Exam & Interview Guide

How to Pass Technical Screening Interviews for Salesforce Platform Developer I

A complete step-by-step masterclass on passing Salesforce Platform Developer I technical screening interviews, Apex programming, SOQL/SOSL query optimization, Triggers bulkification, and Lightning Web Components (LWC).

By Careers.codes Salesforce Engineering Team | 5 min read

Summary: Master Salesforce Governor Limits, Apex Trigger bulkification, SOQL vs SOSL queries, asynchronous Apex (Queueable, Batch), and Lightning Web Components (LWC) for Platform Developer I interviews.

1. Platform Developer I Exam & Salesforce Screening Scope

The Salesforce Certified Platform Developer I certification evaluates technical competence in building custom business logic and user interfaces on the Lightning Platform using Apex and SOQL. 1. **Developer Fundamentals (27% Weighting):** Salesforce architecture, Multi-tenant environment, Object relationships (Master-Detail vs Lookup), Formula fields, Roll-up Summary fields. 2. **Process Automation & Logic (28% Weighting):** Apex classes, Triggers, Governor Limits, SOQL/SOSL queries, Asynchronous Apex, Exception handling. 3. **User Interface (25% Weighting):** Lightning Web Components (LWC), Aura Components, Visualforce pages, Controller extensions, LDS (Lightning Data Service). 4. **Testing & Deployment (20% Weighting):** Apex test classes (75% code coverage requirement), Test data factory pattern, Change Sets, Salesforce CLI (sf / sfdx), Sandboxes.

2. Salesforce Governor Limits & Apex Bulkification

**Interview Scenario:** *"Why do Salesforce Governor Limits exist, and how do you write bulkified Apex Triggers that handle 200 records in a single transaction?"* * **Multi-Tenant Architecture:** Salesforce executes code in a shared multi-tenant environment. Governor Limits enforce hard thresholds (e.g. 100 SOQL queries per transaction, 150 DML statements) to prevent a single tenant from hogging server resources. * **Bulkification Rule #1: Never Put SOQL Queries or DML Inside Loops!** - **Wrong (Hits limit at 101 records):** `for(Account acc : Trigger.new) { List cons = [SELECT Id FROM Contact WHERE AccountId = :acc.Id]; }` - **Correct (1 SOQL query for all records):** `Set accIds = Trigger.newMap.keySet(); List cons = [SELECT Id, AccountId FROM Contact WHERE AccountId IN :accIds];`

3. SOQL vs SOSL Queries & Relationship Traversal

**Interview Scenario:** *"When should you use SOQL vs SOSL in Salesforce, and how do child-to-parent vs parent-to-child queries differ?"* * **SOQL (Salesforce Object Query Language):** Evaluates a **single sObject** type (or related sObjects). Returns a `List`. Equivalent to SQL `SELECT`. * **SOSL (Salesforce Object Search Language):** Text search engine searching keywords across **multiple sObject types** simultaneously (e.g. `FIND {Acme} IN ALL FIELDS RETURNING Account, Contact, Lead`). Returns `List>`. * **Relationship Traversal:** - **Child-to-Parent (Upwards - Dot Notation):** `SELECT Id, Name, Account.Name, Account.Owner.Email FROM Contact` - **Parent-to-Child (Downwards - Subquery):** `SELECT Id, Name, (SELECT Id, LastName FROM Contacts) FROM Account`

4. Asynchronous Apex: Queueable vs Batch vs Future Methods

**Interview Scenario:** *"Compare `@future` methods, `Queueable` Apex, and `Batch Apex` for long-running backend processing."* * **`@future` Methods:** Simple async execution for web service callouts or bypassing MIXED_DML errors. Cannot return job IDs or accept complex object parameters. * **`Queueable` Apex:** Modern replacement for `@future`. Accepts complex object parameters, returns AsyncApexJob IDs, and supports job chaining (`System.enqueueJob()`). * **`Batch Apex`:** Designed for processing millions of records. Implements `Database.Batchable`, breaking large record sets into small transactions (default 200 records per execution batch).

5. Lightning Web Components (LWC) & Event Propagation

**Interview Scenario:** *"How do parent and child components communicate in Lightning Web Components (LWC)?"* * **Parent to Child Communication:** Parent passes data to child using public reactive properties annotated with `@api` in the child component (`@api recordId;`). * **Child to Parent Communication:** Child dispatches custom DOM events: `this.dispatchEvent(new CustomEvent('select', { detail: { id: this.contactId } }));` Parent handles the event in template: ``. * **Wire Service (`@wire`):** Reactively reads Salesforce data directly from Lightning Data Service cache without writing manual Apex controllers.