存储库上的事务

Question

My controller looks like this :

@RequestMapping(value = "/User", method = RequestMethod.GET)
public @ResponseBody String getUser(@RequestParam long id) {
User user = userService.get(id);
return user.name;
}

Where service looks like this

@Transactional(readOnly = true)
public User getUser(long id) {
  return userRepository.get(id);
}

I hear the mantra transactions on service layer , transaction on service layer ; but would it be so bad to inject the repository directly into controller. After first making the repository transactional - with propagation required so it will create a transaction if not already present ?

Answer 1

This depends on the size of your project and the complexity within it. I feel services work excellent when multiple repositories need to interact.

For example, a BankAccountService needs to use the AccountRepository to debit/credit an account, while it also needs to use the LedgerRepository to record the transaction.

If your simply performing crud operations, I would not hesitate to put the repository in the controller. If your operations are more advanced I would take the service approach. Address your simplest use case and then refactor when more complexity is introduced. Doing a big design up front often violates the "You Ain't Gonna Need It" principle.

Also services are handy when different controllers need to perform the same operation. So if the logic you are creating is controller specific and you do not need to reuse the code, placing the repository in the controller makes sense. If you will need to duplicate the logic within other controllers a service may be a better option, since it will be reusable.