Trigger On Attachment Object Salesforce!!

Hi Guys!!

Hope you doing well.

One of my blog reader asked me to share code of trigger on Attachment object . Although , I have already written a trigger on attachment object. For the same click here. but this time I have got a different scenario.

Caution Notice :P :- This blog is meant for beginners like me, who are still learning  salesforce or must say it is for those who are loving salesforce.

Scenario:-  When an attachment is inserted under an account or a contact or Lead  etc.Now, on the basis of a custom field on parent of attachment object, it should check whether any other record exist with same value of field . If there exist some record then this lead should get deleted and and the attachment should be attached to older one. 

So , lets begin with it . Lets Say , I have acustom field on Lead object name as My_name__c on lead objec. On the basis of this field I ll check whether there exist some records or not. so lets Jump to code .

trigger DeleteLeadIFNewMatchesOld on Attachment (Before insert) {
    Set<Id> setOfNewLead = new Set<Id>();
    Set<String> setOfMyname = new Set<String>();
    Set<Id> setOfDeleteLeads = new Set<Id>();
    for(attachment a : trigger.new ){
        setOfNewLead.add(a.ParentId);
    }
    Map<Id,lead> mapOfNewLead = new Map<Id,Lead>([Select id , My_name__c from Lead where id in :  setOfNewLead]);
    Map<Id,Lead> mapOfOldLead = new Map<Id,Lead>([Select id , My_name__c from Lead where  id not in :  setOfNewLead]); 
//    Map<Id,String> = new Map<Id,String>();
    System.debug(mapOfOldLead);
     //if(mapOfNewLead.get(a.ParentId).My_name__c == mapOfOldLead.get())
        for(Lead ld : mapOfNewLead.values()){
           //System.debug('myname'+myname);
            System.debug('mapOfNewLead.values()'+mapOfNewLead.get(ld.Id).My_name__c);
            String myname = mapOfNewLead.get(ld.Id).My_name__c;
            setOfMyname.add(myname);
        }
        for(attachment a : trigger.new ){
            System.debug(setOfMyname);
            System.debug('==19'+mapOfNewLead.get(a.ParentId).My_name__c);
                System.debug('===');
                //Id testId = [Select Id from Lead where My_name__c in]
                for(Id getIdMap : mapOfOldLead.keySet()){
                    if(setOfMyname.contains(mapOfOldLead.get(getIdMap).My_name__c)){
                        setOfDeleteLeads.add(a.ParentId);
                        a.ParentId = getIdMap;
                }

            }
        }
        List<Lead> deleteList = [Select id from Lead where Id in : setOfDeleteLeads];
        delete deleteList;
}

try this Code and then let me know how can I improve this code . I have made it quite complex. 
ThanksAnkush 

Cheers
ankushsalesforce@gmail.com

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