https://github.com/mtumilowicz/spring-data-getone

The main goal of this project is to show how getOne works internally.
https://github.com/mtumilowicz/spring-data-getone

jpa spring-data spring-data-jpa

Last synced: about 1 month ago
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The main goal of this project is to show how getOne works internally.

• Host: GitHub
• URL: https://github.com/mtumilowicz/spring-data-getone
• Owner: mtumilowicz
• Created: 2018-08-10T19:03:56.000Z (almost 8 years ago)
• Default Branch: master
• Last Pushed: 2018-08-24T22:13:55.000Z (almost 8 years ago)
• Last Synced: 2025-10-20T02:15:44.027Z (9 months ago)
• Topics: jpa, spring-data, spring-data-jpa
• Language: Java
• Homepage:
• Size: 77.1 KB
• Stars: 2
• Watchers: 0
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
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# spring-data-getone

The main goal of this project is to show how `getOne` works internally.

# preface

According to JPA specification, we have two methods:

* `EntityManager.find()` - query the database.

* `EntityManager.getReference()` - load proxy (no database query), 

    throws `EntityNotFoundException` if entity doesn't exist in the database 

    (when synchronization with the database occurs).

    

# spring data

* `Optional findById(ID id)` - eager loading (internally `EntityManager.find()`)

* `T getOne(ID id)` - lazy loading (internally `EntityManager.getReference()`)

# project description

We enable query logging (`application.properties`):

```

spring.jpa.properties.hibernate.show_sql=true

```

and in `AppRunner` we simulate basic behaviour.

# remarks

If you use `getOne` it loads proxy, but at first reference to any field - 

provider loads the actual entity from database - so you have to still be

in the persistence context.

# tests

**Coverage**: `96%`