How do I use my Session variable in an if statement as an integer?

Question

I have a Session that stores an int. I usually do the following...

if(Session["test"] == null)

Now that I am comparing...

public ActionResult NumbersGame(int myNum)
{
if(Session["test"] != myNum)...

How do I do that?

Answer 1

(int)Session["test"] will fail if that session variable is either null or not a number. Use this instead...

var myNumber = Convert.ToInt32(Session["test"]);

myNumber will be 0 if 'test' is null or not a number

Answer 2

将其强制转换为int：

if ((int) Session["test"] != myNum) ...

Answer 3

Another way of checking and using the value stored in your Session() object involves using the TryParse feature.

int intTest;
if (int.TryParse(Session["test"].ToString(), out intTest))
{
   // intTest will have the value in Session["Test"] stored as an integer

}

I like it because it's compact and simple.

Answer 4

Simple overview of how I would do it:

It may solve other problems too:

First we define interface:

public interface ISessionWrapper
{
    int? SomeInteger { get; set; }
}

Then we make HttpContext implementation:

public class HttpContextSessionWrapper : ISessionWrapper
{
    private T GetFromSession<T>(string key)
    {
        return (T) HttpContext.Current.Session[key];
    }

    private void SetInSession(string key, object value)
    {
        HttpContext.Current.Session[key] = value;
    }

    public int? SomeInteger
    {
        get { return GetFromSession<int?>("SomeInteger"); }
        set { SetInSession("SomeInteger", value); }
    }
}

Then we define our base controller:

public class BaseController : Controller
{
    public ISessionWrapper SessionWrapper { get; set; }

    public BaseController()
    {
        SessionWrapper = new HttpContextSessionWrapper();
    }
}

Finally:

public ActionResult NumbersGame(int myNum)
{           
    if (SessionWrapper.SomeInteger == myNum)
        //Do what you want;
}

No need to cast here!! And if you wanted to test your controller, you have no problem with Session. You just Mock ISessionWrapper and pass it to SessionWrapper variable.

Answer 5

I would test for null (to detect Session expiry), then cast:

object value = Session["test"];
if (value == null)
{
    // The value is not in Session (e.g. because the session has expired)
    // Deal with this in an application-specific way, e.g. set to a default,
    // reload the Session variable from the database, redirect to a home page, ...
    ...
}
else
{
    myNumber = (int) value;
}
...

The problem with using Convert.ToInt32 is that it will simply return 0 if your session has expired, which may not be desirable depending on your application.