EPAM Salesforce developer interview questions

Quick answers to key questions

Short answers to the main questions from this EPAM interview.

• Convert a 15 digit Id to 18 digit in a formula. Use the CASESAFEID() function. In Apex, assigning a 15 digit Id to an Id variable gives the 18 digit version.
• Validation rule or trigger first? Before triggers run first, then system validation and custom validation rules run. So if a before trigger sets the field, the validation rule sees that value.
• Use of AuraEnabled. It exposes an Apex method to LWC and Aura components. Add cacheable=true when the method only reads data and is used with @wire.
• Master-detail relationship. The detail record cannot exist without the master, inherits its sharing and owner, is deleted together with the master, and supports roll-up summary fields. Use it when the child is tightly part of the parent.
• DML in before triggers. You do not need DML to save changes to the records in Trigger.new, because Salesforce saves them for you. Running DML on the same record would cause errors or recursion. In a before insert trigger the record Id does not exist yet.
• Enforce field-level security in Apex. Use WITH USER_MODE or WITH SECURITY_ENFORCED in SOQL, Security.stripInaccessible() to remove fields the user cannot access, or schema describe methods such as isAccessible().
• Can we pass a list to a future method? Only a list of primitive values, such as List<Id>. Future methods cannot take sObjects or other objects as parameters.
• Managed and unmanaged packages. Managed packages are meant for distribution, have a namespace, hide their code, have versions and can be upgraded. Unmanaged packages are a one-time copy of the components, the code can be edited, and there are no upgrades.
• System context and user context. Apex normally runs in system context, so it ignores the user object and field permissions. Sharing is enforced only if the class uses with sharing. User mode (for example WITH USER_MODE) applies the running user permissions.
• Formula in a roll-up summary. A roll-up summary cannot use a formula field that references another object, so such a calculation needs a trigger or a flow instead.
• Manual sharing when ownership changes. Manual sharing records are removed when the record owner changes, so access must be shared again if it is still needed.
• Prevent more than one primary contact. Use a before insert and before update trigger (or a record-triggered flow) that checks whether another Contact on the same Account is already marked as primary, and call addError() if it is.
• What is LDS? Lightning Data Service lets components read and save a single record without Apex. It respects sharing and field-level security, caches the data and shares it between components. The limits: it handles single records, it cannot run complex queries, and it does not fit bulk operations.
• Cross-object formula field. A formula field that shows a value from a related parent record, for example the Account Industry on a Contact.