Session variables in ASP.NET MVC

Question

I am writing a web application that will allow a user to browse to multiple web pages within the website making certain requests. All information that the user inputs will be stored in an object that I created. The problem is that I need this object to be accessed from any part of the website and I don't really know the best way to accomplish this. I know that one solution is to use session variables but I don't know how to use them in asp .net MVC. And where would I declare a session variable? Is there any other way?

Answer 1

The answer here is correct, I however struggled to implement it in an ASP.NET MVC 3 app. I wanted to access a Session object in a controller and couldn't figure out why I kept on getting a "Instance not set to an instance of an Object error". What I noticed is that in a controller when I tried to access the session by doing the following, I kept on getting that error. This is due to the fact that this.HttpContext is part of the Controller object.

this.Session["blah"]
// or
this.HttpContext.Session["blah"]

However, what I wanted was the HttpContext that's part of the System.Web namespace because this is the one the Answer above suggests to use in Global.asax.cs. So I had to explicitly do the following:

System.Web.HttpContext.Current.Session["blah"]

this helped me, not sure if I did anything that isn't M.O. around here, but I hope it helps someone!

Answer 2

Well, IMHO..

1. never reference a Session inside your view/master page
2. minimize your useage of Session. MVC provides TempData obj for this, which is basically a Session that lives for a single trip to the server.

With regards to #1, I have a strongly typed Master View which has a property to access whatever the Session object represents....in my instance the stongly typed Master View is generic which gives me some flexibility with regards to strongly typed View Pages

ViewMasterPage<AdminViewModel>

AdminViewModel
{
    SomeImportantObjectThatWasInSession ImportantObject
}

AdminViewModel<TModel> : AdminViewModel where TModel : class
{
   TModel Content
}

and then...

ViewPage<AdminViewModel<U>>

Answer 3

There are 3 ways to do it.

1. You can directly access HttpContext.Current.Session

2. You can Mock HttpContextBase

3. Create a extension method for HttpContextBase

I prefer 3rd way.This link is good reference.

Get/Set HttpContext Session Methods in BaseController vs Mocking HttpContextBase to create Get/Set methods

Answer 4

If you are using asp.net mvc, here is a simple way to access the session.

From a Controller:

{Controller}.ControllerContext.HttpContext.Session["{name}"]

From a View:

<%=Session["{name}"] %>

This is definitely not the best way to access your session variables, but it is a direct route. So use it with caution (preferably during rapid prototyping), and use a Wrapper/Container and OnSessionStart when it becomes appropriate.

HTH