Extension Attribute in Magento 2

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Extension Attribute in Magento 2

Overview

  1. What is extension attributes in magento 2

  2. How does extension attributes work?

  3. How to use extension attributes in custom function in magento 2 ?

What is Extension Attributes ? Why do we need to use it?

  • Magento has many existing entities : customer, catalog_product, order, customer_address, quote, tax, promotion…
  • Some Entities like customer , catalog_product, customer_address are Entity-Attribute-Value (EAV) can add more information  using custom attribute (by program or merchant) easy to add more.
  • But some entities are not EAV. In magento 1, we need to add new column in existing tables for new information field => hard to control with version publish after
  • Extension attributes is another way  to add more information for existing entities (not EAV and EAV entities)
  • EAV entities can also using it in some complexible case.

How to use Extension Attributes ?

  • Find entity data want to add custom information . Example product Magento\Catalog\Api\Data\ProductInterface 
  • Entity need to implement extension attribute : Magento\Framework\Api\ExtensibleDataInterface and must define getExtensionAttributes() and setExtensionAttributes(*ExtensionInterface param)

Extension Attributes

  • Create define module’s Extension attributes : 
  • Find the point need to set extension attribute and save info to custom field in existing entity. Can use plugin or events for it 

How does Extension Attribute work?

  • Existing entity has setter and getter for extension attribute:
  • Extension attribute entity automatic generated in ‘generated’ folder, after config it in module need ro remove this folder to apply the change 
  • Example for product entity: Magento\Catalog\Api\Data\ProductExtension
  • If entity of Extension attribute have not created in generated folder function getExtensionAttributes() return null => need to create Extension attribute entity and set it setExtensionAttributes(ExtensionInterface param)

You can read more here