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Salesforce developer interview questions and answers || 2022 || Part 2 || APEX (Continued)

Salesforce developer interview questions and answers || 2022 || Part 2 || APEX (Continued)

Ashfaq Mohammed

25:35

Overview

This video continues a series on Salesforce developer interview questions, focusing on Apex. It covers transactional control statements, explaining their use in managing multiple DML operations and ensuring data integrity. The discussion delves into mixed DML operations errors, differentiating between setup and non-setup objects, and lists objects that do not support DML. Record locking using 'for update' is explained, along with its benefits and the concept of deadlocks and how to avoid them. Dynamic Apex and dynamic SOQL/SOSL are presented as tools for creating flexible, reusable code. Finally, the video clarifies the 'with sharing' and 'without sharing' keywords, their impact on Apex execution context, and introduces Apex sharing as a programmatic way to manage record access when standard configurations are insufficient.

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  • •Used when multiple DML statements need to be executed together.
  • •Allows rollback of all DML operations if any single operation fails.
  • •Example: Inserting an account and its related contacts; if contact insertion fails, the account insertion should also be rolled back.
  • •Key statements: `database.savepoint` and `database.rollback`.
  • •Occurs when DML operations on setup and non-setup objects are performed in the same transaction.
  • •Setup objects include: User, UserRole.
  • •Non-setup objects include: Account, Lead, Opportunity.
  • •Example: Inserting an Account (non-setup) and a User (setup) in the same transaction.
  • •Some standard objects, known as system objects, do not support DML operations.
  • •Examples: Task, Event, BusinessProcess, CategoryNode, CurrencyType, Profile, RecordType, StaticResource.
  • •These objects are typically managed by Salesforce internally or have specific access methods.
  • •The `for update` clause in SOQL locks records during updates to prevent race conditions.
  • •A locked record cannot be modified by other users or code until the transaction completes.
  • •Deadlocks occur when two or more transactions are waiting for each other to release locks.
  • •To avoid deadlocks, Apex locks parent records before child records and locks records in order of their IDs.
  • •Dynamic Apex allows for more flexible applications using describe information.
  • •Enables writing generic code that can be reused across multiple sObjects without hardcoding object or field names.
  • •Dynamic SOQL/SOSL involves constructing SOQL or SOSL query strings at runtime.
  • •Used with `database.query` method to handle conditional queries or queries with dynamic fields.
  • •Keywords `with sharing` and `without sharing` control enforcement of user permissions and field-level security.
  • •`with sharing` enforces the running user's permissions.
  • •`without sharing` (or no keyword specified) runs in a system context, ignoring user permissions (default behavior).
  • •The context of the calling class determines the sharing context if not explicitly defined in the called class.
  • •Apex Sharing is the programmatic way to share records when standard configurations (ownership, hierarchy, sharing rules) are insufficient.
  • •Utilizes associated 'Share' objects (e.g., AccountShare, LeadShare) for each sObject.
  • •Allows granular control over record access based on complex, dynamic conditions.
  • •Data is stored in the respective `ObjectName__Share` objects.

Key Takeaways

  1. 1Transactional control statements (`savepoint`, `rollback`) are crucial for maintaining data integrity across multiple DML operations.
  2. 2Be aware of mixed DML operations errors and the distinction between setup and non-setup objects.
  3. 3Understand record locking (`for update`) and deadlock scenarios to ensure robust data manipulation.
  4. 4Dynamic Apex, SOQL, and SOSL enhance code flexibility and reusability by allowing runtime construction of queries and object interactions.
  5. 5The `with sharing` keyword is essential for enforcing user permissions and security in Apex code.
  6. 6Apex Sharing provides a programmatic solution for complex record sharing requirements beyond standard configurations.
  7. 7Always refer to official Salesforce documentation (Help & Trailhead) for the most up-to-date information.
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