I need to populate an element from the Database, first thing when I compile/run my MVC3 application.
I have a static class and static method to populate the element. I just need to know how I could somehow call the method at the startup of my application.
Here's the code:
public static class Select_Brands
{
public static IQueryable<Brand> BrandsQ { get; set; }
public static IQueryable<Brand> GetBrands()
{
using (Online_Store_DBEntities EFModel = new Online_Store_DBEntities())
{
BrandsQ = EFModel.Brands;
}
return BrandsQ;
}
}
Is there any way ?
In every MVC Application you have a Global.asax like in an ASP.NET Application and you can run code in Application_Start() Method.
But you should think about where to persist the data and what you really use this for.
There is a method in the global.asax file called Application_Start - sounds like this could be a candidate for what you want.
Related
Entity Framework 4, Ninject 3, MVC3
Currently in my web app i have been using a rather rudimentary approach to per request instantiation of an Object Context. So I am experimenting with Ninject, and some old sample code, but I am unsure how to proceed with the following..
Effectively I want to be able in the controller to do the equivalent of: DB_Entities.Current.Albums ... Should i be instantiating a StandardKernel every time?
The sample i was looking at was using the following: MvcApplication.Container.Get(); but in Ninject 3 with the App_Start hookup I dont have access to Container..
My attempt to replicate the above line, is failing at runtime.
using MusicStoreEntities;
using Ninject;
using TestMVC3WithIOC.App_Start;
using System.Data.Objects;
namespace TestMVC3WithIOC.Models
{
public partial class MusicStoreEntities
{
public static MusicStoreEntities Current
{
get
{
using (IKernel kernel = new StandardKernel())
{
return (MusicStoreEntities)kernel.Get<ObjectContext>();
}
}
}
}
}
Also, note, that in App_Start\NinjectWebCommon.cs I have the following modification:
private static void RegisterServices(IKernel kernel)
{
kernel.Bind<ILogger>().To<NLogger>();
kernel.Bind<ObjectContext>().To<MusicStoreEntities>().InRequestScope();
}
Although a workable solution, it seems ill-advised to pass the entire Kernel into a class, because it tends to obscure the classes actual, specific dependencies. A better approach is to pass a factory dependency into your controller's constructor.
public partial class MusicStoreEntities
{
private readonly IEntitiesFactory _factory;
public MusicStoreEntities(IEntitiesFactory factory)
{
_factory = factory;
}
}
IEntitiesFactory has a simple implementation with a single method GetObjectContext().
(I believe also the "Unit of Work" pattern is popular at the moment, but I can't really speak to that as I haven't used it. Maybe worth looking into.)
In order to support lazy loading feature in EF, what is the best way to instantiate DbContext?
I know HttpContext's current item is good place to create DbContext via Application_BeginRequest method and Application_EndRequest method, but in some sample codes of MSDN and official asp.net mvc site, they just create DbContext in Controller's constructor and dispose it in controller's Dispose() method.
I think the both ways are not too different because all of those all implement session per request pattern.
I just want to make sure that my understanding is correct or not.
The Dispose() method in the controller isn't always reliable. By the same token, Session is probably not a good idea either. "Best" is probably subjective, but we've had the best success by using dependency injection (Castle Windsor) and following a Unit of Work Repository pattern.
Setup the unit of work along the following lines:
public class UnitOfWork : IUnitOfWork
{
public UnitOfWork()
{
this.Context = new MyEFEntities();
this.Context.ContextOptions.LazyLoadingEnabled = true;
}
public void Dispose()
{
this.Context.Dispose();
}
public ObjectContext Context { get; internal set; }
}
Setup your repository:
public class Repository<TEntity> : IRepository<TEntity>
where TEntity : class
{
public Repository(IUnitOfWork unitOfWork)
{
Context = unitOfWork.Context;
ObjectSet = Context.CreateObjectSet<TEntity>();
}
public ObjectContext Context { get; set; }
public IObjectSet<TEntity> ObjectSet { get; set; }
}
Register with Castle in Global.asax:
void Application_Start()
{
this.Container.Register(
Component.For<IUnitOfWork>()
.UsingFactoryMethod(() => new UnitOfWork())
.LifeStyle
.Is(LifestyleType.PerWebRequest)
);
ControllerBuilder.Current.SetControllerFactory(
new WindsorControllerFactory(this.Container));
}
And use in your controller (or wherever you're using it, as long as it's injectable):
public class SomeController
{
public SomeController(IRepository<MyEntity> repository)
{
this.Repository = repository;
}
public IRepository<MyEntity> Repository { get; set; }
public ActionResult MyAction()
{
ViewData.Model = this.Repository.ObjectSet.Single(x => x.Condition); //or something...
}
}
Any lazy loading here could potentially be a trap for a future issue. Without DI, without a repository - its hard to see anything working without it being a hack for lazy loading. Also do you you plan on passing your entities to your view. If so this is going to create a bad overlap. The controller should package data for your view, not have things evaluated later in your view.
For MVC best practices, you should flatten out your domain model as much as possible into a viewmodel (if flattening makes sense) and use the view model. Since you would ideally then know what would be lazy loaded, it may make more sense to take the hit up front and use .Include() in your query to eager load, otherwise you can issue many many queries to the database.
I've used a session factory pattern and saved the DBContext in the session object. It will stay open per session. I haven't had problems with it so far.
I'm trying to inject a second repository into my asp.net mvc 3 controller. And I cant get it to work, not sure where to "add another" using Ninject.
I have a void function in global.asa.cs
kernel.Bind<INewsRepository>().To<NewsRepository>();
And in my controller I have:
private INewsRepository _newsRepository;
private IContentRepository _contentRepository;
public NewsController(INewsRepository newsRepository, IContentRepository contentRepository)
{
this._newsRepository = newsRepository;
this._contentRepository = contentRepository;
}
How can I register IContentRepository for the NewsController as well?
I use autofac instead of Ninject but the basics stay the same.
If you got your first dependency injection working then you should be able to bind others as well. You just have to add a new binding in Application_Start() in your Global.asax.
So under your first binding do this as well:
kernel.Bind<IContentRepository>().To<ContentRepository>();
You can have as many bindings as you like.
First off it's a good practice to move the bootstrapping of your application into a separate location. This keeps your Global.asax clean.
You should also be using convention based registration. It will end up saving you lots of time for the bindings you don't need to customize.
So for you I'd probably suggest the following
public static class Bootstrapper()
{
public static void Bootstrap()
{
kernel.Scan( k =>
{
k.FromAssemblyContaining<INewsRepository>();
k.BindWithDefaultConventions();
});
}
}
And in your Global.asax you add this..
Bootstrapper.Bootstrap();
Then I would suggest you spend some time on Google reading about ninject conventions.
I am creating an application in mvc3 and wondering how to deal with database data which is required for all application requests, some of them depends on a session, some of them depends on url pattern basically all data is in database.
Like to know best practice
What I do in my applications and consider to be the best practice is to load your common data to the ViewBag on the Controller constructor.
For every project, I have a DefaultController abstract class that extends Controller. So, every controller in the project must inherit from DefaultController, instead of Controller. In that class' constructor, I load all data common to the whole project, like so:
// DefaultController.cs
public abstract class DefaultController : Controller
{
protected IRepository Repo { get; private set; }
protected DefaultController(IRepository repo)
{
Repo = repo;
ViewBag.CurrentUser = GetLoggedInUser();
}
protected User GetLoggedInUser()
{
// your logic for retrieving the data here
}
}
// HomeController.cs
public class HomeController : DefaultController
{
public HomeController(IRepository repo) : base(repo)
{
}
// ... your action methods
}
That way you will always have the logged in user available in your views.
I do the same as #rdumont but with one exception: I create a CommonViewModel which I use to define all common properties that I use.
public class CommonViewModel
{
public string UserName {get;set;}
public string Extension {get;set; }
}
Declare a property in the base controller:
public abstract class BaseController : Controller
{
protected CommonViewModel Commons { get; private set; }
protected virtual void OnResultExecuting(ResultExecutingContext filterContext)
{
ViewBag.Commons = Commons;
}
}
By doing so I get everything almost typed. The only cast that I need to do is to cast ViewBag.Commons to the CommonViewModel.
Best is to avoid ViewBag at all.
See this answer, which details how to use Html.RenderAction() for that purpose:
Best way to show account information in layout file in MVC3
I'd suggest using a base ViewModel class.
So a base class with properties/functions which should be available at any point.
in the Global.asax file, I manage some threads, and - from the Controller - I need to invoke an event of the one's thread. Is it possible to have access to that thread ?
You could use the application state to store some object that will be shared among all users of the application:
protected void Application_Start()
{
Application["foo"] = "bar";
...
}
and inside your controller you can access this property:
public ActionResult Index()
{
var foo = HttpContext.Application["foo"] as string;
...
}
You could if it were any other kind of object, like a string, because you'll need to declare the property as static in the Global.asax to make it available to the rest of the app:
public class Application : HttpApplication
{
// This is the class declared in Global.asax
// Your route definitions and initializations are also in here
public static string MyProperty { get; set; }
}
This will be available to the rest of the application. You can call by doing:
public ActionResult MyAction()
{
var bla = Application.MyProperty;
}
That said, I dont think you want to make a Thread available to the rest of the app this way.