Is it possible for an ASP.NET MVC controller to create a new instance of a different controller and effectively delegate resonsibility to that?
Let's say for example that I have two controllers in the /Controllers/ directory:
public class HomeController : Controller
{
public ActionResult Index()
{
var otherController = new OtherController();
return otherController.ShowNumberOfThings(100);
}
}
public class OtherController : Controller
{
public ActionResult ShowNumberOfThings(int index)
{
return View(index);
}
}
...and a View called Views/Other/ShowNumberOfThings.aspx:
<%# Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="ViewPage<int>" %>
Number of things: <%= Model.ToString() %>
When I hit the url:
http://localhost/Home/Index
I want to be presented with a page that reads:
"Number of things: 100"
I would like to be able to persist temporary data between controller redirections without being forced to use the session object (TempData[""] uses the session object for cross-controller redirections). My real world case has a complex object which needs passing (not just an int) so using a URL/Cookie is out of the question, and session state is a no-no.
In WebForms at least we could use Server.Transfer and maintain any state in the HttpContext.Items collection. In MVC the only option I can see is to call the controller method directly passing in required arguments.
At the moment it's having trouble trying to resolve the view folder as the "context" is still running under the HomeController.
I guess where I am going with this is trying to cludge ASP.NET MVC into acting like a FrontContoller.
Any ideas?
EDIT
In the end we had to serialise everything into a session and use that. A shame, but I have heard that MVC2 will support serialising objects into a ViewState.
If you want to be presented with "Number of things: 100" when you hit the Index action why not directly render the corresponding view:
public class HomeController : Controller
{
public ActionResult Index()
{
return View("~Views/Other/ShowNumberOfThings.aspx", 100);
}
}
I think it would be preferred to use.
return RedirectToAction("Controller", "Action")
However I'm guessing you want to maintain the Url Home/Index.
If you're looking at the FrontController pattern then you should investigate writing a Custom ControllerFactory which inherits from DefaultControllerFactory then Override the CreateController method.
You can register your factory using the code below.
protected void Application_Start()
{
ControllerBuilder.Current.SetControllerFactory(new MyCustomControllerFactory();
RegisterRoutes(RouteTable.Routes);
}
In the Controller factory you have access to the RequestContext so you can change the RouteData as needed and delegate to the correct controller.
You could of course just set a a Custom route for Home/Index which goes to OtherController.ShowNumberOfThings()
routes.MapRoute("Home", "Home/Index/{id}",
new {controller = "Other", action = "ShowNumberOfThings", id = 100});
a different approach would be the use of partial views
instead of ~Views/Other/ShowNumberOfThings.aspx
you could put your view in ~Views/shared/ShowNumberOfThings.ascx
have both views ~Views/Other/ShowNumberOfThings.aspx and ~Views/Home/Index.aspx implement the partial view
public class HomeController : Controller
{
public ActionResult Index()
{
return View(100);
}
}
public class OtherController : Controller
{
public ActionResult ShowNumberOfThings(int index)
{
return View(index);
}
}
and in both views implement the partial view
<% Html.RenderPartial("~Views/shared/ShowNumberOfThings.ascx", ViewData.Model); %>
you can change the int for any object that will be passed to the model
Another possibility (similar to partial views) is to use Html.RenderAction. This allows for different view model classes and separate controller methods.
<% Html.RenderAction("yourActionName", "yourControllerName", routeValues); %>
Related
I have an app with many widgets and their content depends on the user requesting specific route. Simply put: if widget action is requested, its content must be rendered, otherwise it's empty. Consider routes/actions like this:
~/MyApp/Index -> without model; app HTML, without any widgets
~/MyApp/Foo/{id} -> uses FooModel; if ModelState is valid, returns
Index HTML with injected partial view of Foo's widget to div#foo;
otherwise redirects to Index.
~/MyApp/Bar/{id} -> same as Foo, but different model and widget
My foo action :
public ActionResult Foo(string id) {
if (ModelState.IsValid) {
var response = FooService.GetData(id);
// Inject Foo widget to Index
}
return RedirectToAction("Index");
}
I know that it is possible to use ViewBag or other means to send variables and using the condition to decide whether to render partial view or not. But... there should be a better way to do this, right?
I use MVC's Html.RenderActionResult when I want to build shared views with non-trivial binding logic (calling the database, composing complex objects, etc). The binding logic for each widget is contained in a PartialViewResult method, which is called from the *.cshtml file using Html.RenderAction().
ContentController:
public ActionResult Index(int id)
{
var indexViewModel = new IndexViewModel
{
Id = id,
Title = "My Title",
SubHeader = "Wow its 2016"
};
return View(indexViewModel);
}
public PartialViewResult PopularContent(int id)
{
var popularContentViewModel = new List<PopularContentViewModel>();
// query by id to get popular content items
return PartialView("_PopularContent", popularContentViewModel);
}
public PartialViewResult Widget2(int id)
{
return PartialView("_Widget2Partial");
}
Index.cshtml:
#model StackOverflow.RenderAction.ViewModels.IndexViewModel
<h1>#Model.Title</h1>
<h2>#Model.SubHeader</h2>
--RenderAction will call out to the specified route.
--Note the use of the Id parameter from the viewmodel.
#{Html.RenderAction("PopularContent", "Content", new {Model.Id});}
ASP.NET MVC Attribute Routing could a be a nice solution for this:
In your controller:
public class WidgetController : Controller
{
[Route("myapp/foowidget", Name = "FooWidget")]
public ActionResult FooWidget()
{
//create any model and return any view or partial or redirect
}
[Route("myapp/boowidget/{id:int}", Name = "BooWidget")]
public ActionResult BooWidget(int id)
{
//create any model and return any view or partial or redirect
}
}
And then in a View, you can call the Route by name:
#Url.RouteUrl("FooWidget")
or
#Url.RouteUrl("BooWidget")
or
#Html.RenderPartial("FooWidget")
#Url.RouteUrl("BooWidget") will render or concatenate the id that is in current url, if url is /myapp/something/id, because of your Route attribute definition: "myapp/boowidget/{id:int}". In fact #Url.RouteUrl("BooWidget") might extract the id from any current url of the format /controllerName/action/id, though you will have to test for sure.
And notice how you can have a separation of concerns with your WidgetController and your url Routes are not dependent on that controller's name in any way. That is a nice feature of Attribute Routing, you can declare custom routes as well as organize your controllers and break from nameing convention dependency of a controllerName being part of the url controllerName/action a user sees in their browser.
In regards to Html.RenderPartial, I am not sure if RenderPartial "connects" or will be able to route to your RouteName like "FooWidget". If it does great.
If not your solution is this:
public class WidgetController : Controller
{
public ActionResult FooWidget()
{
//model, you choose, return a partial
}
public ActionResult RedirectUser()
{
//do a redirect
}
public ActionResult BooWidget()
{
//any model, any partial
}
public ActionResult BooWidget(int id)
{
//any model, any partial
}
}
Each method in your controller is single purpose, has a distinct signature and does one thing, no conditions to pass in and no decisions required.
I am Creating a new partial view in MVC 3 as this functionality is required through out my application.Is it possible to have a separate controller for my partial view only
Yes, you can. Create controller (consider to disable non-child action calls if you need to use controller only for partial view):
public class FooController : Controller
{
[ChildActionOnly]
public PartialViewResult Bar()
{
var model = new BarModel();
return PartialView("_Bar", model);
}
}
And use it
#Html.RenderAction("Bar", "Foo")
Every page in my site should have some of the same data, similar to how in SO every page displays info about the current user at the top of the page. The way I implemented this was to have a base controller class that all my controllers derive from. In that base controller's constructor I put my model in the ViewBag, and then my layout page uses that.
I'm running into problems with this because my layouts aren't strongly typed. For example, I have to construct new HtmlHelpers in the layout page:
#{var layoutHtml = new HtmlHelper<LayoutModel>(Html.ViewContext, Html.ViewDataContainer); }
#* OK, now we can use the html helper... *#
#layoutHtml.TextAreaFor(model => model.Feedback)
I really don't want to have to have my models subclass from a layout model, since that would force each action to fill out the shared model data individually, but manually creating HtmlHelpers also seems like a bad idea.
Any thoughts?
I might be wrong, but shouldn't you use partial views for this?
Your solution looks way too complicated.
A base controller is a great way to start. I would also introduce a base viewmodel. The base viewmodel would contain user specific information.
public abstract class BaseController : Controller
{
public string CurrentAccountName
{
get
{
return (HttpContext.User == null) ? null : HttpContext.User.Identity.Name;
}
}
public T CreateViewModel<T>() where T : BaseViewModel, new()
{
T viewModel = new T
{
UserName = CurrentAccountName
};
return viewModel;
}
}
public abstract class BaseViewModel
{
public string UserName { get; set; }
}
Then on each request you would populate your viewmodel with user specific information and whatever information is required for the view. MyViewModel is just a viewmodel that inherits from BaseViewModel.
public class MyController : BaseController
{
public ActionResult Index()
{
MyViewModel viewModel = CreateViewModel<MyViewModel>();
return View(viewModel);
}
}
In the master view I would pass in the BaseViewModel and the View I would pass in the inherited MyViewModel.
Now you have access to your user information in your master view and can pass it to a partial or render it directly to the page.
you can define multiple Layouts which you can use in your appropiate views! Just include them like so:
#{
Layout = "~/Views/Shared/_MySubLayout.cshtml";
}
i believe you can use RenderAction to solve this problem. Because information this action will display is common on all pages, you can put it in BaseController and call it from your site master. it will compute its own model and return that model to partial view which can be strongly typed and you don't have to instantiate htmlHelper the way you are doing now.
I want to get a value from the user session and display it in the site.master file. How can I do this so that every view page has this value? Do I have to place ViewData["MyValue"] in every controller action? Is there a global way of doing this in one place so I don't have to have the same code in every controller action?
You could write an action filter attribute and decorate your controller with it:
public class CustomFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
base.OnActionExecuted(filterContext);
filterContext.Controller.ViewData["MyValue"] = "some value";
}
}
And then decorate the controller with this attribute:
[CustomFilter]
public class MyController: Controller
{
// actions
}
This will ensure that ViewData["MyValue"] will be set on all action belonging to this controller.
<%= Session["MyValue"] %> in the master page
public ActionResult Index(){
var dataContext = new DataEvidencijaDataContext();
MembershipUser myObject = Membership.GetUser();
string KorisnickoIme = myObject.UserName.ToString();
var user = from i in dataContext.korisniks
where i.korisnik1 == KorisnickoIme
select i;
ViewData.Add("user", user);
return View(user);
}
In master page i put this
<%= Html.RenderPartial("profPredmeti", ViewData["user"])%>
but this is not work
You can use RenderAction for this to delegate menu rendering to some controller. Another option is to have your controller (or base controller class, or action filter) put the menu object into ViewData, and then your master page will do
<% Html.RenderPartial("MenuRenderView", ViewData["menu"]) %>
where MenuRenderView.aspx partial view consumes the menu object from ViewData["menu"]. What does this object contain depends on your database/code.
The approach that I have taken in the past is to have a base controller class from which all the other controllers inherit. In that base controller class, you can add items into ViewData after the controller is initialized:
protected override void Initialize(System.Web.Routing.RequestContext requestContext)
{
base.Initialize(requestContext);
ViewData.Add("CommonPageData", CommonPageData);
}
The "CommonPageData" in this case is a property or type CommonPageData (a custom class) whose properties are lazy-loaded. One of the properties is a navigation item collection that is consumed on the master page.
User RenderPartial for the Menu, but you're gonna need to pass in the ViewData the datasource for the menu all the time, a solution is to make an abstract BaseController and to put the datasource in the ViewData in the constructor of that base controller
all the controllers will inherit from the base controller
I have this block sitting in my Site.Master page:
<script runat="server" type="text/C#">
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
MasterModel = SiteMasterViewData.Get();
}
protected SiteMasterViewData MasterModel;
</script>
That Get() method is a static factory method tacked on to the View Data class. All of this is embarrassing but here we are.