Scenario:
Objects Involved:
Job__c (Master)
Job_Application__c (Detail)
Contact (Related via Master-Detail relationship on Job_Application__c)
Fields:
Preferred_Locations__c (Multi-select picklist on Job__c)
MailingState (Field on Contact)
Requirement:
On Job_Application__c, display whether the Contact's MailingState matches any value in Preferred_Locations__c on the related Job__c.
Keep this value in sync if changes occur to the Contact's MailingState.
Solution:
Option C: Formula field
Correct Approach.
Create a Formula Field on Job_Application__c that compares the Contact's MailingState with the Job's Preferred_Locations__c.
Since Job_Application__c is a detail of Job__c and has a lookup to Contact, the formula can reference fields from both related objects.
Use the INCLUDES() function to check if the MailingState is among the selected values in Preferred_Locations__c.
Sample Formula:
INCLUDES(Job__r.Preferred_Locations__c, Contact__r.MailingState)
This formula returns a Boolean (TRUE or FALSE) indicating whether there's a match.
Benefits:
Real-Time Calculation: Updates automatically when either field changes.
No Code Required: Declarative solution using formula fields.
Maintenance: Easy to manage and update if needed.
Roll-up Summary Fields are used to perform calculations on detail records and summarize them on the master record.
Cannot be used to compare fields between unrelated objects or for the given comparison.
Option B: Record-triggered flow
Possible but Not Optimal.
A flow could be used to update a field based on changes.
However, it adds complexity and requires maintenance.
Flows consume resources and may have performance considerations.
Option D: Apex trigger
Possible but Overkill.
An Apex trigger can handle the requirement but introduces code maintenance.
Not necessary when a declarative solution exists.
Conclusion:
A Formula Field is the recommended tool to meet the business requirement.
It provides a simple, efficient, and maintainable solution that updates in real-time when data changes.
Reference:
Using Cross-Object Formulas
INCLUDES Function
Why Other Options are Not Suitable:
Option A: Roll-up summary field
Incorrect Use Case.