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How design the service classes?

 
Greenhorn
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I've started on a simple Spring Diary application that uses JPA and Hibernate for ORM.
I have a couple of models that depend on each other. For instance a User can have many Days which can have many Notes. So I created a service-class for each model. But when I want to create a Day I need access to the corresponding User object that must be set. I don't want to have multiple service classes injected in one controller. That feels bad somehow. Is it bad?

My question is basically: What is the best approach when designing service classes for Spring? Should I just put it all in one service class and persist or merge the User when I want to save my changes? That feels so wrong! I want every class to do one thing for ease of maintainability. One big bloated service class is harder to understand and maintain is my opinion. Should I have service classes that call other service classes? Should I start with the models or the use cases or is there some other approach?

I'm surprised that I can't find any examples on how to design this crucial part of the application.
 
Ranch Hand
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Why you are using Hibernate and JPA both for Persistance ?
 
Ranch Hand
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You should have only UserRespository. User is an aggregate root.
 
Hong Anderson
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kri shan wrote:Why you are using Hibernate and JPA both for Persistance ?


JPA is specification/set of interfaces, Hibernate EntityManager is an implementation of JPA.
 
Daniel Näslund
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Kengkaj Sathianpantarit wrote:You should have only UserRespository. User is an aggregate root.



Thank you for your quick feedback! That makes sense when I think about it. I'll go with a UserRepository.

 
Hong Anderson
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Daniel Näslund wrote:

Kengkaj Sathianpantarit wrote:You should have only UserRespository. User is an aggregate root.



Thank you for your quick feedback! That makes sense when I think about it. I'll go with a UserRepository.


That's okay. Whenever you have time, I recommend to read Domain-Driven Design book.
 
ranger
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Kengkaj Sathianpantarit wrote:

Daniel Näslund wrote:

Kengkaj Sathianpantarit wrote:You should have only UserRespository. User is an aggregate root.



Thank you for your quick feedback! That makes sense when I think about it. I'll go with a UserRepository.


That's okay. Whenever you have time, I recommend to read Domain-Driven Design book.



A great book, and a great recommendation.

Mark
 
Don't get me started about those stupid light bulbs.
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