I am used to ASP.NET where each user control would have its own codebehind, and you do things related to that usercontrol in that codebehind C#.net file, so you can reference the usercontrol anywhere you like.
I am new to ASP.NET MVC, and I added an ascx control, and I can not seem to figure out where do I write the code for setting viewdata specific to that control? I have this ascx control inside my master page, so the setting up for viewdata for that control should be at such a place that is available to all pages, so I can not do it inside Index() or something.
If you need a partial view (.ascx) that has its own controller ("code-behind") associated with it, consider using RenderAction() rather than RenderPartial().
http://blogs.intesoft.net/post/2009/02/renderaction-versus-renderpartial-aspnet-mvc.aspx
Related
I have a small confusion in Asp.Net MVC
How rendering works in Asp.net MVC? We invoke View function - > Which will find the view and ask ViewEngine to parse it. Because of ViewEngine final outcome is HTML.
1)Whatever ViewData we create its available inside View. My understanding is ViewData and View function both are part of controller base class which makes ViewData available inside View function. Is it correct?
2)Finally Whats the point with WebViewPage class. ViewData keyword we use inside View(.cshtml) page is coming from the WebViewPage class. What role WebViewPage plays here.
I will really appreciate If you can point me with some good resource to understand the same
1) ViewData is merely a dictionary of objects that you can fill in the Controller and retrieve within the view. Since it is a dictionary of objects you need to cast the data back into the type it was to make full use of it.
2) WebViewPage is the base type of a razor page. It is the defined class which razor pages are compiled into at runtime. The web.config inside the views folder specifies the pageBaseType of the razor pages specifically to WebViewPage. These are two good resources regarding why its use and how you can extend it. Link1 and Link2.
Go peek inside he source code that renders the views
visit msdn
I'm trying to migrate an existing ASP.NET Webforms 3.5 application into an ASP.NET MVC 3 application. That means, I attempt to convert existing .aspx pages with webcontrols and codebehind recpectively with controller logic and razor views.
At the moment I'm focusing on the master page (to get an analogue layout.cshtml for all other razor views).
For example I've replaced controls like asp:Menu, asp:LoginView with partial views and #Html.Action to invoke the controller action, run some code that has been in the codebehind of that masterpage before and return that partial view.
But now I'm getting lost with many web controls of the masterpage that have been set in/visible, depending on the code behind. For example there are two asp:panels in the master page that have been switched in/visible depending on the visited page.
The problem is that in razor views I don't have web controls and in controllers I cannot set attributes/properties (like private int counter;).
Thus I don't know how to carry on...
I hope you have got some ideas or experience with this situation.
Please ask if any information is missing.
You can either set properties of the Model or ViewData in the Controller and then use these in the Razor view with #if
e.g.
On the controller:
public ActionResult Index()
{
ViewBag.Foo = IsThisFoo();
View();
}
In the View:
#if (ViewBag.Foo) {
<p>This is foo</p>
}
else
{
<p>This is bar</p>
}
nb: best practice would be to do it as part of a strongly typed Model for the view
What is the difference between viewstate and viewdata in mvc?
I was just going through the MVC framework & the exact question popped up in my head.. I understand the difference as below.
ASP.Net & MVC are two different worlds. But looking closely they are not. The concepts of web remains the same and it just the way to write the code. Ok letz compare them
ASP.Net
.aspx -- So this is the view which contains the html to be rendered in the browser
.aspx.cs -- as we know this is the code behind for doing all the manipulation of the html
So on top of that we have the BO with our properties and which is bound to the controls using databind.
So here comes the ViewState which remembers the data bound to the controls back and forth between the postback.
MVC
View - this holds all the HTML code which in turn is still a .aspx or ascx file
Controller - has the logic behind the HTML. Inside that you have the action methods for performing the specific actions.
So here instead of BO, you have the Models with the same properties which is given to the View to render itself in a different syntax instead of a databind.
Now ViewData is used to bind the anonymous data between the controller and the view.
Comparatively ViewData is more organized and easy to use but apart from that they serve a similar purpose but different in few ways. Like Viewstate is persistent between postbacks and ViewData is not as MVC is stateless.
Hope this explains to an extent
ViewState and ViewData can handle some complex objects.
ViewState is within page lifecycle while ViewData works in very different way. ViewData can be passed to the target view.
Please refer here for understanding of viewState:
http://msdn.microsoft.com/en-us/library/ms972976.aspx
for viewData:
http://www.asp.net/mvc/tutorials/asp-net-mvc-views-overview-cs
hope that helps
View state is used only in ASP.net forms,controls and Page life cycle. View state is used by ASP.net framework to manage control states.
View Data is a dataset or Data which is passed to your View - to dipslay HTML data in MVC,
Viewstate is not used in MVC. Please refer above mentioned links for more details.
I'm porting an application from WebForms to MVC.
I have a WebForms UserControl that is used throughout the site and which contains presentational and business logic, and in particular some 'initizliation' logic (in the Page_Load)
My understanding of MVC UerControls is that they have no dedicated controller and thus contain no logic, and the logic is added to the controller of the viewpage to which the UserControl is added.
Now, I don;t want to have to write the initialization logic in my ViewPage, as this UserControl appears on several pages, thus duplication of logic.
I don't think I can user a MasterPage, as the UserControl can be rendered either vertically to the left of the page or hozontally at the top of the page depending on what page it is. This would require 2 MasterPage's, and again duplication of logic.
Do I have any other options?
This is a good case to use the RenderAction html helper. Much better, grab the Microsoft MVC futures and use the RenderAction method. Basically it lets you call a controller action within a view, which is alot more like how UserControls work than RenderPartial.
Bleh, I guess I should do it properly and pass in a object via my controller's viewdata rather than hacky-slash it.
I make heavy use of View Components in some of the larger applications I've built in Monorail - What is the equivalent approach in ASP.Net MVC for a view component, that can support sections etc.?
Actually you have several options to create the equivalent of a ViewComponent in ASP.NET MVC, depending in the complexity of your component. I use these two approaches which are the more mvc-ish of the options I am aware of.
1:
The simplest thing is to create a ViewUserControl and display it using Html.RenderPartial with the helper. The ViewUserControl is a simple piece of markup with no backing controller (I think you can put a codebehind file if you want).
Optionally, you can pass a model object or the entire ViewData dictionary to the view when calling RenderPartial, like this:
<% Html.RenderPartial("TopBar", model); %>
"TopBar" is an ascx page. This works anywhere, in master pages and in normal views.
2:
If you want your component to have more complicated logic or to access datasources, IoC, etc, then you can use Html.RenderAction which is an extension method found in the Microsoft.Web.Mvc assembly. I am using this out of the mvccontrib distribution. It works like this, you need to create a normal controller with all the logic you need, then create some views and all of these things become your component, for example:
public class AboutComponentController : Controller {
public IRepository Repository{ get; set; }
public ActionResult Detail() {
var lastEvent = Repository.FindAll<Auditoria>().FirstOrDefault();
return View(lastEvent);
}
}
Notice how I have a reference to an IRepository which is going to be injected with IoC (Windsor in my case) and I can do anything a normal controller would do.
Now, in any page (master or normal) where you want to use your component, import Microsoft.Web.Mvc and call Html.RenderAction with the appropriate parameters. This will create a mini mvc pipeline that creates the controller, resolves the view, etc., just like a Monorail ViewComponent. I prefer to use the lambda based variation of the method, like this:
<% Html.RenderAction<AboutComponentController>(x => x.Detail("a message"));%>
Unfortunately, the only way to pass parameters is to use the method call itself, which in turn must be unique in the controller. Still needs some work to resemble a ViewComponent.
I don't use masterpages or layouts in the views of my components since they are composition elements themselves.
Remember that when using the Webforms view engine, you can have strongly typed views if you like to have intellisense when using the Model variable in code blocks.
The beauty of this is that you can mix view engines with these approaches, I usually create the components in nvelocity and display them in aspx pages, etc.
I now there can be issues with caching of the partial views but I haven't run into any so far. I am sure there are other options (like subcontrollers in mvccontrib) but this is usually enough for simple cases. Of course you can use normal ASP.net components in your aspx view pages but that would be cheating right? hehe. I hope it helps.
Phil Haack blogged about creating areas to group controllers into sub-folders/sections similar to MonoRails.