Wanted to update few fields by trigger from parent object when new child record is created in salesforce

Question

I want to update address from parent object when new child record is created by trigger because any time i can change the child record but by default it should have address from its parent object.

Answer 1

Then create your trigger upon insert only on the child record. Get the parent record id and address via SOQL . Run over the parent & Child records loop. Check if parent id is same in the child records and the update the address of the child record. Keep in mind not to do DML operation inside your FOR loop.

Sample Trigger Code

Trigger ChildUpdate on Childobject__c(Before Insert)
{
    Set<Id> ParentIds = New Set<Id>();

    For(Childobject__c C : Trigger.New)
    {
        ParentIds.Add(C.ParentId__c);
    }

    List<ParentObjectName__c> ParentList = [Select Id,Address__c from ParentObjectName__c where id =: ParentIds];

    For(Childobject__c CO : Trigger.New)
    {    
        For(ParentObjectName__c PA : ParentList)
        {
            IF(CO.ParentId__c == PA.ID)
            {
                IF(PA.Address__c != NULL)
                {
                    C.ChildAddressField__c = PA.Address__c ;
                }
            }
        }
    }    
}

Answer 2

Instead of a trigger, this can be achieved by using a workflow rule and a field update action.

(Assuming Parent: Account & Child: Contact)

Steps to follow:

1. Create a workflow rule on Contact having criteria "AccountId" (lookup to account) not equal to null.
2. Once created, create field update action (Under Workflow Actions) for updating MailingCity field.
3. In the field update action, under Specify New Field Value, click on formula editor and insert field "Account.BillingCity".
4. Repeat step 3 for rest of the address fields.

Hope this helps.

Best Regards!

Answer 3

Yet another way to achieve this is using trigger. A before insert trigger will be fired which will perform the following operations:

1. Fetch parent record ids from Lookup_To_Parent__c field in trigger.new records and put them in a set<id>.
2. Fetch the address information from related parent records and put them in a map<Id, Parent_Object__c>.
3. Iterate over trigger.new again and populate address fields from related parent by accessing the parent record using get(anyKey); method of map class.

Voila! The address fields are populated now.

Hope this helps.

Best Regards!