使用CrudRepository的保存

Question

Using

org.springframework.data.repository.CrudRepository
<S extends T> S save(S entity);

What is the difference between these two:

entity = crudRepository.save(entity)
crudRepository.save(entity)

Re-referencing the variable to the save()'s return value seems unnecessary.

Answer 1

The snippet entity = crudRepository.save(entity) is used when you want to get back the saved entity to perform further operations depending on it.

The documentation reads:

Saves a given entity. Use the returned instance for further operations as the save operation might have changed the entity instance completely.

Answer 2

entity = crudRepository.save(entity)

Allow you to get back the id generated if you save a new entity.