MAIN.md

Quick start

1. In addition to spring-data-jpa, add the library dependency :

   <dependency>
       <groupId>com.cosium.spring.data</groupId>
       <artifactId>spring-data-jpa-entity-graph</artifactId>
       <version>${spring-data-jpa-entity-graph.version}</version>
   </dependency>

2. In your Spring configuration, set the repository factory bean class to EntityGraphJpaRepositoryFactoryBean :

   @Configuration
   @EnableJpaRepositories(repositoryFactoryBeanClass = EntityGraphJpaRepositoryFactoryBean.class)
   public class DataRepositoryConfiguration {
       //...
   }

3. Make sure your repositories extend the Spring Data standard ones or the library provided repositories:

• EntityGraphJpaRepository which is equivalent to standard JpaRepository
• EntityGraphJpaSpecificationExecutor which is equivalent to standard JpaSpecificationExecutor
• EntityGraphQuerydslPredicateExecutor which is equivalent to standard QuerydslPredicateExecutor
• EntityGraphCrudRepository which is equivalent to standard CrudRepository
• EntityGraphPagingAndSortingRepository which is equivalent to standard PagingAndSortingRepository
• EntityGraphQueryByExampleExecutor which is equivalent to standard QueryByExampleExecutor

Basic Usage

Let's consider the following entities and repository :

@Entity
public class Brand {
    @Id
    private long id = 0;
    private String name;
    //...
}

@NamedEntityGraphs(value = {
    @NamedEntityGraph(name = "Product.brand", attributeNodes = {
        @NamedAttributeNode("brand")
    })
})
@Entity
public class Product {
    @Id
    private long id = 0;
    private String name;
    @ManyToOne(fetch = FetchType.LAZY)
    private Brand brand;
    //...
}	

public interface ProductRepository extends EntityGraphJpaRepository<Product, Long> {
    List<Product> findByName(String name, EntityGraph entityGraph);
}

You can pass the entity graph to the findByName method :

// This will apply 'Product.brand' named EntityGraph to findByName
productRepository.findByName("MyProduct", EntityGraphs.named("Product.brand"));

Or to the findOne method :

// This will apply 'Product.brand' named EntityGraph to findOne
productRepository.findById(1L, EntityGraphs.named("Product.brand"));

Or any method you like.

You can also pass a dynamically built EntityGraph by using DynamicEntityGraph, it's also accessible through a helper method:

productRepository.findById(1L, EntityGraphUtils.fromAttributePaths("brand", "maker"));

This is similar to Spring's ad-hoc attribute paths, and equivalent to writing this in your repository's interface:

@EntityGraph(attributePaths = { "brand", "maker" })
Product findById(Long id);

Default EntityGraph

For an Entity, you can define its default EntityGraph.
An Entity default EntityGraph will be used each time the Entity repository method is called without EntityGraph.

A default EntityGraph name must end with .default.

@NamedEntityGraphs(value = {
    @NamedEntityGraph(name = "Product.default", attributeNodes = {
        @NamedAttributeNode("brand")
    })
})
@Entity
public class Product {
    @Id
    private long id = 0;
    private String name;
    @ManyToOne(fetch = FetchType.LAZY)
    private Brand brand;
    //...
}	

// This call will make use of "Product.default" EntityGraph.
productRepository.findById(1L);