Question

This seemed easier in Web Forms; I’d have a user control, with the logic in the code-behind, and I could just drop it on a page.

But apparently code-behinds are a no-no in MVC, and the logic is in controllers. I’m a little confused about how logic for a user control is “wired up”.

I want to display an RSS Feed user control. So I have a page:

<%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage" %>

<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
    Home Page
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
    <p>
        <% Html.RenderPartial("RssFeed"); %>
    </p>
</asp:Content>

I have my user control:

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewPage<SyndicationFeed>" %>
<%@ Import Namespace="System.ServiceModel.Syndication" %>

<p>
    <%: ViewData.Model.Title.Text %>
</p>

<div>
    <% foreach (var item in ViewData.Model.Items)
    {
       string url = item.Links[0].Uri.OriginalString;
    %>
    <p><a href='<%= url %>'><b><%= item.Title.Text %></b></a></p>

    <% } %>
</div>

And I have this code that I need to run to get the rss data:

using (XmlReader reader = XmlReader.Create(ConfigurationManager.AppSettings["RssFeed"]))
{
    SyndicationFeed rssData = SyndicationFeed.Load(reader);

    return View(rssData);
}

But where does it go? In the controller for the page that contains the control?

Answer 1

To sum it up, this is how you can do it

[HttpGet, ChildActionOnly]
// put this in RssController
public ActionResult RssFeed()
{
    // prepare the model
    SyndicationFeed rssData;
    using (XmlReader reader = XmlReader.Create(ConfigurationManager.AppSettings["RssFeed"])) 
    {
        rssData = SyndicationFeed.Load(reader);
    }

    return PartialView(rssData);
}

Usage:

<% Html.RenderAction("RssFeed", "Rss"); %>

And put a check into your ASCX if the Model you are sending in is null and if so, skip everything so it won’t render anything. If you leave it like you have it now, it will end in an exception if the Model sent in is null.