The problem of Data class in using JPA Entity in Kotlin

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 When I wrote this test, I expected that "DataIntegrityViolationException" is thrown.





Since I put @NaturalId in email, it seemed that there was no problem.















When I debugged to find out what the problem was, the member objects were successfully saved even though they had same email value.









I found out it was from me poorly understanding how it works when using data class with JPA entity.

This is the link: https://github.com/spring-guides/tut-spring-boot-kotlin#persistence-with-jpa

Since data class creates automatically equals/hashCode, data class's equal compares all the filed. Therefore, id value was different so it recognized they were different entities even though they were same entity.

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