Spring Boot @Autowired with Kotlin in @Service is always null

Question

Currently I try to rewrite my Java Spring Boot Application with Kotlin. I encountered a problem that in all of my classes which are annotated with @Service the depe

Answer 1

I just bumped into exactly same issue - injection worked well, but after adding @Transactional annotation all the autowired fields are null.

My code:

@Service
@Transactional  
open class MyDAO(val jdbcTemplate: JdbcTemplate) {

   fun update(sql: String): Int {
       return jdbcTemplate.update(sql)
   }

} 

The problem here is that the methods are final by default in Kotlin, so Spring is unable to create proxy for the class:

 o.s.aop.framework.CglibAopProxy: Unable to proxy method [public final int org.mycompany.MyDAO.update(...

"Opening" the method fixes the issue:

Fixed code:

@Service
@Transactional  
open class MyDAO(val jdbcTemplate: JdbcTemplate) {

   open fun update(sql: String): Int {
       return jdbcTemplate.update(sql)
   }

}