I've created my own Razor view class, thus:
public abstract class MyWebViewPage : System.Web.Mvc.WebViewPage
{
public MyWebViewPage()
{
}
}
I use this class in my cshtml file, thus:
#inherits MyWebViewPage
<html>
...
</html>
I want to determine the physical location of the cshtml file in the constructor of the class, but don't seem to be able to get a handle on anything in the base class that might tell me. Any ideas?
I'm trying to work out the Area name and folder name of the view (e.g. Areas/MyArea/Views/MyViews/MyView.cshtml). The pertinent bits being "MyArea" and "MyViews".
I'm currently porting an application to use Razor views and I used to be able to do what I needed because the class name of the view was something along the lines of:
ASP_Areas_MyArea_Views_MyViews_MyView
But with Razor it's just:
ASP_MyView
You should be able to look at the VirtualPath property. It will not be available when the constructor gets invoked, but you can override ConfigurePage and do any processing there.
Related
I'm new with ASP.Net Core (3.0 in this case) and I´m trying to create a menu that is visible on all views of a WebApplication, is created dynamically and must be populated only once. Below i explain the steps and try outs i did to reach the goal needed (if required i can share the code I'm using).
This is what i did:
In a simple way, using the "_Layout.cshtml" page, i created a static HTML menu and made all other views simply inherit that layout. So far, so good;
Next challenge comes from the fact that the menu items are dynamically created after a User has logged-in, which i managed to overcome by setting a ModelView inside a controller (HomeController.cs with Index action in this case), and then delivering it to the view. For this case works OK, because the default page is ~\Home\Index\, problem is when i change to a different view with a different controller, the menu has to be rendered again, and so i have to replicate the code (a problem dealt create a BaseController and BaseModel based on this post along side the OnActionExecuted to host the menu generating code)
Now, the biggest problem is the fact that i can only populate the menu once, after the user logs-in. Each time there is a redirect between different controllers/views (post-back of same controller/view works fine), the model is null inside the OnActionExecuted, I tried using ViewData, ViewBag, TemData, but all are null.
So, my question is, how to keep that specific data alive and shared, basically across all the views, and only gets populated once (after each user login) between redirects from different views?
I have been reading around and found several solutions besides the one i did, but i did not found any that could keep data alive throughout the user session the way I need:
ViewBag, ViewData and TempData
Can the shared layout view have a controller in ASP.NET MVC?
Pass data to layout that are common to all pages
To sum up, my flow at this moment, is like this:
User Logged-in
Redirect to default: ~\Home\Index
MenuModelView.cs for the menu gets built and HomeController.cs returns to Index.cshtml with the model attached to it.
Index.cshtml receives the populated ModelView and it uses _Layout.cshtml
The _Layout.cshtml builds the HTML tags for the menu based on the MenuModelView.cs data
User navigates to a different view and steps 3 to 5 are repeated from a specific controller/view
If you want to create a control that can be accessible in all pages without changing every controller, I strongly suggest creating a view component. For a view component has no relationship with your controller, but can access dependencies like database and full HTTP context.
For example, you want to build a custom nav menu, you can just create a view component named NavHeader
using Microsoft.AspNetCore.Mvc;
namespace YourProject.Views.Shared.Components.NavHeader
{
public class NavHeader : ViewComponent
{
public NavHeader(YourDbContext context)
{
// you can access your dependencies, like database.
}
public IViewComponentResult Invoke()
{
// your own logic. You can access HTTPContext here.
var model = new YourOwnModel();
return View(model);
}
}
}
And just call it in any view or layout.
<!DOCTYPE html>
<html>
<head>
<title>Example</title>
</head>
<body>
#*Render your component like this*#
<vc:nav-header></vc:nav-header>
</body>
For more details about view component, please reference:
https://learn.microsoft.com/en-us/aspnet/core/mvc/views/view-components?view=aspnetcore-3.1
https://anduin.aiursoft.com/post/2020/1/4/share-view-component-between-different-aspnet-core-web-project
I'm working on a ASP.NET MVC 3 application, but I'm rather new to MVC in general.
I have a partial view in a my application layout view that needs to have data passed to it. this will appear on every page. Is there a way to make this happen so I don't have to load that data into the view model for every action in the entire site?
As in, if a user navigates to Mysite/admin/settings, I would like to have the partial view on the layout be able to somehow receive the data that it needs without me needing to put that code in the Settings action in the Admin controller.
On this same note, how do you pass data to the layout view of an application anyway?
In these situations I usually use a base ViewModel for my Views
public class ApplicationViewModel
{
public string UserName {get; set;}
....
}
public class SettingsViewModel : ApplicationViewModel
{
}
all your views would inherit from that ViewModel. Your layout would expect it as well
_layout.cshtml:
#model ApplicationViewModel
....
<h1>hello #Model.UserName</h1>
hopefully this answers your question
Partial only renders a view. You need to provide the model manually.
You can create an action for the view you want and render it with Html.Action( actionName ).
Make an action for example menu which will create a model that will be provided to the menu view.
Now you can call the #Html.Action("menu") from wherever, and it will be rendered autonomously. (you can ofcourse provide a controller name as well, and even custom routeData)
You might also want to set Layout = null; in the view to avoid using the master layout of the whole site.
This is how I pass a value to the partial view from my layout page:
Layout page code:
Html.RenderPartial("_SubMenuLeft", new ViewDataDictionary { {"category", "MMG"} });
and in my _SubMenuLeft.cshtml (partial view)
#if (ViewData["category"] == "MMG")
{
...
}
Hope it helps someone for future reference.
I am creating a custom MVC framework.
I verrrrry loosely modeled it after the codeIgniter framework, but it's ground-up custom for the most part.
I'm at the point where I have URL's routing to the appropriate controller actions, but I'm stuck at the point where I generate a view that can utilize data generated by the controller.
I have views defined (static HTML with inline php ready to populate dynamic data), and I have the destructor of my base controller require()'ing the view in order to populate the browser with the view... here's the code:
public function __destruct()
{
if ($this->bSuppressView === false)
{
require(APP_PATH.'views/layout/header.php');
require(APP_PATH.'views/'.$this->sController.'/view.'.$this->sController.'.'.$this->sAction.'.php');
require(APP_PATH.'views/layout/footer.php');
}
}
Basically, when the controller is done executing, the teardown process of the base controller will then include the global header view, the controller's action's view, and then the global footer view, which should populate the webpage with everything for the URL that was requested...
HOWEVER, I cannot access any globally defined variables from the embedded php in the view code. In my bootstrap class, I define a bunch of local variables such as my config variable, etc., but the view seems to consider those variables undefined. Additionally, i'm unsure how to allow the view to access data that the controller may have generated. Where do I "stick" it to make it available to the view?
Let me know if this isn't clear, and i'll update.
Thanks!
UPDATE: I've discovered that while doing it this way, the "environment" of the views is within the controller object, which, as far as I can tell is a great thing! I don't have to propogate anything anywhere but in the controller, and I can use "$this->" in the views to get access to anything public or private from within the controller class!!!
That leaves the question: is this "normally" how it's done in MVC? What's the BEST way to propogate a view? I think this will suit my purposes, and I will post back if I discover a limitation to just treating the embedded view php as "within the scope of the calling controller"...
The way this is generally done, is that the view is actually an object. You pass that object you're variables, and that view object takes the template you gave it, includes it so that it's in the current scope, and grab the output into a variable using output buffering.
To give you a basic idea:
// controller object
$this->set('key','val');
$this->render('mytemplate');
// controller base class
$view = new View;
$view->setData($this->getData());
// view class
class View {
....
function render() {
ob_start();
include $this->resolveTemplate();
$out = ob_get_contents();
ob_end_clean();
return $out;
}
I want to create an abstract base view (with lots of virtual methods with cshtml)
and then create a derived view that optionally overrides these methods to customise the view:
for example:
override void Header(string title) {
<div class="massive">#title</div>
}
How can this be achieved with razor?
(doesn't everybody want/need to do this?)
I believe you would be better off using Helper methods than trying for an inheritance model on views. Use Scott Gu's blog for an introduction:
http://weblogs.asp.net/scottgu/archive/2011/05/12/asp-net-mvc-3-and-the-helper-syntax-within-razor.aspx
http://www.asp.net/mvc/tutorials/creating-custom-html-helpers-cs
It doesn't quite work like that out of the box, although I'm sure with some effort you could get that to work.
Instead, you create Layouts with defined Sections and then derive other Layouts from those adding new sections if you need to. Then, a view will declare which layout it is using via
#{
Layout = "_Layout.cshtml" // app relative path to layout
}
and can provide markup for any sections as needed using
#section SectionName {
<p>I'm markup to go into a section in the layout this view is using</p>
}
You can pass data via ViewData and/or ViewBag, so you could use them to pass delegates if you wanted to do that.
Alternatively, you might decide add extension methods to HtmlHelper, UrlHelper or even create a WebViewPage derived from System.Web.Mvc.WebViewPage and add any additional properties/methods onto your derived type then set it as the pageBaseType in the <system.web.webPages.razor> in the web.config used by the views.
Simply use sections and layouts. You would define a layout containing some default contents into sections which could be overridden in child views. You could use the IsSectionDefined method in the layout to test whether a child view overrides this section and if not provide default content.
The cleanest way I found is to use a #helper declared in App_Code
which takes delegates as arguments:
#helper Example(Func<int, HelperResult> fn1, Func<int, HelperResult> fn2) {
<div>#fn1(100)</div>
<div>#fn2(200)</div>
}
and then create a view with helper functions:
#helper Custom1(int x) { <span class="small">#x</span> }
#helper Custom2(int x) { <span class="big">#x</span> }
and then invoke shared helper like this:
#Example(Custom1, Custom2)
and, if required, the shared helper can implement a default behaviour if the delegate is null
this is much messier than simply implementing a derived view with a few overriden virtual helpers - but at least it works, is strongly typed, and doesn't use dynamic
Building a WP7 app using MVVM light for my view models. I'm using the ViewModelLocator that gets added when you add the library through NuGet. Works great but now I need to get access to a ViewModel from code.
In my code the user clicks a button and I need to search the MainViewModel (which contains several view models) and find one based on the criteria the user entered.
Normally I would just response to the Click event of the button but I don't have an instance variable of the ViewModelLocator class to get a hold of the MainViewModel to perform the search. With the default template (non-MVVMLight) for Windows Phone 7, the App class has a static variable to the main view model so you can access it anytime with App.ViewModel.
There's some talk from twitter about using commands which would be good, but at some point I have to perform a code search across multiple vms to get the results I need. Probably need to inject a ISearchViewModel service into the View or something to make this work.
Here's the implementation of ViewModelLocator that is provided:
public class ViewModelLocator
{
private static MainViewModel _main;
public ViewModelLocator()
{
_main = new MainViewModel();
}
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance",
"CA1822:MarkMembersAsStatic",
Justification = "This non-static member is needed for data binding purposes.")]
public MainViewModel Main
{
get
{
return _main;
}
}
}
So from the code behind of another view, how do you get access to Main (MainViewModel contains all the lists of data and has a search method I call)? Or Should you?
Just wondering how people are solving this type of problem?
Thanks.
In MVVM-Light the ViewModelLocator is provided as an application resource. Therefore you can still directly access it, but the syntax is different. If you look at your App.xaml you should see this piece of code somewhere.
<Application.Resources>
<vm:ViewModelLocator x:Key="Locator"
d:IsDataSource="True" />
</Application.Resources>
From anywhere in your application you can access the App's resources and therefore also the MainViewModel with this piece of code:
(App.Current.Resources["Locator"] as ViewModelLocator).Main
This works for any application resource.
If you created the ViewModelLocator as in the template you have static references to the ViewModels. The mvvmlocatorproperty-snippet creates ViewModel-properties like this.
This means that you could just instantiate a new ViewModelLocator to locate the ViewModels in your code behind button click. It will always be the same viewmodels independent of the different instances of the ViewModelLocator
To access the MainViewModel from your code you can add this property to your class:
public ViewModel.MainViewModel myContext { get { return (DataContext as ViewModel.MainViewModel); } }
Then you can just use myContext.[whatever]
You can just use ViewModelLocator.MainViewModelStatic. Default template for MVVMLight have a static property for each your viewmodel.