I am currently trying to migrate an ASP.net MVC 5 project to MVC 6.
How would I migrate the following code:
public static class SectionExtensions
{
public static HelperResult RenderSection(this WebPageBase webPage, [RazorSection] string name, Func<dynamic, HelperResult> defaultContents)
{
return webPage.IsSectionDefined(name) ? webPage.RenderSection(name) : defaultContents(null);
}
}
[RazorSection] is part of the JetBrains.Annotations assembly.
Instead of WebPageBase I used RazorPage in Microsoft.AspNet.Mvc.Razor
namespace Stackoverflow
{
public static class SectionExtensions
{
public static IHtmlContent RenderSection(this RazorPage page, [RazorSection] string name, Func<dynamic, IHtmlContent> defaultContents)
{
return page.IsSectionDefined(name) ? page.RenderSection(name) : defaultContents(null);
}
}
}
Then reference the class in the razor page #using static Stackoverflow.SessionExtensions, and call it like so:
#this.RenderSection("extra", #<span>This is the default!</span>))
An alternative way would be to just do this in the view (I prefer this way, seems a lot simpler):
#if (IsSectionDefined("extra"))
{
#RenderSection("extra", required: false)
}
else
{
<span>This is the default!</span>
}
I hope this helps.
Update 1 (from comments)
by referencing the namespace
#using Stackoverflow
you don't have to include the static keyword, but when calling it, you will have to reference the actual class in the namespace and also pass 'this' into the function.
#SectionExtensions.RenderSection(this, "extra", #<span>This is the default!</span>)
Update 2
There is a bug in razor that does not allow you to call template delegates Func <dynamic, object> e = #<span>#item</span>; within a section. Please see https://github.com/aspnet/Razor/issues/672
A current workaround:
public static class SectionExtensions
{
public static IHtmlContent RenderSection(this RazorPage page, [RazorSection] string name, IHtmlContent defaultContents)
{
return page.IsSectionDefined(name) ? page.RenderSection(name) : defaultContents;
}
}
and then the razor page:
section test {
#this.RenderSection("extra", new HtmlString("<span>this is the default!</span>"));
}
Related
I want to open a pop up window using xamarin comunity toolkit extensions but when i try to call
Navigation it says that it does not exist even if i have included xct.extensions. There is NavigationExtensions but I don't know what I'm supposed to pass as first parameter and it says that my FilterPopup is of incorect type
using Xamarin.CommunityToolkit.Extensions;
namespace Appointments.ViewModels
{
public class WallViewModel
{
public ObservableCollection<Stylist> Stylists { get; set; }
public AsyncCommand OpenModalFiltersComand;
public WallViewModel()
{
OpenModalFiltersComand = new AsyncCommand(OpenModalFilters);
}
async Task OpenModalFilters()
{
NavigationExtensions.ShowPopup(AppShell, FilterPopup);
Navigation // error
}
}
}
My FilterPopup
namespace Appointments.Popups
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class FilterPopup : Popup
{
public FilterPopup()
{
InitializeComponent();
}
}
}
EDIT---------
I'm using shell navigation
ShowPopup takes an INavigation and an instance of a PopupBase. Navigation is a property of Page types, so your VM does not have a reference to it.
var nav = App.Current.MainPage.Navigation;
var filter = new FilterPopup();
NavigationExtensions.ShowPopup(nav, filter);
I want to create and AMP version of my website in ASP.NET MVC using .NET Core 2.0. Previously I had done some work with DisplayModeProvider instances in tha past on .Net framework, but that does not seem to be an option in .NET Core.
What I want to be able to do is alter the view names to be index.amp.cshtml rather than index.cshtml when my URL starts iwth /amp. What's the best way to achieve this in .NET Core?
You can do something like this using IViewLocationExpander. As it happens, I was playing with this a few days ago so I have some code samples to hand. If you create something like this:
public class AmpViewLocationExpander : IViewLocationExpander
{
public void PopulateValues(ViewLocationExpanderContext context)
{
var contains = context.ActionContext.HttpContext.Request.Query.ContainsKey("amp");
context.Values.Add("AmpKey", contains.ToString());
var containsStem = context.ActionContext.HttpContext.Request.Path.StartsWithSegments("/amp");
context.Values.Add("AmpStem", containsStem.ToString());
}
public IEnumerable<string> ExpandViewLocations(ViewLocationExpanderContext context, IEnumerable<string> viewLocations)
{
if (!(context.ActionContext.ActionDescriptor is ControllerActionDescriptor descriptor)) { return viewLocations; }
if (context.ActionContext.HttpContext.Request.Query.ContainsKey("amp")
|| context.ActionContext.HttpContext.Request.Path.StartsWithSegments("/amp")
)
{
return viewLocations.Select(x => x.Replace("{0}", "{0}.amp"));
}
return viewLocations;
}
}
iViewLocationExpander can be found in Microsoft.AspNetCore.Mvc.Razor
Then in your Configure Services method in Startup.cs, add the following:
services.Configure<RazorViewEngineOptions>(options =>
{
options.ViewLocationExpanders.Add(new AmpViewLocationExtender());
});
What this will do is update the view locations per request to insert .amp before .cshtml any time the URL either starts with /amp or there is a query string key of amp. If your AMP views don't exist, it might blow-up a little, I've not fully tested it, but it should get you started.
You can define this Middleware :
public class AmpMiddleware
{
private RequestDelegate _next;
public AmpMiddleware(RequestDelegate next)
{
_next = next;
}
public Task Invoke(HttpContext context)
{
const string ampTag = "/amp";
var path = context.Request.Path;
if (path.HasValue)
{
var ampPos = path.Value.IndexOf(ampTag);
if (ampPos >= 0)
{
context.Request.Path = new PathString(path.Value.Remove(ampPos, ampTag.Length));
context.Items.Add("amp", "true");
}
}
return _next(context);
}
}
public static class BuilderExtensions
{
public static IApplicationBuilder UseAmpMiddleware(this IApplicationBuilder app)
{
return app.UseMiddleware<AmpMiddleware>();
}
}
And call it in Startup:
app.UseAmpMiddleware();
Then can check in page and simple set another layout or limit some code, in his way no need to create separate page for amp version:
#if (HttpContext.Items.ContainsKey("amp"))
{
<b>Request AMP Version</b>
}
I am trying to have a general home page that depending on the parameter passed to the control, different content (modules) will be displayed.
For example, a user may select Kentucky from the menu and the id for Kentucky is 1. The home controller gets the id (1) and determines the possible modules for that
state (a simple db call.) Perhaps there is an announcements module and a contacts module for the state. An announcements module could have several items but it's only one module. There would be a partial view for each type of module.
Here is the basic setup I have.
public interface IModuleRepository
{
IList<MenuItemModule> GetMenuItemModules(int menuItem);
IList<Announcements> GetAnnouncements(int modID);
IList<News> GetNews(int modID);
IList<Contacts> GetContacts(int modID);
}
//business object
public class MenuItemModule
{
private int _MenuItemID;
private int _ModuleID;
private int _ModuleDefID;
private string _Src;
private int _ModuleOrder;
//get, set properties for these...
}
//announcements entity
public class Announcements
{
private int _ID = -1;
private int _MenuItemID = -1;
private int _ModuleID = -1;
private string _Description = string.Empty;
//get set props ...
}
In my home controller...
public class HomeController : Controller
{
private IModuleRepository modRepository;
public HomeController(IModuleRepository modRepository)
{
this.modRepository = modRepository;
}
public ViewResult Item(string ItemID)
{
//returns a list of menuitemmodules for the page. This gives me the Src or name of each
//module on the page, i.e. Announcements, news, contacts, etc.
var modules = modRepository.GetMenuItemModules(Convert.ToInt32(ItemID));
return View(modules);
}
}
I have tried several different models to return but I always run up against some contstraint. If I pass the menuitemmodules to my Item.aspx, then I can do something like this:
foreach (var mod in Model)
{
Html.RenderPartial(mod.Src, a); //needs an announcement object though
}
That makes it somewhat dynamic because I have the Src which would basically be something like "Announcements" and I can just create an announcements.ascx partial to process the module. But I have found it difficult to pass my menuitemmodule and an announcements entity as well.
I have also messed around with passing a more complex object and then testing every Src that comes through with an If statement. This would make scaling difficult in the future as I increase the number of possible modules in the app.
How can I solve my problem? I hope I have provided enough info. I like the basic idea here - http://www.mikesdotnetting.com/Article/105/ASP.NET-MVC-Partial-Views-and-Strongly-Typed-Custom-ViewModels but that seems to only work for static modules on a page.
I did try a composite view model called ModuleViewModel. Here is that attempt:
public class ModuleViewModel
{
public IList<Announcements> announcements { get; set; }
public IList<MenuItemModule> mods { get; set; }
}
If I pass that model to the Item.aspx I can do something like this (but I must be doing something wrong because something doesn't look right.)
foreach (var mod in Model)
{
if (mod.announcements.Count > 0)
{
Html.RenderPartial("Announcements", mod.announcements);
}
}
Once again, scalability is going to haunt me. I would like to have something like this on item page:
foreach (var mod in Model)
{
Html.RenderPartial(mod.Src, mod);
}
That would the correct partial view and pass it the correct model.
Create Module classes that derive from a common Module base class:
public class AnnouncementsModule : Module
{
}
public class ContactsModule : Module
{
}
In controller:
Create your various modules and put them into your overall view module (here it has a property called Modules that is an array of Module:
var viewModel = new ComplexViewModel
{
Modules = new []
{
new ContactsModule(),
new AnnouncementsModule()
}
};
return View(viewModule);
In view:
#Html.DisplayFor(x => x.Modules);
Create the partial views for each Type of Module in the appropriate 'Shared` folder. (Run it without creating them and it will show you an exception with the locations where it's looking for them).
After messing around with this for over a week, I finally managed to figure out how MVC can do what I want dynamically. I decided to post my solution for others that are new to MVC. Hopefully, the following will clear up the misunderstandings I had (although, at this point in my understanding of MVC, I cannot say this is the best approach.)
I will include the previous code snips and modifications for clarity:
public interface IModuleRepository
{
IList<MenuItemModule> GetMenuItemModules(int menuItem);
IList<Announcements> GetAnnouncements(int modID);
IList<News> GetNews(int modID);
IList<Contacts> GetContacts(int modID);
}
//business object
public class MenuItemModule
{
private int _MenuItemID;
private int _ModuleID;
private int _ModuleDefID;
private string _Src;
private int _ModuleOrder;
//get, set properties for these...
}
//announcements entity
public class Announcements : MenuItemModule
{
private int _ID = -1;
private string _Description = string.Empty;
//get set props ...
}
I also added another class:
public class AnnouncementModule : MenuItemModule
{
private IList<Announcements> _Announcements;
//get set prop
}
...and I created a model for the view
public class HomeItemViewModel
{
public MenuItemModule[] MenuItemModules { get; set; } //collection of menuitemmodules
}
In my home controller...
var menuItemModules = modRepository.GetMenuItemModules(ItemID);
if (menuItemModules.Count > 0)
{
AnnouncementModule aMod;
MenuItemModule[] mods = new MenuItemModule[menuItemModules.Count()];
int i = 0;
//loop through each MenuItemModule assign to the appropriate model
foreach (MenuItemModule mod in menuItemModules)
{
if (mod.Src == "Announcements")
{
aMod = new AnnouncementModule();
aMod.Announcements = modRepository.GetAnnouncements(mod.ModuleID);
//now add this to the menuitemmodule collection
mods[i] = aMod;
}
if (mod.Src == "Contacts")
{
//...
}
i++;
}
}
var viewModel = new HomeItemViewModel
{
MenuItemModules = mods
};
return View(viewModel);
Then I used the suggestion to use DisplayFor in the view. The view is strongly typed to HomeItemViewModel.
<%: Html.DisplayFor(m => m.MenuItemModules) %>
This iterates through the collection and based on the type, it will call that template. In this example, it calls AnnouncementModule.ascx which is strongly typed to AnnouncementModule.
foreach (var a in Model.Announcements)
{
//a.Description will give us the description of the announcement
}
I realize there are slicker ways to code the controller, and I plan on refactoring, but this skeleton should provide the basics to solve the question I posted.
I have an ASP.NET MVC 3 application that uses custom attributes to create select controls for model properties that can be populated from external data sources at runtime. The issue is that my EditorTemplate output appear to be cached at the application level, so my drop down lists are not updated when their data source changes until the Application Pool is recycled.
I also have output the contents of the MVC 3 ActionCache that is bound to the ViewContext.HttpContext object as shown in the MVC 3 source code in System.Web.Mvc.Html.TemplateHelpers.cs:95.
Action Cache GUID: adf284af-01f1-46c8-ba15-ca2387aaa8c4:
Action Cache Collection Type: System.Collections.Generic.Dictionary``2[System.String,System.Web.Mvc.Html.TemplateHelpers+ActionCacheItem]
Action Cache Dictionary Keys: EditorTemplates/Select
So it appears that the Select editor template is definitely being cached, which would result in the TemplateHelper.ExecuteTemplate method to always return the cached value instead of calling ViewEngineResult.View.Render a second time.
Is there any way to clear the MVC ActionCache or otherwise force the Razor view engine to always re-render certain templates?
For reference, Here are the relevant framework components:
public interface ISelectProvider
{
IEnumerable<SelectListItem> GetSelectList();
}
public class SelectAttribute : Attribute, IMetadataAware
{
private readonly ISelectProvider _provider;
public SelectAttribute(Type type)
{
_provider = DependencyResolver.Current.GetService(type) as ISelectProvider;
}
public void OnMetadataCreated(ModelMetadata modelMetadata)
{
modelMetadata.TemplateHint = "Select";
modelMetadata.AdditionalValues.Add("SelectListItems", SelectList);
}
public IEnumerable<SelectListItem> SelectList
{
get
{
return _provider.GetSelectList();
}
}
}
Next, there is a custom editor template in ~\Views\Shared\EditorTemplates\Select.cshtml.
#model object
#{
var selectList = (IEnumerable<SelectListItem>)ViewData.ModelMetadata.AdditionalValues["SelectListItems"];
foreach (var item in selectList)
{
item.Selected = (item != null && Model != null && item.Value.ToString() == Model.ToString());
}
}
#Html.DropDownListFor(s => s, selectList)
Finally, I have a view model, select provider class and a simple view.
/** Providers/MySelectProvider.cs **/
public class MySelectProvider : ISelectProvider
{
public IEnumerable<SelectListItem> GetSelectList()
{
foreach (var item in System.IO.File.ReadAllLines(#"C:\Test.txt"))
{
yield return new SelectListItem() { Text = item, Value = item };
}
}
}
/** Models/ViewModel.cs **/
public class ViewModel
{
[Select(typeof(MySelectProvider))]
public string MyProperty { get; set; }
}
/** Views/Controller/MyView.cshtml **/
#model ViewModel
#using (Html.BeginForm())
{
#Html.EditorForModel()
<input type="submit" value="Submit" />
}
** EDIT **
Based on suggestions in the comment, I started to look more closely at the ObjectContext lifecycle. While there were some minor issues, the issue appears to be isolated to an odd behavior involving a callback within a LINQ expression in the SelectProvider implementation.
Here is the relevant code.
public abstract class SelectProvider<R, T> : ISelectProvider
where R : class, IQueryableRepository<T>
{
protected readonly R repository;
public SelectProvider(R repository)
{
this.repository = repository;
}
public virtual IEnumerable<SelectListItem> GetSelectList(Func<T, SelectListItem> func, Func<T, bool> predicate)
{
var ret = new List<SelectListItem>();
foreach (T entity in repository.Table.Where(predicate).ToList())
{
ret.Add(func(entity));
}
return ret;
}
public abstract IEnumerable<SelectListItem> GetSelectList();
}
public class PrinterSelectProvider : SelectProvider<IMyRepository, MyEntityItem>
{
public PrinterSelectProvider()
: base(DependencyResolver.Current.GetService<IMyRepository>())
{
}
public override IEnumerable<SelectListItem> GetSelectList()
{
// Create a sorted list of items (this returns stale data)
var allItems = GetSelectList(
x => new SelectListItem()
{
Text = x.DisplayName,
Value = x.Id.ToString()
},
x => x.Enabled
).OrderBy(x => x.Text);
// Do the same query, but without the callback
var otherItems = repository.Table.Where(x => x.Enabled).ToList().Select(x => new SelectListItem()
{
Text = x.DisplayName,
Value = x.Id.ToString()
}).OrderBy(x => x.Text);
System.Diagnostics.Trace.WriteLine(string.Format("Query 1: {0} items", allItems.Count()));
System.Diagnostics.Trace.WriteLine(string.Format("Query 2: {0} items", otherItems.Count()));
return allItems;
}
}
And, the captured output from the System.Diagnostics.Trace is
Query 1: 2 items
Query 2: 3 items
I'm not sure what could be going wrong here. I considered that the Select may need an Expressions, but I just double-checked and the LINQ Select method only takes Func objects.
Any additional suggetions?
Problem Solved!
I finally had a chance to re-visit this issue. The root cause had nothing to do with LINQ, the ActionCache, or the ObjectContext, rather it was related to when attribute constructors are called.
As shown, my custom SelectAttribute class calls DependencyResolver.Current.GetService in its constructor to create an instance of the ISelectProvider class. However, the ASP.NET MVC framework scans the assemblies for custom metadata attributes once and keeps a reference to them in the application scope. As explained in the linked question, accessing a Attribute triggers its constructor.
So, the constructor was run only once, rather than on each request, as I had assumed. This meant that there was actually only one, cached instance of the PrinterSelectProvider class instantiated that was shared across all requests.
I solved the problem by changing the SelectAttribute class like this:
public class SelectAttribute : Attribute, IMetadataAware
{
private readonly Type type;
public SelectAttribute(Type type)
{
this.type = type;
}
public void OnMetadataCreated(ModelMetadata metadata)
{
// Instantiate the select provider on-demand
ISelectProvider provider = DependencyResolver.Current.GetService(type) as ISelectProvider;
modelMetadata.TemplateHint = "Select";
modelMetadata.AdditionalValues.Add("SelectListItems", provider.GetSelectList());
}
}
Tricky problem indeed!
I used an example on extensible asp.net mvc 3 to build my plug-able application, but I encountered a problem. In a plug-in I declared and implmemented an interface.
But, in plug-in controller when I want to use this class, the application throws an error and it seems that EntityConfig was not initialized. How can this be fixed?
[Export(typeof(IController)), ExportMetadata("controllerName", "Concept")]
[PartCreationPolicy(CreationPolicy.NonShared)]
public class ConceptController : Controller
{
[Import(typeof(IEntityConfig))]
private IEntityConfig EntityConfig;
public ActionResult Index()
{
var obs = EntityConfig.EntityName;
return View("~/Bin/Views/Concept/Index.cshtml",obs );
}
}
public interface IEntityConfig
{
string EntityName { get;}
}
[Export(typeof(IEntityConfig))]
public class TestEntity : IEntityConfig
{
public string EntityName
{
get{return "Test";}
}
}
Edited :
In other side, when I is use this example, there is no problem in resolving EntityConfig, but in the view, when I want to load model as follows :
#using Concepts
#model Concepts.Models.TestModel
the application throws an error and tells me 'The type or namespace name 'Concepts' could not be found', although when I check container after it was initiated, I can see Concepts in in loaded assemblies.
Would you please help me ?
Thanks.
Edited :
I uploaded the samples :
First one
Second one
Edited (2011/22/09):
I tested the above code on other sample that #Matthew Abbott provided in his blog, and it worked, although this sample has been built against mvc 2.0.
Looking over your code, can you be sure that the part is actually being imported? Your constructor code for your composition container is such like:
var discoverableControllerFactory = new DiscoverableControllerFactory(
new CompositionContainer(
new DirectoryCatalog(extensionsPath))
);
You're only including your extensions path as a catalog. Can you guaruntee that you're also including your base application path, e.g.:
var discoverableControllerFactory = new DiscoverableControllerFactory(
new CompositionContainer(
new AggregateCatalog(
new DirectoryCatalog("bin"),
new DirectoryCatalog(extensionsPath)))
);
If the parts actually exist in your Unity container, you could add an export provider that grabs those parts from that container and allows them to be composed by MEF.
As for your second problem, you will need to subclass the System.Web.WebPages.Razor.RazorBuildProvider to ensure it includes assemblies in your extensions directory:
namespace ExtensibleMvcApplication
{
public class CustomRazorBuildProvider : RazorBuildProvider
{
public static IEnumerable<Assembly> _assemblies;
static CustomRazorBuildProvider()
{
string extensionsPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Extensions");
_assemblies = Directory.GetFiles(extensionsPath, "*.dll")
.Select(Assembly.Load);
}
public override void GenerateCode(System.Web.Compilation.AssemblyBuilder assemblyBuilder)
{
foreach (var assembly in _assemblies)
assemblyBuilder.AddAssemblyReference(assembly);
base.GenerateCode(assemblyBuilder);
}
}
}
Which you'd need to register in your config:
<buildProviders>
<remove extension=".cshtml" />
<add extension=".cshtml" type="ExtensibleMvcApplication.CustomRazorBuildProvider, ExtensibleMvcApplication"/>
</buildProviders>