.MvcUtils.RenderControllerAction<PlayerGroupController>
(
   c => c.ScreenLayout(this.MgrPlayerGroupViewer.ScreenLayoutId),
   stringWriter
);
stringWriter.Flush();
var generatedString = sb.ToString();

---

我已经为 TextWriter 编写了一个拦截器，果然，它收到了三个对 Write(string)

的调用

• 写(LayoutItem 1 Action 内容)
• 写(LayoutItem 2 Action 内容)
• 写(Model.DebugText 和两个项目标题)

Answer 1

我大约 6 个月前经历过这个。目标是使用部分来填充 jquery 弹出对话框。

问题是 View 引擎想要按照它自己的尴尬顺序呈现它们...

试试这个。 LMK 如果需要澄清。

    public static string RenderPartialViewToString(Controller thisController, string viewName, object model)
    {
        // assign the model of the controller from which this method was called to the instance of the passed controller (a new instance, by the way)
        thisController.ViewData.Model = model;

        // initialize a string builder
        using (StringWriter sw = new StringWriter())
        {
            // find and load the view or partial view, pass it through the controller factory
            ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(thisController.ControllerContext, viewName);
            ViewContext viewContext = new ViewContext(thisController.ControllerContext, viewResult.View, thisController.ViewData, thisController.TempData, sw);

            // render it
            viewResult.View.Render(viewContext, sw);

            //return the razorized view/partial-view as a string
            return sw.ToString();
        }
    }