Session variables in ASP.NET MVC

Question

Hi,

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

I would think you'll want to think about if things really belong in a session state. This is something I find myself doing every now and then and it's a nice strongly typed approach to the whole thing but you should be careful when putting things in the session context. Not everything should be there just because it belongs to some user.

in global.asax hook the OnSessionStart event

void OnSessionStart(...)
{
    HttpContext.Current.Session.Add("__MySessionObject", new MySessionObject());
}

From anywhere in code where the HttpContext.Current property != null you can retrive that object. I do this with an extension method.

public static GetMySessionObject(this HttpContext current)
{
    return current != null ? current.Session["__MySessionObject"] : null;
}

This way you can in code

void OnLoad(...)
{
    var sessionObj = HttpContext.Current.GetMySessionObject();
    // do something with 'sessionObj'
}

Answer 2

Although I don't know about asp.net mvc, but this is what we should do in a normal .net website. It should work for asp.net mvc also.

YourSessionClass obj=Session["key"] as YourSessionClass;
if(obj==null){
obj=new YourSessionClass();
Session["key"]=obj;
}

You would put this inside a method for easy access. HTH

Answer 3

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 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