azhar-azad/employee-crud-demo

A simple Spring-boot REST API CRUD demo application

Commit Versions:

v1: Use EntityManager but leverage native Hibernate API

v2: Use EntityManager and standard JPA API

v3: Spring Data JPA

v2 Insights: Benefits of JPA, JPA vs Native Hibernate Methods

Benefits

• By having a standard API, you are not locked to vendor's implementation
• Maintain portable, flexible code
• Can theoretically switch vendor implementations
• If vendor ABC stops supporting their product, switch to vendor XYZ without vendor lock in

Comparison

• Create/save new entity:

  Native Hibernate method: session.save()

  JPA method: entityManager.persist()

• Retrieve entity by id

  Native Hibernate method: session.get()/load()

  JPA method: entityManager.find()

• Retrieve list of entities

  Native Hibernate method: session.createQuery()

  JPA method: entityManager.createQuery()

• Save or update entity

  Native Hibernate method: session.saveOrUpdate()

  JPA method: entityManager.merge()

• Delete entity

  Native Hibernate method: session.delete()

  JPA method: entityManager.remove()

v3 Insights: Benefits of Spring Data JPA, JpaRepository

Benefits

• Create a DAO and just plug in your entity type and primary key
• Spring will give you CRUD implementation for FREE ... like MAGIC!!
• Helps to minimize boiler-plate DAO code (Approx. more than 70%).

JpaRepository

• Spring Data JPA provides the interface: JpaRepository.
• Exposes methods (some by inheritance by parents).
• Methods: findAll(), findById(id), save(entity), deleteById(id), others...

Advanced Features

• Extending and adding custom queries with JPQL.
• Query Domain Specific Language (Query DSL)
• Defining custom methods (low-level coding)