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Make sure HttpContext.Current is valid and available

Posted on 2008-06-17
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Last Modified: 2010-04-21
Morning,

I have a class that handles my sessions that have been created, i access this class to get or set the session. I do these so that i can easily mange all the session on my site from one class and then access the class to get  the session values.

A typical property of the class would be something like this:

        public int CustomerID
        {
            get
            {
                intCustomerID = Convert.ToInt32(HttpContext.Current.Session["CustomerID"].ToString());
                return intCustomerID;
            }
            set
            {
                intCustomerID = value;
                HttpContext.Current.Session["CustomerID"] = intCustomerID.ToString();
            }
        }

This was producing some errors in my logs "Parameter is not valid" because it seems that the class trying to get the Session["CustomerID"] was using it to insert into the database but i suspect that HttpContext.Current was null or is not available. In this case i would in addition get the error "Object reference not set to an instance of an object." because Session["CustomerID"] could not be accessed...

this could sometime be the case with these sessions and sometimes HttpContex may not be available for the class calling this property. So i modified the method like so:

        public int CustomerID
        {
            get
            {
                if (!Int32.TryParse(HttpContext.Current.Session["CustomerID"].ToString(), out intCustomerID))
                {
                    intCustomerID = -1;
                }

                return intCustomerID;
            }
            set
            {
                intCustomerID = value;
                HttpContext.Current.Session["CustomerID"] = intCustomerID.ToString();
            }
        }

Just to try and catch it it was available or not... As you can see this does not work and i get the same results...

So question is how do i check if HttpContext.Current is available or not and if not return a -1 value... I can't check if the session is null cause HttpContext.Current.Session is not available...

Hope that all made sense. Any ideas?

Nugs
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Comment
Question by:Nugs
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6 Comments
 
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Accepted Solution

by:
crisco96 earned 500 total points
ID: 21806333
Just see if Current and Session are null
if(HttpContext.Current == null || HttpContext.Current.Session == null)
{
    return -1;
}

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Author Comment

by:Nugs
ID: 21806372
Next question... is there a way (some code) that i can use in testing that will force HttpContext.Current to become null... I can't seem to reproduce these errors locally and only see them in my logs... Well actually the lack of logs as this is what seems to be failing....

Nugs
0
 
LVL 15

Expert Comment

by:crisco96
ID: 21806550
There isn't any code I can think of.  The only way Current or Session should be null is if you're calling the property too early in the page life cycle (perhaps the constructor, not sure) or if the property is part of a shared library that won't necessarily have a web user requesting access.
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LVL 2

Author Comment

by:Nugs
ID: 21806562
So then something like this should work?
        public int CustomerID
        {
            get
            {
                if (HttpContext.Current == null || HttpContext.Current.Session == null)
                {
                    intCustomerID = -1;
                }
                else
                {
                    if (!Int32.TryParse(HttpContext.Current.Session["CustomerID"].ToString(), out intCustomerID))
                    {
                        intCustomerID = -1;
                    }
                }
 
                return intCustomerID;
            }
            set
            {
                intCustomerID = value;
                HttpContext.Current.Session["CustomerID"] = intCustomerID.ToString();
            }
        }

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0
 
LVL 2

Author Comment

by:Nugs
ID: 21806580
Honestly i am not sure why it is not accessable... It could be that some classes calling this may not have web user requesting access. Either way i need to catch this at any point so that the inserts into the DB don't fail because of it...

Nugs
0
 
LVL 2

Author Closing Comment

by:Nugs
ID: 31468101
Think this will do it... Will have to check it in production though... Thanks!
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