[asp.net-mvc] How to use sessions in an ASP.NET MVC 4 application?

I am new to ASP.NET MVC. I have used PHP before and it was easy to create a session and select user records based on the current session variables.

I have looked everywhere on the Internet for a simple step-by-step tutorial that can show me how to create and use sessions in my C# ASP.NET MVC 4 application. I want to create a session with user variables that I can access from anywhere in my controllers and be able to use the variables in my LINQ queries.

You can store any kind of data in a session using:

Session["VariableName"]=value;

This variable will last 20 mins or so.

Due to the stateless nature of the web, sessions are also an extremely useful way of persisting objects across requests by serialising them and storing them in a session.

A perfect use case of this could be if you need to access regular information across your application, to save additional database calls on each request, this data can be stored in an object and unserialised on each request, like so:

Our reusable, serializable object:

[Serializable]
public class UserProfileSessionData
{
    public int UserId { get; set; }

    public string EmailAddress { get; set; }

    public string FullName { get; set; }
}

Use case:

public class LoginController : Controller {

    [HttpPost]
    public ActionResult Login(LoginModel model)
    {
        if (ModelState.IsValid)
        {
            var profileData = new UserProfileSessionData {
                UserId = model.UserId,
                EmailAddress = model.EmailAddress,
                FullName = model.FullName
            }

            this.Session["UserProfile"] = profileData;
        }
    }

    public ActionResult LoggedInStatusMessage()
    {
        var profileData = this.Session["UserProfile"] as UserProfileSessionData;

        /* From here you could output profileData.FullName to a view and
        save yourself unnecessary database calls */
    }

}

Once this object has been serialised, we can use it across all controllers without needing to create it or query the database for the data contained within it again.

Inject your session object using Dependency Injection

In a ideal world you would 'program to an interface, not implementation' and inject your serializable session object into your controller using your Inversion of Control container of choice, like so (this example uses StructureMap as it's the one I'm most familiar with).

public class WebsiteRegistry : Registry
{
    public WebsiteRegistry()
    {
        this.For<IUserProfileSessionData>().HybridHttpOrThreadLocalScoped().Use(() => GetUserProfileFromSession());   
    }

    public static IUserProfileSessionData GetUserProfileFromSession()
    {
        var session = HttpContext.Current.Session;
        if (session["UserProfile"] != null)
        {
            return session["UserProfile"] as IUserProfileSessionData;
        }

        /* Create new empty session object */
        session["UserProfile"] = new UserProfileSessionData();

        return session["UserProfile"] as IUserProfileSessionData;
    }
}

You would then register this in your Global.asax.cs file.

For those that aren't familiar with injecting session objects, you can find a more in-depth blog post about the subject here.

A word of warning:

It's worth noting that sessions should be kept to a minimum, large sessions can start to cause performance issues.

It's also recommended to not store any sensitive data in them (passwords, etc).

U can store any value in session like Session["FirstName"] = FirstNameTextBox.Text; but i will suggest u to take as static field in model assign value to it and u can access that field value any where in application. U don't need session. session should be avoided.

public class Employee
{
   public int UserId { get; set; }
   public string EmailAddress { get; set; }
   public static string FullName { get; set; }
}

on controller - Employee.FullName = "ABC"; Now u can access this full Name anywhere in application.

This is how session state works in ASP.NET and ASP.NET MVC:

ASP.NET Session State Overview

Basically, you do this to store a value in the Session object:

Session["FirstName"] = FirstNameTextBox.Text;

To retrieve the value:

var firstName = Session["FirstName"];