public override async Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
        {
            User user = new User();

            user.Username = context.UserName;
            user.Password = context.Password;
            UserDataContext _objContext = new UserDataContext();

            user = _objContext.GetUser(user);
            if (user != null)
            {
                var identity = new ClaimsIdentity(context.Options.AuthenticationType);
                identity.AddClaim(new Claim("Username", user.Username));
                identity.AddClaim(new Claim("Password", user.Password));
                identity.AddClaim(new Claim("ID", user.ID));
                identity.AddClaim(new Claim("LoggedOn", DateTime.Now.ToString()));
                context.Validated(identity);
            }
            else
            {
                context.SetError("Unauthorized", "The user name or password is incorrect");
                return;
            }
        }