Updating Existing Leads Instead of Creating New Ones

Question

I am new to Apex and trying to solve the following problem using Salesforce Enterprise Edition.

We have a web-to-lead form that collects information about resource downloads. This form captures basic visitor details and includes a custom field to store a description of the downloaded resource. Visitors can download multiple resources, and each download gets logged in a database table. A cron job sends these download details to Salesforce, creating a new lead for each record. However, thinking about updating existing leads instead of creating new ones can be more efficient.

The issue arises when a visitor downloads another resource after their lead has already been created. Instead of updating the existing lead, Salesforce creates a new lead with the new download details. We need to prevent this behavior and instead append the new download details to the existing lead’s description field. To achieve this, I wrote the following trigger:

trigger UpdateLeadDescription on Lead (before insert) {
    // Map to store existing leads by email
    Map<String, Lead> existingLeads = new Map<String, Lead>();

    // Query existing leads by email
    List<Lead> existingLeadList = [SELECT Id, Description FROM Lead WHERE Email IN (SELECT Email FROM :Trigger.new)];
    
    // Populate the map
    for (Lead existingLead : existingLeadList) {
        existingLeads.put(existingLead.Email, existingLead);
    }

    // Iterate through new leads
    for (Lead newLead : Trigger.new) {
        if (existingLeads.containsKey(newLead.Email)) {
            // Lead exists, append description
            Lead existingLead = existingLeads.get(newLead.Email);
            newLead.Description = existingLead.Description + '\n' + newLead.Description;
        }
    }
}

However, the Salesforce Developer Console throws an error at line 6:

List<Lead> existingLeadList = [SELECT Id, Description FROM Lead WHERE Email IN (SELECT Email FROM :Trigger.new)];

The error reads: “Unexpected token ‘<‘.”

Could you help me debug this error and suggest a better approach to solve this issue?

Answer

In Salesforce, the Web-to-Lead feature typically creates a new lead every time a user submits a form. However, there are scenarios where you might want to update an existing lead instead of creating a new one. For example, when a visitor downloads multiple resources, the system should update the existing lead’s details rather than creating a new lead for each download.

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The following trigger demonstrates how to achieve this functionality. It updates the description of an existing lead if a new lead with the same email address is inserted.

trigger UpdateLeadDescription on Lead (before insert) {
    // Set to store emails from Trigger.new
    Set<String> newLeadEmails = new Set<String>();

    // Extract emails from Trigger.new
    for (Lead newLead : Trigger.new) {
        if (newLead.Email != null) {
            newLeadEmails.add(newLead.Email);
        }
    }

    // Query existing leads by email
    Map<String, Lead> existingLeads = new Map<String, Lead>();
    if (!newLeadEmails.isEmpty()) {
        for (Lead existingLead : [SELECT Id, Email, Description FROM Lead WHERE Email IN :newLeadEmails]) {
            existingLeads.put(existingLead.Email, existingLead);
        }
    }

    // Iterate through new leads and update descriptions
    for (Lead newLead : Trigger.new) {
        if (newLead.Email != null && existingLeads.containsKey(newLead.Email)) {
            // Lead exists, append description
            Lead existingLead = existingLeads.get(newLead.Email);
            newLead.Description = (existingLead.Description != null ? existingLead.Description + '\n' : '') + newLead.Description;
        }
    }
}

Explanation:

This code first collects all the email addresses from the incoming leads (Trigger.new). It then queries the existing leads with matching email addresses and stores them in a map. During the before insert phase, it checks if any new lead’s email matches an existing lead’s email. If a match is found, the trigger appends the new lead’s description to the existing lead’s description.

Alternate Approach:

If you want to handle duplicates in a more advanced way, such as deleting the newly created lead after updating the existing one, you can use the following trigger. This version includes a check to delete the new lead if it is redundant.

trigger UpdateLeadDescription on Lead (after insert) {
    // Set to store emails from new leads
    Set<String> setOfNewLeadEmails = new Set<String>();
    
    // Extract emails from Trigger.new
    for (Lead newLead : Trigger.new) {
        setOfNewLeadEmails.add(newLead.Email);
    }
    
    if (!setOfNewLeadEmails.isEmpty()) {
        // Map to store existing leads by email
        Map<String, List<Lead>> mapOfExistingLeads = new Map<String, List<Lead>>();

        // Query existing leads by email
        for (Lead existingLead : [SELECT Id, Email, Description FROM Lead WHERE Email IN :setOfNewLeadEmails AND Id NOT IN :Trigger.new]) {
            if (!mapOfExistingLeads.containsKey(existingLead.Email)) {
                mapOfExistingLeads.put(existingLead.Email, new List<Lead>());
            }
            mapOfExistingLeads.get(existingLead.Email).add(existingLead);
        }

        // List to store leads to update and delete
        List<Lead> listOfLeadsToUpdate = new List<Lead>();
        List<Lead> listOfLeadsToDelete = new List<Lead>();

        // Update and delete logic
        for (Lead newLead : Trigger.new) {            
            if (newLead.Email != null && mapOfExistingLeads.containsKey(newLead.Email)) {
                for (Lead existingLead : mapOfExistingLeads.get(newLead.Email)) {
                    existingLead.Description = (existingLead.Description != null ? existingLead.Description + ' \n ' : '') + newLead.Description;
                    listOfLeadsToUpdate.add(existingLead);
                }   
                listOfLeadsToDelete.add(new Lead(Id = newLead.Id));
            }
        }

        // Perform updates and deletions
        if (!listOfLeadsToUpdate.isEmpty()) {
            update listOfLeadsToUpdate;
        }
        if (!listOfLeadsToDelete.isEmpty()) {
            delete listOfLeadsToDelete;
        }
    }
}

Explanation:
This after insert trigger handles duplicates by updating the description of existing leads and deleting the redundant new leads. It ensures data consistency and prevents unnecessary clutter in the system.

Both approaches can be used depending on your specific requirements. If you’re unsure about the best method for your use case, consider the volume of data, business requirements, and system performance. Let me know if you need further clarification!

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