Example: How to write a deduping trigger for leads and contacts

Hey David,

While the code works for single lead creation, this will be a problem for bulk Lead inserts (SOQL more than 100). I was playing around for bulk check and this works!

Trigger Code:
trigger LeadTrigger on Lead (before insert, before update) {

LeadHandler handler = new LeadHandler();
if (Trigger.isBefore) {
if (Trigger.isInsert) {
handler.onBeforeInsert(Trigger.new);
}
if (Trigger.IsUpdate) {
// handler.onBeforeUpdate(Trigger.new, Trigger.Old);
}
// More event checks if needed
}
}

Handler code:
public class LeadHandler {
Public void onBeforeInsert(List newLeadList) {
Map emailLeadMap = new Map();
for (Lead leadVar : newLeadList) {
emailLeadMap.put(leadVar, leadVar.email);
}
checkDupes(emailLeadMap);
}

private void checkDupes(Map emailLeadMap) {
Map emailContactMap = new Map();
// Get all contacts with matching emails
for (Contact contactVar : [SELECT Email FROM Contact WHERE Email IN :emailLeadMap.values()]) {
// This map can be replaced by Set of emails as well :)
emailContactMap.put(contactVar.email, contactVar);
}
// For every incoming Lead, check if contacts with matching emails were found
for (Lead leadVar : emailLeadMap.keyset()) {
if (emailContactMap.containskey(leadVar.email)) {
leadVar.addError(‘ContactAlreadyExist’);
}
}
}
}

Tested it with Data Import Wizard for about 200 test leads and it allows partial inserts. Pardon my missing comments :)

Many Thanks David. Created first trigger. Simply thanks Man.
I am a novice to coding and you have inspired me.

Thanks
Charu

David,
It should be Dupe_Contact__c instead of Contact_Dupe__c in the line just below your code snippet:

“Note that users will receive an error message via a validation rule anytime the Contact_Dupe__c field is populated. Apex is often mixed with point-and-click functionality!”

Hello David,

Thank you for putting the sfdc99 resource together for guys(/and girls) like me. I am new to coding, thanks to your site (and constant google searches) I feel like I am starting to understand what is apex coding. (Cant say yet that I understand how to code apex, but man it is night and day from before I found this site)

I am currently an Admin and have been trying to find a way to prevent duplicate records with in our salesforce contacts object. I thought I would take a stab at writing code for this and modeled it upon your example found in your beginner lessons.

Here is my logic.

1. Contact record is created or updated
2. Contact record has a Name and Birthdate (and are not empty fields)
3. Try to find a matching Contact based upon Name and Birthdate Fields
4. If a match is found, give the user an error message
5. If a match is not found, do nothing

This is my code:

trigger FindDupes on Contact (before insert, before update) {
for (Contact myContact : Trigger.new) {
if (myContact.Name != null) {
if (myContact.Birthdate != null) {

List dupes = [SELECT Id FROM Contact
WHERE Name = :myContact.Name
AND Birthdate = :myContact.Birthdate];
if (dupes.size() > 0) {
String errorMessage = ‘Duplicate contact found! ‘;
errorMessage += ‘Record ID is ‘ + dupes[0].Id;
myContact.addError(errorMessage);
}
}
}
}
}

I have created a sandbox and added this trigger to the Contacts trigger section. Salesforce accepted the trigger with no error message (it took me many multiple attempts to get no errors), however, when I go to test this code and create several duplicate records – I don’t see an error message when I should, under instances that i create a duplicate contact (name and Birthdate) or anytime I update a record (that is a duplicate record).

Am I missing something or just completely off base? (idk anymore I’ve been staring at my computer screen for hours all weekend trying to figure it out). Any help is greatly appreciated.

Thanks in Advance

-Nate

Hi David,

I wrote this code to update a Email Field Called Data partner Contacts email poc, based on the lookup field MCA data partner poc (look up to a custom object MCA data partner contacts, which has name and email). I want the email address on the child object. the code I wrote is not working, and I am unable to figure out why, can you please help? really appreciate it

trigger UpdateDataPartnerContactEmails on MCA_Campaign__c (After Insert, After update) {

//String x = MCA_Campaign__c.MCA_Data_Partner_Contact__r.Contact_Email__c;
for (MCA_Campaign__c Mca : Trigger.new) {
if (Mca.MCA_Data_Partner_Contact__c != null) {

List Partners = [SELECT Id, Contact_Email__c FROM MCA_Data_Partner_Contacts__c WHERE Name = :Mca.MCA_Data_Partner_Contact__c];

if (Partners.size() > 0){
Mca.Data_Partner_PoC_1_email__c = Partners[0].Contact_Email__c;
update Mca;
}
}
}

}

Hi David,

I have usecase, wherein in an opportunity I should be able to add only one product. Could be please tell me how to go about it
Thanks

Hi David
I have a strange issue here . I have written the below deduping trigger based on your webinar. I have defined the Dupe contact fields as a text field and have a validation rule on it. I am getting the error while insert/update with a duplicate email id, but the value of the Id field is not getting populated in the Dupe Contact field. What am I missing here ? (So, I am getting a validation error on the Dupe Contact field but the field itself is blank)

trigger DetectDupes on Contact (before update, before insert) {
for (Contact l : Trigger.new) {
if (l.Email != null) {
String contactEmail = l.Email;
list dupeContacts = [Select Email from Contact
where Email = :contactEmail];
if (dupeContacts.size() > 0) {
l.Dupe_contact__c = dupeContacts[0].Id;
} else {
l.Dupe_contact__c = null;
}
} else {
l.Dupe_contact__c = null;
}
}
}

Hi David, this is in continuation to my previous reply.

I modified the code with the following to check only when the lead status is not ‘
closed converted’ as this is the status that every lead gets on conversion.

This has fixed the problem for now.

if(leadforDupe.Email != null && leadforDupe.Status ‘Closed – converted’ )

Hi David,

Thank you for your tutorials. I know nothing about coding, so your tutorials are easy to follow. I want to create a trigger that calculates the # of activity per opportunity. The roll-up summary is very limited in Salesforce and I think a trigger would give me the activity count. Please advise. Thanks in advance for your help.

Just to improve upon the great work, you can also use getLevenshteinDistance method to find similar emails too, so for example you can take the string, strip out the domain(to reduce the Levenshtein’s Distance) and see how many similar records are there with a Distance of 2-5 so you can calculate it for user typo’s or different spelling combinations.

Hi David,
Once again — great site — I am really enjoying your work; not just the lessons but the entire site structure and how you have it tied in with WordPress – slick stuff. I am impressed with your energy level! Keep it going! :)

In regard to the code example above and to make sure that I am not misunderstanding things that I thought I knew and continue to learn — would you say that the SELECT query on the contacts should not be inside the trigger.new loop? Would it be best to some how get a map of the contacts prior to the trigger loop? Am I wrong or are you building us up to that and want to keep the lessons learned as basic as possible?

I just want to make sure I am staying on the right track so I appreciate your feedback.

Tom B.

Hi David,

Not sure if you received my last comment as it does not appear to have posted. I wanted to thank you for providing the most easy to understand tutorials for beginners trying to learn apex. Please keep on posting. Also, could you possibly send me some intermediate sample trigger exercises (like the deduping one) so that I can try to create them? I would really appreciate it. I am getting to grips with Apex at a phenomenal rate thanks to this site.

Thank you
Graham