One of the custom objects I have is rendered as a Related List of Opportunity. This custom object also has a custom field of Opportunity lookup type. To create a record of this type I go to
Opportunity -> Related List and click on
What I want is : At the time of record creation I want to assign default values to certain fields. The way it should work is
Mailing Address field should get its value from related Opportunity's primary Contact. I can achieve this in a trigger by executing a query like
SELECT MailingAddress from CONTACT WHERE id IN (SELECT contactID FROM OpportunityContactRole WHERE opportunityID = <variable> and isPrimary = true)
However, I want to do it by assigning a formula to the default value to Mailing Address filed directly. Is it possible?
Second part of this question is... While trying to set the default value for this custom field I tried something like
Opportunity__c.Mailing_Address__c (This is a custom field on Opportunity), however the formula validation error I got was
Error: Field Opportunity__c does not exist. Check Spelling.
Opportunity__c in fact exists as a lookup Opportunity Field in my custom object.
Any pointers are greatly appreciated.