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
Related
I keep reading that the MVC way to pass data from a controller to the view is done via a ViewModel, but what about passing data to _Layout.cshtml, like page title, meta description, article author, etc...
What's the MVC way to pass this kind of data? Should I just use ViewBag for them?
You have few ways:
ViewBag
ViewData
View Components
Injections (example below)
ViewBag and ViewData are quite easy to use, however not always convenient.
There is one big plus - you could set/read them in one place of view and read in another - for example, you could set them in your main view and read/display them in _lauout.cshtml.
View Components are the most interesting new feature in MVC Core (in my opinion) which allows you to create UI widgets.
There is a little bit more coding for ViewComponent (you need to create controller and view), but it's flexible feature (I like it) and easy to call in a place where you need it, just
#await Component.InvokeAsync("NameOfCOmponent").
Injections not my favorite, but sometime usfull - for example if you want display user name, you could just put the following code directly into your layout/view file:
#using System.Security.Claims
#using Microsoft.AspNetCore.Identity
#inject UserManager<ApplicationUser> userManager
#{
var userInfo = ((await userManager?.GetUserAsync(User))?.xxx);
// where 'xxx' is any property of ApplicationUser model
}
then you can use #userInfo in the same view to display that info.
More information:
Views Overview
Passing Data to Views
View Components
I have installed Umbraco 7 in MVC application. Have you achieved ever rendering MVC View from Surface Controller ? If it is possible to do how it can be done by passing model and passing a query string parameter to View ?
If I understand your question correctly, you need to use an approach called Route Hijacking, rather than surface controllers.
Simplified, the steps are:
Create a model matching a given Document Type.
Create a mapper to map an Umbraco IPublishedContent object to the model.
Create a controller that inherits Umbraco.Web.Mvc.RenderMvcController.
Override the Index action with a signature of ActionResult Index(Umbraco.Web.Models.RenderModel model).
Call the mapper, and return your view.
In your view / template, you will then be able to use
#model MyNewModel
instead of
#inherits Umbraco.Web.Mvc.UmbracoTemplatePage
Here is a very good tutorial / explanation on the approach.
Be sure to read the follow up post too
I would like to use the generic razor helper function Html.Partial to render views that have common html in them.
For instance, I have two views set up in Sitecore Payment Information.cshtml and Agent Payment Information.cshtml. These are rendered using the Sitecore rendering engine. Both of these views have very similar html in them that I would like to put in razor views not set in Sitecore and call them with #Html.Partial as appose to #Html.Sitecore().Rendering() as the latter forces me to set up a view and model in Sitecore which I am not sure is necessary.
My question is, is there anything that Sitecore does behind the scenes that makes it necessary to usethe #Html.Sitecore().Rendering() helper method instead of the #Html.Partial() helper method? Everything seems to work fine and I believe the entire view should get cached since the #Html.Partial call is nested inside either the Payment Information view or the Agent Payment information view set up in Sitecore.
Thanks in advance.
I have Html.Partial working in an MVC solution using Glass for ORM. There are two ways I've used this, one where the assumed model being passed to the partial is the same as the parent rendering and another where we create the model on the fly.
Assumes parent rendering model is passed:
#Html.Partial("~/Views/Components/MyPartialView.cshtml")
Instantiates a new model that is passed in:
#Html.Partial("~/Views/Components/Navigation/SecondaryNavigationRendering.cshtml", new SecondaryNavigation())
The parent view will need to have a mapped model in Sitecore. The secondary view does not have a mapped model in Sitecore but is typed to receive the model being passed (so in my first example that would be my IBasePage model, in my second it would be my SecondaryNavigation model).
Hope this helps.
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.
I'm trying to pass ViewData to my asp.net mvc masterpage for an mvc usercontrol that I keep on a masterpage. For example, I created a dropdownlist of names as an mvc usercontrol and I put that in my masterpage.
The problem I am running into is passing the ViewData to the masterpage. I found this article from Microsoft which has a decent solution but I was wondering if there are other "better" solutions out there. The thing I don't like about the solution in the link is that I have to change every controller to inherit from a new controller class.
http://www.asp.net/learn/MVC/tutorial-13-cs.aspx
Edit: The problem I am looking at is the fact that if I place a user control in my masterpage that relies on ViewData, I have to REPEATEDLY include that ViewData for every single page that uses said masterpage. It's possible the solution in the link above is the best solution but I was hoping there were other alternatives.
The master page already has access to the ViewData. If you want strongly typed access to it, you need to do two things:
Put the master page stuff in a base class (e.g. CommonViewData)
Have you master page inherit from the generic ViewMasterPage<> class:
" %>
Could you possibly use the OnActionExecuting method on a base controller class and populate the view data there?
Something like:
protected override void OnActionExecuting(ActionExecutingContext context)
{
context.Controller.ViewData.Model = GetDataForControl();
}
I haven't tried it so it's just a thought...
For what it's worth, I am using the method from that tutorial in a current project and it works very well.
What you can also do, if it is data that is somewhat static (like a menu that doesn't change much), is to put the object on the cache so your database isn't called for every controller initialisation.
I usually use an abstract controller class for my MasterPage, it is the best solution, because the MasterPage is like an "abstract view". But I override the MasgerPageController View() method to include the viewdata.
protected override ViewResult View(string viewName, string masterName, object model)
{
this.ViewData["menu"] = this.PagesRepository.GetPublishPages();
return base.View(viewName, masterName, model);
}
I don't quite get your problem...
The problem I am looking at is the fact that if I place a user control in my masterpage that relies on ViewData, I have to REPEATEDLY include that ViewData for every single page that uses said masterpage.
Well yeah... of course you do. If you have a usercontrol in your master page then of course you're going to have to pass the required data for that usercontrol for every action & view that uses that masterpage.
It's not like you have to repeat yourself if you are just inheriting from a base controller.
Is your issue the fact that some controllers have actions that both do and don't call views that derive from that particular masterpage? So therefore if you are implementing a base controller, the actions that don't use that particular masterpage will still have the viewdata for it...? (If all that makes sense ;-)
I think the solution suggested does work but not the ideal solution. If we put the code in the BaseController constructor it is going to be called even for Action methods which does not have a MasterPages (e.g Post methods and Ajax methods).
I think a better solution(not ideal) is to call Html.Action method in the Master page.