Adding EntityManager.refresh to All Spring Data Repositories

In my previous post, Access the EntityManager from Spring Data JPA, I showed how to extend a single Spring Data JPA repository to access the EntityManager.refresh method. This post demonstrates how to add EntityManager.refresh to all Spring Data repositories.

Source Code

The first step is to define your interface:

package com.glenware.springboot.repository;

import org.springframework.data.repository.NoRepositoryBean;
import org.springframework.data.repository.Repository;
import org.springframework.data.repository.CrudRepository;

import java.io.Serializable;
import java.util.Optional;

@NoRepositoryBean
public interface CustomRepository<T, ID extends Serializable>
extends CrudRepository<T, ID> {
    void refresh(T t);
}

The key points are:

• @NoRepositoryBean: This prevents an instance of a repository being created.
• Extending the CrudRepository: You need to decide which repository to extend. I'm using CrudRepository, as this was used in the previous post.
• The void refresh method signature is the same as the EntityManager.refresh method.

Implementation

The next step is to implement this interface in a custom repository:

package com.glenware.springboot.repository;

import org.springframework.data.jpa.repository.support.SimpleJpaRepository;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.data.jpa.repository.support.JpaEntityInformation;

import javax.persistence.EntityManager;
import java.io.Serializable;

public class CustomRepositoryImpl<T, ID extends Serializable&gt;
extends SimpleJpaRepository>T, ID> implements CustomRepository<T, ID> {

    private final EntityManager entityManager;

    public CustomRepositoryImpl(JpaEntityInformation entityInformation, 
                                EntityManager entityManager) {
        super(entityInformation, entityManager);
        this.entityManager = entityManager;
    }

    @Override
    @Transactional
    public void refresh(T t) {
        entityManager.refresh(t);
    }
}

The key points are:

• Extend the SimpleJpaRepository repository. The SimpleJpaRepository is the default implementation for CrudRepository.
• The constructor is the SimpleJpaRepository constructor, taking the JpaEntityInformation and EntityManager objects.
• We save a local copy of the EntityManager.
• The refresh method simply calls the EntityManager.refresh method.

The final step is to let Spring Data know that its base class is CustomRepositoryImpl:

package com.glenware.springboot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

import com.glenware.springboot.repository.CustomRepositoryImpl;

@SpringBootApplication
@EnableJpaRepositories(repositoryBaseClass = CustomRepositoryImpl.class)
public class ParkrunpbApplication {
   public static void main(String[] args) {
      SpringApplication.run(ParkrunpbApplication.class, args);
   }
}

Key points:

• EnableJpaRepositories: This annotation enables JPA repositories and will scan com.glenware.springboot by default.
• The repositoryBaseClass attribute is used to let the Spring Data configuration know we are overriding the default base class.

All Together Now

We can then use this repository in our classes so we change our repository from the previous post from CrudRepository to extend CustomRepository:

package com.glenware.springboot.repository;

import com.glenware.springboot.form.ParkrunCourse;

public interface ParkrunCourseRepository 
   extends CustomRepository<ParkrunCourse, Long> {
}

We can now access the EntityManager.refresh method using:

parkrunCourseRepository.refresh( parkrunCourse );

The above code was tested by running it against Spring Boot (1.5.6-Release), which used Spring Data JPA 1.11.6.Release. I can add the code to GitHub if requested

Gotcha’s

One area you need to check is what version of Spring Data JPA you are running for extending repositories. I’ve had to adapt this approach for older repositories, although this is the current method using Spring Data JPA 1.11.6 Release.