Does ASP.NET MVC Have Application Variables

Does asp.net MVC have Application variables?

Yes, you can access Application variables from .NET MVC. Here's how:

System.Web.HttpContext.Current.Application.Lock();
System.Web.HttpContext.Current.Application["Name"] = "Value";
System.Web.HttpContext.Current.Application.UnLock();

MVC access application variable in controller

For example, in global.asax:

Application["AppVar"] = "hello";

In any controller method:

string appVar = HttpContext.Application["AppVar"] as string;

Update (7/2018):
If you need to access MVC global application data from a DLL library:

using System.Web;
....
if (HttpContext.Current != null && HttpContext.Current.Application != null)
    string appVar = HttpContext.Current.Application["AppVar"] as string;

It is safer to check HttpContext.Current.Application against null as well, because some fake httpcontext library (used in unit test projects) could have a valid context with null "Application".

what is application variable? How do i declare Application variables in ASP.NET MVC?

In global.asax file
first declare service in which you write linq syntax or your logic,

 private readonly ISystemConfigurationService _systemConfigurationService;

Then, create constructor

public MvcApplication()
    {
        _systemConfigurationService = new SystemConfigurationService();
    }

Get Model Data when app start

protected void Application_Start()
    {
        AreaRegistration.RegisterAllAreas();
        FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
        RouteConfig.RegisterRoutes(RouteTable.Routes);
        BundleConfig.RegisterBundles(BundleTable.Bundles);
        List<SystemConfigurationModel> systemConfigurationValue = General.MapList<System_Configuration , SystemConfigurationModel> (_systemConfigurationService.GetAllSystemConfigData());
        Application["SystemConfig"] = new List<SystemConfigurationModel>(systemConfigurationValue);
    }

In controller you have to do this,

List<SystemConfigurationModel> applicationState = HttpContext.Application["SystemConfig"] as List<SystemConfigurationModel>;
ViewBag.ContactEmail = applicationState.Find(x => x.Config_Key == "ContactMail").Value;

Then Pass it to view using view bag.

How do you access application variables in asp.net mvc 3 razor views?

Views are not supposed to pull data from somewhere. They are supposed to use data that was passed to them in form of a view model from the controller action. So if you need to use such data in a view the proper way to do it is to define a view model:

public class MyViewModel
{
    public string LicenseName { get; set; }
}

have your controller action populate it from wherever it needs to populate it (for better separation of concerns you might use a repository):

public ActionResult Index()
{
    var model = new MyViewModel
    {
        LicenseName = HttpContext.Application["LICENSE_NAME"] as string
    };
    return View(model);
}

and finally have your strongly typed view display this information to the user:

<div>@Model.LicenseName</div>

That's the correct MVC pattern and that's how it should be done.

Avoid views that pull data like pest, because today it's Application state, tomorrow it's a foreach loop, next week it's a LINQ query and in no time you end up writing SQL queries in your views.

ASP.NET MVC Application Variables?

You can store application-wide data in the ASP.NET Cache.

Add your item to the cache using the Cache.Insert method. Set the sliding expiration value to a TimeSpan of 5 minutes. Write a wrapper class for accessing the object in the cache. The wrapper class can provide a method to obtain the object from the cache. This method can check whether whether the item is in the cache and load it if it isn't.

For example:

public static class CacheHelper
{
    public static MyObject Get()
    {
        MyObject obj = HttpRuntime.Cache.Get("myobject") as MyObject;

        if (obj == null)
        {
            // Create the object to insert into the cache
            obj = CreateObjectByWhateverMeansNecessary();

            HttpRuntime.Cache.Insert("myobject", obj, null, DateTime.Now.AddMinutes(5), System.Web.Caching.Cache.NoSlidingExpiration);

        }
        return obj;
    }
}

Access Application object in ASP.Net MVC to store application wide variables

In a controller you should be able to do this:

this.HttpContext.Application["foo"] = "bar";

Global Variables MVC application

Yes, you can use session, which is global to the current user only:

HttpContext.Current.Session["Login"] = "John Doe";

However, you won't do that in global.asax because Session is a module that gets initialized at a very specific time (see this). As such, you most likely want to do it in the controller at an appropriate time:

public ActionResult Index()
{
   this.HttpContext.Session["Login"] = "X";
}

As an oversimplified example.

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