# ORM-hibernate

## ORM - object relational mappers

A pattern that allows the use of a mapper to convert between code (ie java) to database language(ie sql)

### Disadvantages of using orms

* Close coupling of data and business layer
* Lack of control in how ORM implements SQL
* <https://completedeveloperpodcast.com/episode-38/>
* <https://completedeveloperpodcast.com/episode-111/>
* <https://wozniak.ca/blog/2014/08/03/1/index.html?utm\\_source=tuicool\\&amp%3Butm\\_medium=referral>
*

#### Links

* <https://blog.oio.de/2016/05/12/orm-vs-sql-when-should-i-use-a-sql-centric-persistence-layer/>
* <https://www.yegor256.com/2014/12/01/orm-offensive-anti-pattern.html>

### Benefits

#### Links

* <https://dev.to/kirekov/junit-5-link-tests-with-task-tracker-issues-2fif>

### Links

* <https://en.wikipedia.org/wiki/Object-relational\\_mapping>
* <https://medium.com/@krzychukosobudzki/repository-design-pattern-bc490b256006>
* <http://blog.sapiensworks.com/post/2014/06/02/The-Repository-Pattern-For-Dummies.aspx>

## Hibernate

A popular ORM for java.

* <https://thoughts-on-java.org/hibernate-getting-started/>

### Object mapping

* <https://thorben-janssen.com/object-mapper-dto/>
  * Using entities which is linked to ORM (JPA/hibernate) and mapping to a DTO which is independent
  * There are libraries that does this
  * Entities have overheader, while DTO dont
  * DTO are better for separating concerns between business logic and database impl
  * mapping libraries cause DTO to have downsides of entities