Trigger For Restrict Same Contact On Bulk Insert

Question

My requirement is to perform the bulk insert(50 or 60 records), and restrict duplicate contacts. My trigger is working for 1 record, but not for many at the same time.

Here is my trigger:

Trigger duplicatecOn on Contact (before insert) 
{
    List<Account> accList = new List<Account>();
    Set<Id> accIdSet = new Set<Id>();
    for(contact con : trigger.new)
    {
        accIdSet.add(con.accountId);
    }

    Map<Id, Account> accountsMap = new Map<Id, Account>([Select id, name, (Select id, lastname From Contacts) From Account
                                                            Where Id IN : accIdSet]);
    for(contact con : trigger.new)
    {
        Account acc = accountsMap.get(con.accountId);
        for(Contact cont : acc.contacts)
        {
            if(con.lastname == cont.lastname)
            con.addError('Contact with same name already exists');
        }
    } 
}

Answer 1

The problem here is that you are only ever checking your new records against existing records - and never updating the existing records with new records. So if you have an Account with 1 contact (Smith) and you are loading in 3 Contacts (Smith, White, White) - given this code Smith would fail but both Whites would be inserted, that is because once you process the first White you need to add it to the accountsMap so the second White will detect it.

for(contact con : trigger.new)
{
    boolean errored = false;
    Account acc = accountsMap.get(con.accountId);
    for(Contact cont : acc.contacts)
    {
        if(con.lastname == cont.lastname){
        con.addError('Contact with same name already exists');
        errored = true;
        } 
    }
    if(!errored){
        //Add con to accountMap
    }
}