DEV-450 Sample Questions & Answers

In Salesforce's multi-tenant architecture, all customers (tenants) on a given instance share the same application and hardware resources. To prevent any single tenant from monopolizing these resources and degrading performance for others, Salesforce enforces strict governor limits on code execution (e.g., CPU time, heap size, number of SOQL queries). This forces developers to write efficient, bulkified code.

The standard and most effective pattern to prevent trigger recursion is to use a static boolean variable. Static variables retain their value for the duration of a single transaction. The trigger logic can check the value of this variable; if it's false, the logic executes and sets the variable to true. If the trigger is re-entered within the same transaction, the check will find the variable is true, and the logic will be skipped, thus breaking the recursive loop.

This is true. A single LWC JavaScript file can use ES6 import statements to bring in @AuraEnabled static methods from various Apex classes. Each import statement specifies the method and the class it belongs to, allowing the component to call server-side logic from multiple sources as needed.

To query child records from a parent, a parent-to-child subquery (also known as a left outer join) is used. The syntax involves nesting a SELECT statement for the child objects inside the field list of the parent query. For standard relationships, the plural name of the child object is used (e.g., (SELECT Id, Name FROM Contacts)).

The Apex CPU time limit exceeded error in a batch job typically points to inefficient code within the execute method. Each execution of this method runs in its own transaction with its own set of governor limits. If the logic inside the execute method (e.g., nested for-loops, complex string manipulations, inefficient algorithms) takes too long to run for the given batch of records, it will exceed the CPU time limit (60,000 ms for asynchronous Apex). While a large batch size can contribute, the root cause is usually the code's inefficiency per record.

Lightning Web Components use the Shadow DOM, a web standard, to provide style and DOM encapsulation. This creates a boundary around the component, preventing styles from leaking out and, by default, preventing external styles from leaking in. The component's CSS is scoped to its own shadow tree, ensuring that style rules only apply to the elements within that component.

A Full Sandbox is a copy of your entire production organization, including all data (like records and attachments) and metadata. This makes it the only suitable environment for realistic performance testing, load testing, and staging, as it mirrors the production environment's scale and complexity.

A Validation Rule is the ideal tool for this scenario. It is a declarative feature designed specifically to prevent records from being saved if they do not meet defined criteria. The formula can easily check the field values and the current user's profile. The formula would look something like: AND(NOT(ISBLANK(Email)), NOT(ISBLANK(EmailBouncedDate)), $Profile.Name = 'Sales User'). This is far more efficient and maintainable than writing an Apex trigger for simple validation logic.

The 'Model' in MVC represents the data and business logic. In Salesforce, this is perfectly represented by sObjects (Standard and Custom Objects), which define the data structure, fields, relationships, and validation rules.

The 'Controller' processes user input and interacts with the model. In Salesforce, Apex classes, such as custom Visualforce controllers, controller extensions, and Apex methods called from Lightning components, fulfill this role by executing business logic and performing data operations.

The lightningStylesheets="true" attribute on the tag automatically incorporates the Salesforce Lightning Design System (SLDS) stylesheets into the Visualforce page. This makes the page adopt the look and feel of Lightning Experience without requiring manual inclusion of the SLDS library.