How can I prevent an outcome from being registered multiple times?

Question

What is the accepted method of preventing a contact from registering an outcome multiple times? For example, if they become a "Marketing Lead", how do I prevent that Outcome from firing again for that contact?

Do you need to programmatically check to see if the outcome has already been registered for the contact? Or is there a configuration setting for this?

I see the "Ignore Additional Registrations" checkbox, but I am not sure what it does.

I am using Sitecore 8.1 Update 2 with xDB Cloud.

Answer 1

You are correct—the "Ignore Additional Registrations" checkbox will make sure that nothing happens in case an existing outcome is attempted to be registered again.

Here's an excerpt from the decompiled class Sitecore.Analytics.Outcome.OutcomeManager:

public virtual void Save(IOutcome outcome)
{
  if (!this.CanSaveOutcome(outcome))
  {
    return;
  }

  this.repository.Save(outcome);
}

private bool CanSaveOutcome(IOutcome outcome)
{
  IDefinitionManager<IOutcomeDefinition> definitionManager =
    DefinitionManagerFactory.Default.GetDefinitionManager<IOutcomeDefinition>(null);

  IOutcomeDefinition outcomeDefinition =
    definitionManager.Get(outcome.DefinitionId, CultureInfo.InvariantCulture);

  return
    outcomeDefinition == null
    || !outcomeDefinition.AdditionalRegistrationsAreIgnored
    || !this.HasOutcome(outcome.EntityId, outcome.DefinitionId);
}

As you can see, OutcomeManager.Save() will only register the outcome if the checkbox "Ignore Additional Registrations" is unchecked, or if the outcome has not been registered yet.

As a side note, it's quite interesting that the outcome will be saved successfully even if you specify a non-existing outcome definition ID in outcome.DefinitionId.