Magento 2 Certification Preparation
What is Dependency Injection (DI) in Magento 2?
Dependency Injection in Magento 2 is a design pattern used to manage class dependencies. Instead of creating objects directly inside a class, dependencies are injected through the constructor using Magento’s Object Manager.
Magento uses DI to improve code modularity, maintainability, and testability. All dependency configurations are defined in di.xml.
What is the Object Manager in Magento 2?
The Object Manager is Magento’s dependency injection container responsible for creating objects, resolving dependencies, and managing object lifecycle.
Developers should avoid using the Object Manager directly in production code. Instead, dependencies should be injected through constructors.
What is the difference between Plugin, Preference, and Observer?
| Feature | Plugin | Preference | Observer |
|---|---|---|---|
| Purpose | Modify public methods | Override class implementation | React to events |
| Execution | Before / After / Around method | Replace class | Triggered by events |
| Risk | Safe | High conflict risk | Safe |
| Use Case | Extend method behavior | Replace core logic | Handle system events |
What is the difference between Block and ViewModel?
| Feature | Block | ViewModel |
|---|---|---|
| Purpose | Connects layout and template | Provides data to templates |
| Logic | Contains presentation logic | Business logic provider |
| Usage | Traditional Magento approach | Recommended modern approach |
| Testability | Less testable | More testable |
What is Full Page Cache (FPC) in Magento 2?
Full Page Cache stores fully rendered HTML pages so Magento does not need to rebuild them for every request.
Magento supports two types of FPC:
- Built-in Cache (File-based)
- Varnish Cache (Recommended for production)
Benefits:
- Improves page load speed
- Reduces server load
- Enhances scalability
What are Extension Attributes?
Extension attributes allow developers to extend data interfaces without modifying core Magento code.
They are commonly used to add custom fields to API responses such as Product, Order, or Customer entities.
Extension attributes are defined in extension_attributes.xml.
What is the purpose of sequence in module.xml?
The sequence tag defines module load order.
It ensures that a module loads after another module when dependencies exist.
(File: app/code/VendorName/ModuleName/etc/module.xml)
This ensures the custom module loads after the Catalog module.
What are Schema and Data Patches?
Schema patches are used to modify database structure such as creating tables or columns.
Data patches are used to insert or update data in database tables.
- SchemaPatchInterface → Database structure changes
- DataPatchInterface → Database data changes
They replaced the old InstallSchema and UpgradeSchema scripts starting from Magento 2.3.
What are Proxies in Magento 2?
A Proxy is a lazy-loading design pattern used to delay the creation of heavy objects until they are actually needed.
Magento automatically generates proxy classes to improve performance when working with expensive dependencies.
Example:
What is Message Queue in Magento 2?
Message Queue enables asynchronous communication between different parts of the Magento system.
Instead of processing tasks immediately, messages are placed into a queue and processed later by consumers.
Magento supports:
- RabbitMQ
- MySQL queue
It is used for background processing such as bulk operations, inventory updates, and email sending.
What is the purpose of RequireJS in Magento 2?
RequireJS is used to manage JavaScript modules and dependencies.
Magento uses the AMD (Asynchronous Module Definition) pattern to load JavaScript files only when needed.
This improves frontend performance and prevents JavaScript conflicts.
Best Tips for Magento 2 Certification Preparation
- Understand Magento architecture deeply.
- Practice writing custom modules.
- Learn Dependency Injection and Service Contracts.
- Study GraphQL, REST APIs, and Message Queues.
- Understand caching, indexing, and performance optimization.
- Practice Magento CLI commands.