Question

I have a table named Orders that has a column named OrderCode that stores a string that I randomly generate at the time of creation.

I want to make sure this string (OrderCode) is unique before I save it to my table.

How I have attempted to do this:

        bool isUnique = false;
        var order = new Order();
        var code = RandomCode.Generate();
        while (isUnique == false) // checks to see if the code we generated is unique among all generated codes, if not, will generate another code
        {
            var activeOrders = storeDB.Orders.Find("OrderCode", code);
            if (activeOrders == null)
            {
                isUnique = true;
            }
            else
            {
                code = RandomCode.Generate();
            }
        }

        order.OrderCode = code;

The problem appears to be that the DbSet<TEntity>.Find Method is actually used to search through primary keys – but I am needing to search for a string that is not a primary key.

What is a correct approach to this situation?

Answer 1

if (context.Orders.Any(o => o.OrderCode == code))
{
  // key found
}

if (context.Orders.FirstOrDefault(o => o.OrderCode == code) != null)
{
  // key found
}

May I ask why you don’t just use a System.Guid though (Guid.NewGuid().ToString())? This would virtually eliminate this kind of issue.