Apex trigger to update checkbox in related field

Question

new at Apex having an issue with creating a trigger. I'm trying to update the value of a picklist depending on if a checkbox is checked in Carrier_Product__c. I know you cannot do this method, and it relies on another lookup where it won't return null. Here's what I have, thank you.

trigger ShellPolicyRebalance on Quote_Policy__c(before insert) {
  for (Quote_Policy__c p: Trigger.new) {
    if (p.RecordTypeId == Schema.SObjectType.Quote_Policy__c.getRecordTypeInfosByName().get('Shell Policy').getRecordTypeId()) {
      if (p.Carrier_Product__r.Rebalance__c) {
        p.Renewal_Flow__c = 'Rebalance';
      }
    }
  }
}

Answer 1

This is probably doable in a flow... but to do this in a trigger, there are some generic steps that you can follow.

1. Get get all the carrier product ids. Put them in a list or a set by looping Trigger.new

2. Query the Carrier_Product__c object to get the checkbox field that you want. eg [SELECT Id, Rebalance__c FROM Carrier_Product__c WHERE Id IN :carrierProductIdList ];

3. Put the results of this query into a Map<Id,Carrier_Product__c>

4. Loop Trigger.new and use the product id to get the correct carrier product out of the map.

5. Examine the value and set/unset the checkbox.

6. This should be a before trigger, so you don't need to update.

Answer 2

you cannot get relationships value in trigger.new . p.Carrier_Product__r.Rebalance__c will not return correct value.

use after insert instead of before insert and iterate over records using soql. finally update records using dml.

something like that (just a sample code. did not tested it. you might also want to include recursive check.)

trigger ShellPolicyRebalance on Quote_Policy__c(after insert) {
  List<Quote_Policy__c> recordsToUpdate = new List<Quote_Policy__c>();
  for (Quote_Policy__c p: [select id,recordtypeid,Carrier_Product__r.Rebalance__c,Renewal_Flow__c  from Quote_Policy__c   where id in :Trigger.new) {
    if (p.RecordTypeId == Schema.SObjectType.Quote_Policy__c.getRecordTypeInfosByName().get('Shell Policy').getRecordTypeId()) {
      if (p.Carrier_Product__r.Rebalance__c) {
        p.Renewal_Flow__c = 'Rebalance';
        recordsToUpdate.add(p);
      }
    }
  }

if(recordsToUpdate.size()>0)
  update recordsToUpdate ;
}

on a side note, your problem statement is more suited for flow. flow will be a better option than trigger.