Trigger to prevent deletion of account which has atleast one contact linked to it not working

Question

I am trying to create a Trigger which will prevent deletion of Account which has atleast one contact linked to it. But its not working. Here is my code

trigger AccountDeleteonPrevention on Account (before delete) {
    if(Trigger.isBefore && Trigger.isDelete){
        for(Account acc: Trigger.old){
            if(acc.Contacts.size() > 0){
                acc.addError('You cannot delete this account');
            }
        }
    }
}

When I'm deleting Accounts which have contacts in my org they are getting deleted. Also I see that in debugging the value of account.Contacts.size() comes to be 0 which is strange. That's the reason my if block is not getting evaluated. I am unable to understand my mistake here. Please help

Answer 1

If you want to add an error when you are trying to delete account than you need to

1. Retrieve all related contacts

2. Loop through each contact and add AccountId to Set

3. Loop through accounts and add an error if account contains any contact

   trigger Account on Account (before delete) {
   
      if (Trigger.isBefore && Trigger.isDelete) {
         List<Contact> relatedContacts = [SELECT AccountId FROM Contact WHERE AccountId IN : Trigger.oldMap.keySet()];
   
         Set<Id> accIds = new Set<Id>();
         for (Contact contact : relatedContacts) {
             accIds.add(contact.accountId);
         }
   
         for (Account account : trigger.old) {
            if (accIds.contains(account.Id)) {
                account.addError('You cannot delete this account');
            }
         }    
      }
   }
   

Answer 2

How are you getting the Contacts??

Basically, your code is getting nothing when you say acc.Contacts.

Try debugging it in the System debug and check what is the value in your acc.Contacts.

trigger AccountDeleteonPrevention on Account (before delete) {
    
    if(Trigger.isBefore && Trigger.isDelete){
           for(Account acc: Trigger.old){
             System.debug('## Account>Contacts --> '+  acc.Contacts); // According to me This is not list of contacts and that's the issue here.
             if(acc.Contacts.size()>0){
                   acc.addError('You cannot delete this account');
                   
               }          
       
    }
        
    }
   
}

Solution: I think you should create a field to maintain the Contact record count on the Account and then add that field to your condition.

Answer 3

trigger preventAccountDeletion on Account (before delete) {
    // Check if the trigger is before delete
    if (Trigger.isBefore && Trigger.isDelete) {
        // Query for account IDs that have related contacts
        List<AggregateResult> accountWithContact = [
            SELECT AccountId
            FROM Contact
            WHERE AccountId IN :Trigger.oldMap.keySet()
            GROUP BY AccountId
            HAVING COUNT(Id) > 0
        ];

        // Throw an error if there are accounts with related contacts
        if (accountWithContact.size() > 0) {
            Trigger.old[0].addError(accountWithContact.size() + ' Accounts cannot be deleted because they have related contacts.');
        }
    }
}

Answer 4

Maybe u can try this as well

trigger demoAcct on Account (before delete) {
    for(Account ac:trigger.old){
        List<Contact> relatedConList = [Select AccountId from Contact Where AccountId=: ac.Id];
        if(relatedConList.size()>0){
            ac.addError('You cannot delete this account');
        }
    }
}