public void RecommendAFriend(int referrerId, NewAccount friendsAccountDetails)
{
Validate(friendsAccountDetails);
using (var transaction = new System.Transactions.TransactionScope())
{
try
{
var referrer = customerDirectory.Find(referrerId);
var friend = customerDirectory.Add(friendsAccountDetails);
referAFriendPolicy.Apply(referrer, friend);
transaction.Complete();
var msg = new CustomerRegisteredViaReferralPolicy
{
ReferrerId = referrerId,
FriendId = friend.Id
};
bus.Publish(msg);
}
catch (ReferralRejectedDueToLongTermOutstandingBalance)
{
var msg = new ReferralSignupRejected
{
ReferrerId = referrerId,
FriendEmail = friendsAccountDetails.Email,
Reason = "Referrer has long term outstanding balance"
};
bus.Publish(msg);
}
}
}
public void RecommendAFriend(int referrerId, NewAccount friend)
{
// validation, open transaction etc
var command = new RecommendAFriend
{
ReferrerId = referrerId,
Friend = friend
};
Task.Factory.StartNew(() => policy.Apply(command));
// close transaction - success and failure handled in handlers
}
private void Validate(NewAccount account)
{
// ...
}
// technical validation carried out at the application level
private void Validate(NewAccount account)
{
if (!account.Email.Contains("@"))
throw new ValidationFailure("Not a valid email address");
if (account.Email.Length >= 50)
throw new ValidationFailure("Email address must be less than 50 characters");
if (account.Nickname.Length >= 25)
throw new ValidationFailure("Nickname must be less than 25 characters");
if (String.IsNullOrWhiteSpace(account.Email))
throw new ValidationFailure("You must supply an email");
if (String.IsNullOrWhiteSpace(account.Nickname))
throw new ValidationFailure("You must supply a Nickname");
}
public void RecommendAFriend(int referrerId, NewAccount friendsAccountDetails)
{
Validate(friendsAccountDetails);
// most technologies have similar transaction APIs
using (var transaction = new System.Transactions.TransactionScope())
{
try
{
// customerDirectory is a domain repository
var referrer = customerDirectory.Find(referrerId);
var friend = customerDirectory.Add(friendsAccountDetails);
// referAFriend policy is a domain policy
referAFriendPolicy.Apply(referrer, friend);
transaction.Complete();
// log here to keep to avoid cluttering domain
logger.Debug("Successful friend recommendation");
StatsdClient.Metrics.Counter("friendReferrals");
}
catch (ReferralRejectedDueToLongTermOutstandingBalance ex)
{
logger.Error(ex);
StatsdClient.Metrics.Counter("ReferralRejected");
throw new ApplicationError(
"Sorry, this referral cannot be completed. The referrer " +
"currently has an outstanding balance. Please contact " +
"customer support"
);
// transaction will roll back if Complete() not called
}
}
}