kotlin-spring-jpa-examples

• playground for kotlin + spring-boot + bean-validation + jpa + hibernate + querydsl
• realworld examples (just a little simplified): check api.realestate

status:

• its an active playground ,therefore in progress ...

requirements

• postgres

create an example db

$ make db.local.create 

additional resources

bean validation

• https://stackoverflow.com/questions/44320678/jsr-349-bean-validation-for-spring-restcontroller-with-spring-boot
• http://apprize.info/javascript/wrox/16.html
• https://github.com/gothinkster/kotlin-spring-realworld-example-app/blob/master/src/main/kotlin/io/realworld/ApiApplication.kt
• https://github.com/arawn/kotlin-spring-example/blob/master/src/main/kotlin/org/ksug/forum/web/ForumRestController.kt

findings

hibernate:

• if you have to use if for whatever reason, check the logs ;) ...

hibernate: immutable data class as @Entity

• in jpa/hibernate context it gets proxied by cglib & bean validation works
• entity.copy() -> triggers init() method, if there is one

hibernate: auditing

• Auditing classes (Listeners) are no spring beans
• @inject will not work out-of-the-box
• thefore its pretty useless

jetbrains gradle plugin:

• https://github.com/JetBrains/kotlin/blob/master/libraries/tools/kotlin-gradle-plugin/Module.md

querydsl: is awesome :)

• https://github.com/JetBrains/kotlin-examples/blob/master/gradle/kotlin-querydsl/build.gradle

• https://github.com/eugenp/tutorials/tree/master/querydsl

• example implementation:

    com.example.demo.api.realestate.PropertiesCrudController.search()
  

elasticsearch

• https://www.mkyong.com/spring-boot/spring-boot-spring-data-elasticsearch-example/
• spring-data-elasticsearch: dependency hell:
  • boot 1.5.* with spring-data-elasticsearch does not work with es 5.5
  • es 5.5 requires spring-data-elasticsearch 2.* (boot 2.*)
  • using es transportclient (native protocol) is not recommended by es
  • es recommends using rest-api - which is aware of future versions of es
  • es is currently working on a high level restapi client that should make things easy
  • most cloud providers (hosted-es-as-a-service) just allow using rest api
  • several issues related to jackson-json serialization (e.g.: supports JodaTime but not Java 8 Time Api out-of-the-box)