Create UserControl in ASP.NET MVC4 - asp.net-mvc

Question

I develop a web application using ASP.NET MVC4 in VS2012, in that a HomeController as Views/Home/Index.aspx.
I created a user control as UC/UC_Menu.ascx in Views Folder.
In Index.aspx page, I coded in below and run ok.
<% Html.RenderPartial("~/Views/UC/UC_Menu.ascx"); %>
Now, I want to UC/UC_Menu.ascx load data in database. How could I do?

Answer 1

In ASP.NET MVC, views and partials are not supposed to be retrieving any data. They are designed for displaying data that has been retrieved by the corresponding controller under the form of a view model.
So basically you should create a view model that will be a projection of your data. For example:
public class MyViewModel
{
public string Foo { get; set; }
public string Bar { get; set; }
}
and then have your controller action fetch the data from the database and project it to the view model:
public class HomeController: Controller
{
public ActionResult Index()
{
MyViewModel model = ... go fetch from db
return View(model);
}
}
and now your Index.aspx view will be strongly typed to this view model and pass the model to your partial view:
<%# Page Title="" Language="C#" Inherits="System.Web.Mvc.ViewPage<MyNs.MyViewModel>" %>
and then pass the model to the partial for displaying:
<% Html.RenderPartial("~/Views/UC/UC_Menu.ascx", Model); %>
and your partial can now display the data:
<%# Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<MyNs.MyViewModel>" %>
<%= Html.DisplayFor(x => x.Foo) %>
<%= Html.DisplayFor(x => x.Bar) %>

Answer 2

Invoking "Child Actions" gives you encapsulation similar to "UserControls".
Note: "UserControls" is a term used in ASP.NET Web Forms. In MVC, you would call it a "PartialView".
You could create a child action on your controller, for example:
public class HomeController : Controller
{
[ChildActionOnly]
public ActionResult Menu()
{
var model = BuildModelFromDB();
return PartialView(model);
}
}
Then invoke it in your view, passing in the ActionName and ControllerName:
<%= Html.Action("Menu", "Home") %>