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    <p>The Category parameter is being picked up from the following routing entry</p> <pre><code> routes.MapRoute(null, "{category}", // Matches ~/Football or ~/AnythingWithNoSlash new { controller = "Products", action = "List", page = 1 } ); </code></pre> <p>so if /Football is entered then it is supplied as a parameter to the ViewResult Menu in the </p> <p>which in turn calls</p> <pre><code> public ViewResult List(string category, int page = 1) { var productsToShow = (category == null) ? productsRepository.Products : productsRepository.Products.Where(x =&gt; x.Category == category); var viewModel = new ProductsListViewModel { Products = productsToShow.Skip((page - 1) * PageSize).Take(PageSize).ToList(), PagingInfo = new PagingInfo { CurrentPage = page, ItemsPerPage = PageSize, TotalItems = productsToShow.Count() }, CurrentCategory = category }; return View(viewModel); // Passed to view as ViewData.Model (or simply Model) } </code></pre> <p>so later within the view master when the render action is called</p> <pre><code> &lt;% Html.RenderAction("Menu", "Nav"); %&gt; </code></pre> <p>it can pick up on the category parameter in the route i.e. {category}</p> <pre><code> public ViewResult Menu(string category) { // Just so we don't have to write this code twice Func&lt;string, NavLink&gt; makeLink = categoryName =&gt; new NavLink { Text = categoryName ?? "Home", RouteValues = new RouteValueDictionary(new { controller = "Products", action = "List", category = categoryName, page = 1 }), IsSelected = (categoryName == category) }; // Put a Home link at the top List&lt;NavLink&gt; navLinks = new List&lt;NavLink&gt;(); navLinks.Add(makeLink(null)); // Add a link for each distinct category var categories = productsRepository.Products.Select(x =&gt; x.Category); foreach (string categoryName in categories.Distinct().OrderBy(x =&gt; x)) navLinks.Add(makeLink(categoryName)); return View(navLinks); } } </code></pre>
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    1. POWhere do the parameters come from for action that gets invoked by Html.RenderAction?
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    1. USNicholas Murray
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    1. POWhere do the parameters come from for action that gets invoked by Html.RenderAction?
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    1. CO@Nicholas: One more question: I understand why Products.List() gets called with the right parameter. I also understand now why NavController.Menu() is getting called. But why is the NavController.Menu() getting called with the correct parameter {category}? The routing entry specified "ProductsController" and "List" as default action to be used. Nowhere is there any mention of the NavController and the "Menu" action in my routing instructions. (referring to your first source code quote. There is no "Nav" or "Menu" in there, but the category is still getting passed on.
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      1. USBlub
    2. CO@Blub - it is getting called with the parameter, as the parameter is available via the url - just as if it was index.asp?category=chess and you had a method that called Request.QueryString("category"). If in the routing you changed routes.MapRoute(null, "{category}", to routes.MapRoute(null, "{catgory}", then when you step through the code you will see category being null.
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      1. USNicholas Murray
    3. CO@Nicholas: So, Request.QueryString() is always getting called *automatically* then, right? Because of the MVC framework. Whatever action I could ever write, it will get called to get url parameters?
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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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