Crafting Seamless One-to-One Relationships in Salesforce

Creating a one-to-one relationship between custom objects in Salesforce might seem like a puzzle, especially when Salesforce doesn't offer a direct method.

In this blog, we'll explore user-friendly ways to establish a seamless connection between two objects, say, 'Employee' and 'Aadhar Card.'

Option 1: The Configuration Route

• Lookup Field: Add a lookup field on 'Aadhar Card' linking to 'Employee.'
• Unique ID Field: Create a unique custom field on 'Aadhar Card' to store the associated Employee's ID. Keep this field hidden from page layouts.
• Flow Magic: Set up a Flow on 'Aadhar Card.' Whenever the Employee lookup field changes, update the unique field with the Employee ID. Voila! A one-to-one link is born.

This configuration ensures that trying to add a second Aadhar Card to an Employee triggers an error due to the unique constraint.

Option 2: Master-Detail Mastery

• Master-Detail Relationship: Establish a master-detail link from 'Aadhar Card' to 'Employee.'
• Roll-Up Summary: Create a roll-up summary field on 'Employee' counting Aadhar Cards.
• Validation Rule: Implement a validation rule on 'Employee' to restrict the count to 1. Any attempt to exceed this count results in an error.

This setup ensures a straightforward one-to-one connection; an error will pop up if an Employee attempts to have more than one Aadhar Card.

Option 3: The Mutual Lookup Approach

• Lookup Fields: Introduce lookup fields on both 'Aadhar Card' and 'Employee' linking to each other.
• Trigger Action: Write triggers to manage changes in the lookup fields. Copy IDs when empty or prevent changes when already populated.

This approach maintains a clear one-to-one relationship by managing associations between 'Aadhar Card' and 'Employee.'

Option 4: Trigger Checkup

• Aadhar Card Trigger: Create a trigger on 'Aadhar Card' to verify if a record already exists for an Employee.
• Error Handling: If an Aadhar Card exists, throw an error; if not, allow the creation.

Here's a simplified example showcasing the connection between 'Employee' and 'Aadhar Card' using triggers.

trigger AadharCardValidation on Aadhar_Card__c (before insert) {

    Set<Id> empIdSet = new Set<Id>();
    
    for (Aadhar_Card__c aadhar : Trigger.New) {
        empIdSet.add(aadhar.Employee__c);
    }
    
    for (Employee__c emp : [SELECT Id, (SELECT Id FROM Aadhar_Cards__r) FROM Employee__c WHERE Id IN :empIdSet]) {
        for (Aadhar_Card__c aadhar : Trigger.New) {
            if (emp.Aadhar_Cards__r.size() > 0) {
                aadhar.addError('An Aadhar Card already exists for the Employee: ' + emp.Name);
            }
        }
    }

}        

With these user-friendly options, building one-to-one relationships in Salesforce becomes a breeze. Each approach caters to different needs, providing flexibility and control over your data connections.