Question

How come I get an invalid cast exception when trying to set a NULL value returned from the database inside Comments which is of type Int32.

I am trying to replace this:

                try
                {
                    objStreamItem.Comments = (Int32)sqlReader["Comments"];
                    if (objStreamItem.Comments > 0) { 
                        listComments = Comment.GetAll(objStreamItem.Id);

                    }
                }
                catch (InvalidCastException)
                {
                    // Execute if "Comments" returns NULL
                    listComments = null;
                    objStreamItem.Comments = 0;
                }

With this:

Comments = ((Int32?)sqlReader["Comments"]) ?? 0

The two are in different contexts, but you should get the idea. Instead of using a try catch block I am trying to solve this in a more elegant way.

Thanks.

UPDATE

It is stored as a nullable integer in the database.

    public int? Comments
    {
        get;
        set;
    }

I just want to thank everyone who answered or posted on this question, everything was very informative. thanks!

Answer 1

I suppose a ternary expression is the way to go here

objStreamItem.Comments = sqlReader["Comments"] is DBNull ? 0 : (Int32)sqlReader["Comments"] ;

You could also store the return value of sqlReader["Comments"] in a variable first to shorten the expression

var comments = sqlReader["Comments"];
objStreamItem.Comments = comments is DBNull ? 0 : (Int32)comments;