public static string AddAdmin(UsersEntities users, Users user)
{
using (var transaction = new TransactionScope())
{
users.Users.Add(user);
// Create the group Admins if it does not exits
var admins = users.Groups.Where(g => g.GroupName == "Admins").FirstOrDefault();
if (admins == null)
{
users.Groups.Add(new Groups() { GroupName = "Admins" });
users.SaveChanges();
}
user.Groups = users.Groups.Where(g => g.GroupName == "Admins").First();
try
{
users.SaveChanges();
}
// Adding a duplicate username violates the unique key constraint and should rollback the transaction
catch (DbUpdateException)
{
throw new InvalidOperationException(string.Format("The username {0} already exists in the database.", user.Username));
}
transaction.Complete();
}
return string.Format("{0} added as admin", user.Username);
}
public static void Main()
{
// To create the database, execute the script Users.sql in the program folder
using (var users = new UsersEntities())
{
try
{
Console.WriteLine(AddAdmin(users, new Users() { Username = "******" }));
}
catch (InvalidOperationException ex)
{
Console.WriteLine(ex.Message);
}
}
}