Question

this is somewhat tricky to figure out I think, perhaps I am missing something.
I am a newbie trying to rig a database mapped via Linq-to-SQL to my server. There is a function called by clients which retrieves UserAccount from the database:

public static explicit operator Dictionary<byte, object>(UserAccount a)
    {
        Dictionary<byte, object>  d = new Dictionary<byte, object>();
        d.Add(0, a.AuthenticationDatas.Username);
        int charCount = a.Characters.Count;
        for (int i = 0; i < charCount; i++)
        {
            d.Add((byte)(i + 1), (Dictionary<byte, object>)a.Characters[i]);
        }
        return d;
    }

What this actually does is convert a UserAccount type to my server datatype of Dictionary. UserAccount itself is retrieved from database then converted via this function.

However when I run this function, I get InvalidCastException on line:

int charCount = a.Characters.Count;

Moreover, when VS breakpoints @ this line, I can wait a few seconds and proceed and the excpetion will be gone! It retrieves Characters.Count correctly after that.

Here is my Characters mapping:

[global::System.Data.Linq.Mapping.AssociationAttribute(Name="UserAccount_Character", Storage="_CharactersTBs", ThisKey="UID", OtherKey="UID")]
    public EntitySet<Character> Characters
    {
        get
        {
            return this._Characters;
        }
        set
        {
            this._Characters.Assign(value);
        }
    }

I believe whats happening is that request is somehow executed on another thread then the one that interacts with database, and it errors out before database can actually retrieve Characters table. I am not quite sure…

Does anyone know what the problem might be and how can I syncronize it (without adding some gimp delay)?

EDIT:

Ok I narrowed down the problem. It has nothing to do with different threads networking or what not… Its just me being stupid. Here is a simple databse query which throws InvalidCastException @ line int count = UA.Characters.Count;

static void Main(string[] args)
    {           

        IEnumerable<UserAccount> query = from p in PBZGdb.Instance.AuthenticationDatas
                                         where p.Username == "Misha" && p.Password == "123"
                                         select p.UserAccount;
        UserAccount UA = query.ElementAt(0);
        int count = UA.Characters.Count;
        Console.WriteLine(count);
        Console.ReadKey();
    }

(p.s.) UA is NOT null it indeed finds a correct instance of userAccount and it has 2 Characters. If I wait few seconds and try again exception goes away..
What am I doing wrong? This is the first time I really use a database in VS please help! 🙂

Answer 1

Hey just want anyone having the same problem know, I figured it out. What happened was I manualy renamed LINQ .dbml file when I added it to my project after it was geneerated by sqlmetal. And of course I did it inconsistently (it was renamed in designer but not in its .cs file). I just re-generated a new .dbml file with sqlmetal with a correct name this time and everything works like butter!

Thanks guys!