Question

When doing a Insert the variable id is returned as an object. However in my database it is an int and in my POCO it is an int however when the method call to ExecuteScalar to return @@IDENTITY is called it returns the number 7 as an object but the debugger thinks its a decimal.

Therefore when I do int newID = (int)db.Insert(...) it throws a

InvalidCastException

Is this a framework bug or a PetaPoco bug?

Answer 1

It’s going to depend on what RDBMS you are connecting to, which you didn’t state.

Here’s the relevant code from PetaPoco that retrieves the last id and returns it:

object id;
switch (_dbType)
{
    case DBType.SqlServerCE:
        DoPreExecute(cmd);
        cmd.ExecuteNonQuery();
        id = ExecuteScalar<object>("SELECT @@@IDENTITY AS NewID;");
        break;
    case DBType.SqlServer:
        cmd.CommandText += ";\nSELECT SCOPE_IDENTITY() AS NewID;";
        DoPreExecute(cmd);
        id = cmd.ExecuteScalar();
        break;
    case DBType.PostgreSQL:
        if (primaryKeyName != null)
        {
            cmd.CommandText += string.Format("returning {0} as NewID", EscapeSqlIdentifier(primaryKeyName));
            DoPreExecute(cmd);
            id = cmd.ExecuteScalar();
        }
        else
        {
            id = -1;
            DoPreExecute(cmd);
            cmd.ExecuteNonQuery();
        }
        break;
    case DBType.Oracle:
        if (primaryKeyName != null)
        {
            cmd.CommandText += string.Format(" returning {0} into :newid", EscapeSqlIdentifier(primaryKeyName));
            var param = cmd.CreateParameter();
            param.ParameterName = ":newid";
            param.Value = DBNull.Value;
            param.Direction = ParameterDirection.ReturnValue;
            param.DbType = DbType.Int64;
            cmd.Parameters.Add(param);
            DoPreExecute(cmd);
            cmd.ExecuteNonQuery();
            id = param.Value;
        }
        else
        {
            id = -1;
            DoPreExecute(cmd);
            cmd.ExecuteNonQuery();
        }
        break;
    default:
        cmd.CommandText += ";\nSELECT @@IDENTITY AS NewID;";
        DoPreExecute(cmd);
        id = cmd.ExecuteScalar();
        break;
}