How to edit Parent Record from Related Record

Question

Objects : Lead(Parent record),LeadClientInsurance__c (Related records) if I change the First_Name__c in LeadClientInsurance__c object I need to change FirstName in Lead Record.

Theoretically, LeadClientInsurance__c.First_Name__c == Lead.FirstName

If I change LeadClientInsurance__c's First_Name__c, the Lead's FirstName needs to be changed. I need an Apex trigger to work in both ways – if the Lead's FirstName is changed, LeadClientInsurance__c's First_Name__c needs to be changed

Answer 1

You'll want to write two triggers, one for Lead and LeadClientInsurance__c. Both will look very similar. You can also build this design in a flow, but I'm not going to build all that for this question. Just know that it involves the exact same steps: get the related record, check if the values don't match, and if not, then perform an update.

What follows are the most simple trigger implementations to help you get started.

Lead Trigger v1

trigger Lead on Lead (after update) {
  // Get child records
  LeadClientInsurance__c[] leadClientInsurances = [
    SELECT Lead__c, First_Name__c
    FROM LeadClientInsurance__c
    WHERE Lead__c = :Trigger.new
  ];
  LeadClientInsurance__c[] updates = new LeaderClientInsurance__c[0];
  // For each child record, if does not match, update.
  for(LeadClientInsurance insuranceRecord: leadClientInsurances) {
    Lead leadRecord = Trigger.newMap.get(insuranceRecord.Lead__c);
    if(insuranceRecord.FirstName != insuranceRecord.First_Name__c) {
      updates.add(new LeaderClientInsurance__c(
        Id=insuranceRecord.Id,
        First_Name__c=leadRecord.FirstName
      ));
    }
  }
  // update lead client insurance records
  update updates;
}

Lead Client Insurance Trigger v1

trigger LeadClientInsurance on LeadClientInsurance__c (after insert, after update) {
  // Get parent records
  Map<Id, Lead__c> leadRecords = new Map<Id, Lead__c>([
    SELECT FirstName
    FROM Lead
    WHERE Id IN (SELECT Lead__c FROM LeadClientInsurance__c WHERE Id = :Trigger.new)
  ]);
  Map<Id, Lead__c> updates = new Map<Id, Lead__c>();
  // If changed, add to updates map
  for(LeadClientInsurance__c insuranceRecord: Trigger.new) {
    Lead leadRecord = leadRecords.get(insuranceRecord.Lead__c);
    if(leadRecord.FirstName != insuranceRecord.First_Name__c) {
      updates.put(insuranceRecord.Lead__c, new Lead__c(
        Id=insuranceRecord.Lead__c,
        FirstName=insuranceRecord.First_Name__c
      ));
    }
  }
  // update leads
  update updates.values();
}

---

An alternative arrangement checks if the field has changed first, and then makes an update for records that don't have the correct value. This code is slightly better for performance if you know all your data is in sync. Unless you have significant resource usage already, though, I'd probably go with the design above.

Lead Trigger v2

trigger Lead on Lead (after update) {
  Set<Id> leadIds = new Set<Id>();
  for(Integer i = 0; i < Trigger.size(); i++) {
    if(Trigger.old[i].FirstName != Trigger.new[i].FirstName) {
      leadIds.add(Trigger.new[i].Id);
    }
  }
  if(leadIds.isEmpty()) {
    return;
  }
  LeadClientInsurance__c[] updates = new LeaderClientInsurance__c[0];
  for(LeadClientInsurance__c insuranceRecord : [
    SELECT First_Name__c, Lead__c
    FROM LeadClientInsurance__c
    WHERE Lead__c = :leadIds
  ]) {
    Lead leadRecord = Trigger.newMap.get(insuranceRecord.Lead__c);
    if(leadRecord.FirstName != insuranceRecord.First_Name__c) {
      updates.add(
        new LeaderClientInsurance__c(
          Id=insuranceRecord.Id, 
          First_Name__c=leadRecord.FirstName
        )
      );
    }
  }
  update updates;
}

Lead Client Insurance Trigger v2

trigger LeadClientInsurance on LeadClientInsurance__c (after insert, after update) {
  Map<Id, Lead> leadRecords = new Map<Id, Lead>();
  Map<Id, Lead> updates = new Map<Id, Lead>();
  for(Integer i = 0; i < Trigger.size(); i++) {
    if(Trigger.old[i].First_Name__c != Trigger.new[i].First_Name__c) {
      leadRecords.put(Trigger.new[i].Lead__c, null);
    }
  }
  if(leadRecords.isEmpty()) {
    return;
  }
  leadRecords.putAll([SELECT FirstName FROM Lead WHERE Id = :leadRecords.keySet()]);
  for(LeadClientInsurance__c insuranceRecord: Trigger.new) {
    Lead leadRecord = leadRecords.get(insuranceRecord.Lead__c);
    if(leadRecord != null && leadRecord.FirstName != insuranceRecord.First_Name__c) {
      updates.put(new Lead(
        Id=leadRecord.Id,
        FirstName=insuranceRecord.First_Name__c
      ));
    }
  }
}

---

Other arrangements are possible as well. For example, we can make this code more efficient by using a common class to hold data so we don't have to use extra queries, or make it dynamic for which fields we want to map, and so on.

At any rate, this code isn't meant to be production ready. A proper solution should include error handling, support partial success updates, a trigger handler framework for testing and maintenance purposes, and so on. These are minimum implementation solutions designed to show how to deal with bidirectional field updates in Apex code.