用于动态驱动内容的ASP.NET MVC呈现部分（Widgets）

Question

I am receiving the following error in ASP.NET MVC. "the following sections have been defined but have not been rendered for the layout page" - Now I know what the error is about, but can't figure a way around it in fact it probably should work but I don't know why it won't.

I have an index.cshtml page which renders all dynamically driven DB content. Pages can contain widgets (Reusable blocks on content). The index.cshtml code is below:

    @{
    Layout = AppSettings.LayoutFileDirectory + "/" + PageDAL.GetLayoutFileForPage(Model.Page);
    string currentSection = string.Empty;
}

    @if(!string.IsNullOrEmpty(Model.Page.PageTitle))
    {
           <h3>@Model.Page.PageTitle</h3>
    }


@Html.Raw(Model.Page.PageText)



@foreach (var item in Model.Page.WidgetsInPages)
{
    //if(IsSectionDefined(item.WidgetSection))
    //{

        string sectionName = item.WidgetSection;
        //don't want to redefine section
        if (currentSection!= sectionName)
        {
            DefineSection(sectionName, () =>
            {
                //render all this sections widgets
                foreach (var insider in Model.Page.WidgetsInPages.Where(w => w.WidgetSection == sectionName).OrderBy(w => w.WidgetSortOrder))
                {
                    if (insider.Widget.WidgetFile != null)
                    {
                        Write(Html.Partial(AppSettings.WidgetTemplatesDirectory + "/" + insider.Widget.WidgetFile, item.Widget));
                        //Write(Html.Partial(AppSettings.WidgetTemplatesDirectory + "/" + insider.Widget.WidgetFile, new {Widget=item.Widget}));
                    }

                }
            });
            currentSection = sectionName;
        }

    //}
}

Now I have a _DefaultTheme.cshtml with the following sections. (This is the primary layout page)

<div class="header">
      @RenderSection("_HeaderSection", false)
</div>



    <div class="container">
        @RenderSection("_AboveBodySection", false)
        @RenderBody()
        @RenderSection("_BelowBodySection", false)
    </div>

    @RenderSection("_AfterBodySection", false)

    <footer class="footer">
    <div class="container">
        @RenderSection("_FooterSection",false)
        @Html.Raw(FrontEnd.PopulateFooter(Model.Website))
    </div>

    </footer>

Adding widgets to the any page which has the _DefaultTheme layout works perfectly fine, but when I start inheriting pages it becomes an issue. I now have another page _DefaultThemeArticles.cshtml the master page is _DefaultTheme.cshtml

The _DefaultThemeArticles.cshtml contains this:

@{ 
    Layout = "~/Themes/_DefaultTheme.cshtml";
}


<div class="container">
    @RenderBody()
</div>

Now the error occurs when adding Widgets to any page which has this layout. I get this error:

The following sections have been defined but have not been rendered for the layout page "~/Themes/_DefaultThemeArticles.cshtml": "_BelowBodySection".

But the section _BelowBodySection has been defined in the master page, why would it not work here?.

Answer 1

The problem is that in your layout page, _DefaultTheme.cshtml , by writing all of these:

@RenderSection("_HeaderSection", false)
@RenderSection("_AboveBodySection", false)
@RenderSection("_BelowBodySection", false)
@RenderSection("_AfterBodySection", false)
@RenderSection("_FooterSection",false)

You are asserting that in any child page, like _DefaultThemeArticles , there must be a section defined for each of the above. If Razor doesn't find a particular section defined (in your case _BelowBodySection ) in the child page, it throws the error. You can use the following Razor to solve this:

@if (IsSectionDefined("_BelowBodySection"))
{
    @RenderSection("_BelowBodySection")
}

This will only render the section if it exists.

Hope this helps.