Create a Trigger to merge Leads if the Email already exists on a Lead

Question

I have multiple Web-to-Lead forms that gather information for different fields. I want to store all the info under one lead, with the email address being the key. I want to create a trigger to query Leads to see if the email exists. If it does, I want to add this information on to the existing Lead. I am able to find if there is a duplicate email address, but I don't know how to merge the two together.

trigger leadDupeMerge on Lead (before insert) {
Set<String> emails = new Set<String>();
for(Lead ld : trigger.new){
    emails.add(ld.Email);
}
emails.remove(null);
for(Lead ld: [SELECT Email FROM Lead WHERE Email = :emails]){
    emails.remove(ld.Email);
}
for(Lead ld : Trigger.new){
    if(ld.Email != null && emails.contains(ld.Email)){
        ld.Email.addError('This lead matches an existing email.');
    }
}

}

Answer 1

You'll need to use after insert instead if you want to perform an actual merge operation. That logic would look like:

trigger leadDupeMerge on Lead (after insert) {
    Set<String> emails = new Set<String>();
    Map<String, Lead> masters = new Map<String, Lead>();
    for(Lead ld : trigger.new){
        emails.add(ld.Email);
    }
    emails.remove(null);
    for(Lead ld: [SELECT Email FROM Lead WHERE Email = :emails AND Id NOT IN :Trigger.new AND IsConverted = false]){
        masters.put(ld.Email, ld);
    }
    for(Lead ld : Trigger.new){
        Lead master = masters.get(ld.Email);
        if(master != null) {
            merge master ld;
        }
    }
}

Notes:

• No error handling is provided here. If you run into errors, you'll need to handle those.
• If a user performs a create through the UI and it is a duplicate, they'll see a "record deleted" page instead of the lead they just created.
• Merges can't be bulkified, so you may want to return early if the list size is greater than 1 (web-to-lead and the like usually insert one record at a time).