Question

I’ve coded a class which uses connection to the WebMatrix database. I can greatly do insert, update queries, but I have an issue with select queries.
I can’t assign the Razor dynamic variable to my type-specified variable.

How to use the WebMatrix database in an usual c# class?

My code from the class:

    public bool verify_session()
    {
        if (get_user_id() > 0)
    {
        return true;
    }

        if (HttpContext.Current.Request.Cookies["session_id"] != null)
    {
        var db = Database.Open("studia_sesje");
        var data = db.QuerySingle("SELECT session_id, user_id FROM sessions WHERE session_id = '" + HttpContext.Current.Request.Cookies["session_id"] + "'");

        _session_id = (string)data.session_id;
        _user_id = (int)data.user_id;

        return true;
    }

    return false;
    }

the error is

Cannot perform runtime binding on a null reference

Answer 1

The error says that the result of your QuerySingle method call was null, or no rows in your database were returned. You should check the data is not null before trying to access dynamic properties:

var session_id = HttpContext.Current.Request.Cookies["session_id"];
var sql = "Select session_id, user_id From Sessions Where session_id = @0";
var data = db.QuerySingle(sql, session_id);
if(data != null){
    _session_id = data.session_id; //bit pointless, you already have that value
    _user_id = data.user_id; // no need to cast to int
    return true;
}
return false;