Converted Lead - Case created for a Lead, how to link the case to the converted Contact record

Question

I have a use case to link a case records created for a lead record. If lead record gets converted then the related cases should be automatically linked to the converted contact and account record. Please help to check and correct my code below (I am new here, so your help is appreciated.)

public class LeadTriggerHandler {
    public static void updateRelatedContactWithCase(List<Lead> leList, Map<Id, Lead> leOldMap){
        
        List<case> caList = new List<case>();
        Set<Id> leIds = new Set<Id>();
        
        for(Lead le : leList){
            if(le.Status == 'Closed - Converted' && leOldMap.get(le.Id).Status != 'Closed - Converted'){
                if(le.Status == 'Closed - Converted')
                    leIds.add(le.Id);
            }
            System.debug(leIds);
        }
        // To update Lead related Contact to link the case record related to the Lead which was converted.
        if(!leIds.isEmpty()){
            for(Lead le = [SELECT Id, Status,
                           (SELECT Id, Lead__c, AccountId, ContactId FROM Cases__r) FROM Lead WHERE Id IN: leIds]){
                               if(le.cases__r !=null){
                                   for(Cases__r ca : le.Cases__r){
                                       ca.ContactId = le.ConvertedContactId;
                                       caList.add(ca);
                                       
                                   }
                               }
                               if(!caList.isEmpty()){
                                   update caList;
                               }
                               
                           }
        }
        
    }
}

Answer 1

You need to check the isConverted attribute of the lead also to gain more limit on your process i suggest using FUTURE method. Note, The Cases will be visible after some delay not immediately, If you want instant view after conversion do not use FUTURE

public class LeadTriggerHandler {
     public static void updateRelatedContactWithCase(List<Lead> leList, Map<Id, Lead> leOldMap){
        Set<Id> convertedLeadIds = new Set<Id>();
        for(Lead currentLead : leList){
            //conversion is Happening
            if(currentLead.IsConverted){
                convertedLeadIds.add(currentLead.Id)
            }
        }
        if(convertedLeadIds.size() > 0 ){
            //Logic here. 
            //Make a future call to update cases  
            LeadTriggerHandler.processRecords(convertedLeadIds);

        }
     }
    @future
    public static void processRecords(Set<ID> recordIds)
    {   
         // Your logic here 
    }
}