How get Lead Id in apex trigger

Question

When sending an email from the lead screen. Is it possible to get the lead id in the before of the EmailMessage trigger?

Answer 1

For objects other than Lead and Contact

The before trigger on EmailMessage should include a value for RelatedToId which is the parent of the email message (e.g., the Opportunity.Id). Your trigger will need to requery to get values from the Opportunity and do so in a bulkified manner.

Note that EmailMessage.RelatedToId is polymorphic and not every EmailMessage will have an Opportunity as parent. Thus, you'll want code something like

for (EmailMessage em: Trigger.new) {
  if (em.RelatedToId.getSobjectType() == Opportunity.SObjectType) {
      // collect the RelatedToIds in a set to query for Opportunities
  }
}

// bulkified query for Leads and put in map<ID,Opportunity>

// second pass through Trigger.new to deal with EmailMessage for Opportunity

For emails sent from Lead or Contact

• the beforeInsert trigger has no value for RelatedToId
• the afterInsert trigger has no value for RelatedToId
• the afterInsert trigger does have a value for ActivityId that points at a Task and the Task.WhoId points at the Lead (or Contact).

So, you'll need to use an afterInsert trigger, query (bulkified) all parent Task including their WhoId field

Set<Id> taskIds = new Set<Id>();
for (EmailMessage em: Trigger.new) {
  taskIds.add(em.ActivityId);
}

Task[] tasks = SELECT 
    TYPEOF Who
       WHEN Contact THEN Id, Email, FirstName, LastName, Account.Name
       WHEN Lead THEN Id, Company, Email
       ELSE Name
    END
    FROM Task WHERE Id IN: taskIds;

 // do something with the Tasks that reference Leads