ViewState Throws System.Web.HttpUnhandledException When Is Initialized

Question

When I try to initialize ViewState key with value of type Group class it throws the following exception:

exception: Exception of type 'System.Web.HttpUnhandledException' was thrown.Error serializing value 'MMS.Classes.DBEntities.Group' of type 'MMS.Cl.Entities.Group.'

code:

protected void Page_PreRender(object sender, EventArgs e)
        {
            Controls();
        }

        private void Controls()
        {
            if (!Page.IsPostBack)
            {
                ViewState["Group"] = new Group();
                ViewState["Group"] = new List<string>(); // if I use this line instead the above it works works
            }
        }

What do you mean ? Group is a class which I created. – theChampion Mar 27 '14 at 09:49 — theChampion, Mar 27 '14 at 09:49

score 4 · Accepted Answer · answered Mar 27 '14 at 09:50

4

I think simply marking your Group class as serializable would make your code work, as the ViewState needs the class to be serializable to store it. For details about serialization you can visit this link. Add [Serializable] attribute to your class as following:

[Serializable]
public class Group
{
//properties
}

Hope this helps.

answered Mar 27 '14 at 09:50

Shashank Chaturvedi

2,756
19
29

Now it works fine. What [Serializable] did for this class to make it work? – theChampion Mar 27 '14 at 09:55
1

The answer to your question lies in understanding what serialization does. A serializable object can be transformed to any stream of data. Complex/Unmanaged objects/components can not be stored in ViewState. So ViewState need to know before hand that the Class that is being attempted to store is Serializable or not, marking class Serializable does that. – Shashank Chaturvedi Mar 27 '14 at 10:00

score 2 · Answer 2 · edited May 23 '17 at 11:49

2

since the result of storing items in ViewState is that those are stored in string on page (to maintain state between multiple requests), they need to be serializable, on the other hand Session is in memory storage (if you're using InProc mode, which is default, otherwise this doesn't apply), so objects don't need to be serializable.

Refer to this for more details:

Why Viewstate can contain only serializable object?

Updated:

You can find more information about Serialization here:

http://msdn.microsoft.com/en-us/library/ms233843.aspx

Hope this helps .

edited May 23 '17 at 11:49

Community

1
1

answered Mar 27 '14 at 09:56

Sai Avinash

4,683
17
58
96

1

Nice point (voted one up) if you are planning to use the class across multiple pages then you can store it in session, but if its page specific usage then you should continue to use the ViewState by simply marking your class Serializable (that has no side affects :) ). – Shashank Chaturvedi Mar 27 '14 at 10:10

ViewState Throws System.Web.HttpUnhandledException When Is Initialized

2 Answers2