How to set a Default Route (To an Area) in MVC
This one interested me, and I finally had a chance to look into it. Other folks apparently haven't understood that this is an issue with finding the view, not an issue with the routing itself - and that's probably because your question title indicates that it's about routing.
In any case, because this is a View-related issue, the only way to get what you want is to override the default view engine. Normally, when you do this, it's for the simple purpose of switching your view engine (i.e. to Spark, NHaml, etc.). In this case, it's not the View-creation logic we need to override, but the FindPartialView and FindView methods in the VirtualPathProviderViewEngine class.
You can thank your lucky stars that these methods are in fact virtual, because everything else in the VirtualPathProviderViewEngine is not even accessible - it's private, and that makes it very annoying to override the find logic because you have to basically rewrite half of the code that's already been written if you want it to play nice with the location cache and the location formats. After some digging in Reflector I finally managed to come up with a working solution.
What I've done here is to first create an abstract AreaAwareViewEngine that derives directly from VirtualPathProviderViewEngine instead of WebFormViewEngine. I did this so that if you want to create Spark views instead (or whatever), you can still use this class as the base type.
The code below is pretty long-winded, so to give you a quick summary of what it actually does: It lets you put a {2} into the location format, which corresponds to the area name, the same way {1} corresponds to the controller name. That's it! That's what we had to write all this code for:
BaseAreaAwareViewEngine.cs
public abstract class BaseAreaAwareViewEngine : VirtualPathProviderViewEngine
{
private static readonly string[] EmptyLocations = { };
public override ViewEngineResult FindView(
ControllerContext controllerContext, string viewName,
string masterName, bool useCache)
{
if (controllerContext == null)
{
throw new ArgumentNullException("controllerContext");
}
if (string.IsNullOrEmpty(viewName))
{
throw new ArgumentNullException(viewName,
"Value cannot be null or empty.");
}
string area = getArea(controllerContext);
return FindAreaView(controllerContext, area, viewName,
masterName, useCache);
}
public override ViewEngineResult FindPartialView(
ControllerContext controllerContext, string partialViewName,
bool useCache)
{
if (controllerContext == null)
{
throw new ArgumentNullException("controllerContext");
}
if (string.IsNullOrEmpty(partialViewName))
{
throw new ArgumentNullException(partialViewName,
"Value cannot be null or empty.");
}
string area = getArea(controllerContext);
return FindAreaPartialView(controllerContext, area,
partialViewName, useCache);
}
protected virtual ViewEngineResult FindAreaView(
ControllerContext controllerContext, string areaName, string viewName,
string masterName, bool useCache)
{
string controllerName =
controllerContext.RouteData.GetRequiredString("controller");
string[] searchedViewPaths;
string viewPath = GetPath(controllerContext, ViewLocationFormats,
"ViewLocationFormats", viewName, controllerName, areaName, "View",
useCache, out searchedViewPaths);
string[] searchedMasterPaths;
string masterPath = GetPath(controllerContext, MasterLocationFormats,
"MasterLocationFormats", masterName, controllerName, areaName,
"Master", useCache, out searchedMasterPaths);
if (!string.IsNullOrEmpty(viewPath) &&
(!string.IsNullOrEmpty(masterPath) ||
string.IsNullOrEmpty(masterName)))
{
return new ViewEngineResult(CreateView(controllerContext, viewPath,
masterPath), this);
}
return new ViewEngineResult(
searchedViewPaths.Union<string>(searchedMasterPaths));
}
protected virtual ViewEngineResult FindAreaPartialView(
ControllerContext controllerContext, string areaName,
string viewName, bool useCache)
{
string controllerName =
controllerContext.RouteData.GetRequiredString("controller");
string[] searchedViewPaths;
string partialViewPath = GetPath(controllerContext,
ViewLocationFormats, "PartialViewLocationFormats", viewName,
controllerName, areaName, "Partial", useCache,
out searchedViewPaths);
if (!string.IsNullOrEmpty(partialViewPath))
{
return new ViewEngineResult(CreatePartialView(controllerContext,
partialViewPath), this);
}
return new ViewEngineResult(searchedViewPaths);
}
protected string CreateCacheKey(string prefix, string name,
string controller, string area)
{
return string.Format(CultureInfo.InvariantCulture,
":ViewCacheEntry:{0}:{1}:{2}:{3}:{4}:",
base.GetType().AssemblyQualifiedName,
prefix, name, controller, area);
}
protected string GetPath(ControllerContext controllerContext,
string[] locations, string locationsPropertyName, string name,
string controllerName, string areaName, string cacheKeyPrefix,
bool useCache, out string[] searchedLocations)
{
searchedLocations = EmptyLocations;
if (string.IsNullOrEmpty(name))
{
return string.Empty;
}
if ((locations == null) || (locations.Length == 0))
{
throw new InvalidOperationException(string.Format("The property " +
"'{0}' cannot be null or empty.", locationsPropertyName));
}
bool isSpecificPath = IsSpecificPath(name);
string key = CreateCacheKey(cacheKeyPrefix, name,
isSpecificPath ? string.Empty : controllerName,
isSpecificPath ? string.Empty : areaName);
if (useCache)
{
string viewLocation = ViewLocationCache.GetViewLocation(
controllerContext.HttpContext, key);
if (viewLocation != null)
{
return viewLocation;
}
}
if (!isSpecificPath)
{
return GetPathFromGeneralName(controllerContext, locations, name,
controllerName, areaName, key, ref searchedLocations);
}
return GetPathFromSpecificName(controllerContext, name, key,
ref searchedLocations);
}
protected string GetPathFromGeneralName(ControllerContext controllerContext,
string[] locations, string name, string controllerName,
string areaName, string cacheKey, ref string[] searchedLocations)
{
string virtualPath = string.Empty;
searchedLocations = new string[locations.Length];
for (int i = 0; i < locations.Length; i++)
{
if (string.IsNullOrEmpty(areaName) && locations[i].Contains("{2}"))
{
continue;
}
string testPath = string.Format(CultureInfo.InvariantCulture,
locations[i], name, controllerName, areaName);
if (FileExists(controllerContext, testPath))
{
searchedLocations = EmptyLocations;
virtualPath = testPath;
ViewLocationCache.InsertViewLocation(
controllerContext.HttpContext, cacheKey, virtualPath);
return virtualPath;
}
searchedLocations[i] = testPath;
}
return virtualPath;
}
protected string GetPathFromSpecificName(
ControllerContext controllerContext, string name, string cacheKey,
ref string[] searchedLocations)
{
string virtualPath = name;
if (!FileExists(controllerContext, name))
{
virtualPath = string.Empty;
searchedLocations = new string[] { name };
}
ViewLocationCache.InsertViewLocation(controllerContext.HttpContext,
cacheKey, virtualPath);
return virtualPath;
}
protected string getArea(ControllerContext controllerContext)
{
// First try to get area from a RouteValue override, like one specified in the Defaults arg to a Route.
object areaO;
controllerContext.RouteData.Values.TryGetValue("area", out areaO);
// If not specified, try to get it from the Controller's namespace
if (areaO != null)
return (string)areaO;
string namespa = controllerContext.Controller.GetType().Namespace;
int areaStart = namespa.IndexOf("Areas.");
if (areaStart == -1)
return null;
areaStart += 6;
int areaEnd = namespa.IndexOf('.', areaStart + 1);
string area = namespa.Substring(areaStart, areaEnd - areaStart);
return area;
}
protected static bool IsSpecificPath(string name)
{
char ch = name[0];
if (ch != '~')
{
return (ch == '/');
}
return true;
}
}
Now as stated, this isn't a concrete engine, so you have to create that as well. This part, fortunately, is much easier, all we need to do is set the default formats and actually create the views:
AreaAwareViewEngine.cs
public class AreaAwareViewEngine : BaseAreaAwareViewEngine
{
public AreaAwareViewEngine()
{
MasterLocationFormats = new string[]
{
"~/Areas/{2}/Views/{1}/{0}.master",
"~/Areas/{2}/Views/{1}/{0}.cshtml",
"~/Areas/{2}/Views/Shared/{0}.master",
"~/Areas/{2}/Views/Shared/{0}.cshtml",
"~/Views/{1}/{0}.master",
"~/Views/{1}/{0}.cshtml",
"~/Views/Shared/{0}.master"
"~/Views/Shared/{0}.cshtml"
};
ViewLocationFormats = new string[]
{
"~/Areas/{2}/Views/{1}/{0}.aspx",
"~/Areas/{2}/Views/{1}/{0}.ascx",
"~/Areas/{2}/Views/{1}/{0}.cshtml",
"~/Areas/{2}/Views/Shared/{0}.aspx",
"~/Areas/{2}/Views/Shared/{0}.ascx",
"~/Areas/{2}/Views/Shared/{0}.cshtml",
"~/Views/{1}/{0}.aspx",
"~/Views/{1}/{0}.ascx",
"~/Views/{1}/{0}.cshtml",
"~/Views/Shared/{0}.aspx"
"~/Views/Shared/{0}.ascx"
"~/Views/Shared/{0}.cshtml"
};
PartialViewLocationFormats = ViewLocationFormats;
}
protected override IView CreatePartialView(
ControllerContext controllerContext, string partialPath)
{
if (partialPath.EndsWith(".cshtml"))
return new System.Web.Mvc.RazorView(controllerContext, partialPath, null, false, null);
else
return new WebFormView(controllerContext, partialPath);
}
protected override IView CreateView(ControllerContext controllerContext,
string viewPath, string masterPath)
{
if (viewPath.EndsWith(".cshtml"))
return new RazorView(controllerContext, viewPath, masterPath, false, null);
else
return new WebFormView(controllerContext, viewPath, masterPath);
}
}
Note that we've added few entries to the standard ViewLocationFormats. These are the new {2} entries, where the {2} will be mapped to the area we put in the RouteData. I've left the MasterLocationFormats alone, but obviously you can change that if you want.
Now modify your global.asax to register this view engine:
Global.asax.cs
protected void Application_Start()
{
RegisterRoutes(RouteTable.Routes);
ViewEngines.Engines.Clear();
ViewEngines.Engines.Add(new AreaAwareViewEngine());
}
...and register the default route:
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
"Area",
"",
new { area = "AreaZ", controller = "Default", action = "ActionY" }
);
routes.MapRoute(
"Default",
"{controller}/{action}/{id}",
new { controller = "Home", action = "Index", id = "" }
);
}
Now Create the AreaController we just referenced:
DefaultController.cs (in ~/Controllers/)
public class DefaultController : Controller
{
public ActionResult ActionY()
{
return View("TestView");
}
}
Obviously we need the directory structure and view to go with it - we'll keep this super simple:
TestView.aspx (in ~/Areas/AreaZ/Views/Default/ or ~/Areas/AreaZ/Views/Shared/)
<%@ Page Title="" Language="C#" Inherits="System.Web.Mvc.ViewPage" %>
<h2>TestView</h2>
This is a test view in AreaZ.
And that's it. Finally, we're done.
For the most part, you should be able to just take the BaseAreaAwareViewEngine and AreaAwareViewEngine and drop it into any MVC project, so even though it took a lot of code to get this done, you only have to write it once. After that, it's just a matter of editing a few lines in global.asax.cs and creating your site structure.
This is how I did it. I don't know why MapRoute() doesn't allow you to set the area, but it does return the route object so you can continue to make any additional changes you would like. I use this because I have a modular MVC site that is sold to enterprise customers and they need to be able to drop dlls into the bin folder to add new modules. I allow them to change the "HomeArea" in the AppSettings config.
var route = routes.MapRoute(
"Home_Default",
"",
new {controller = "Home", action = "index" },
new[] { "IPC.Web.Core.Controllers" }
);
route.DataTokens["area"] = area;
Edit: You can try this as well in your AreaRegistration.RegisterArea for the area you want the user going to by default. I haven't tested it but AreaRegistrationContext.MapRoute does sets route.DataTokens["area"] = this.AreaName; for you.
context.MapRoute(
"Home_Default",
"",
new {controller = "Home", action = "index" },
new[] { "IPC.Web.Core.Controllers" }
);