JPA 2.1 Entity Graph - Part 2: Define lazy/eager loading at runtime (http://www.thoughts-on-java.org/2014/04/jpa-21-entity-graph-part-2-define.html)

defineGraph.java

EntityGraph<Order> graph = this.em.createEntityGraph(Order.class);
graph.addAttributeNodes("items");

Map<String, Object> hints = new HashMap<String, Object>();
hints.put("javax.persistence.loadgraph", graph);

this.em.find(Order.class, orderId, hints);

defineSubGraph.java

EntityGraph<Order> graph = this.em.createEntityGraph(Order.class);
Subgraph<OrderItem> itemGraph = graph.addSubgraph("items");
itemGraph.addAttributeNodes("product");

Map<String, Object> hints = new HashMap<String, Object>();
hints.put("javax.persistence.loadgraph", graph);

return this.em.find(Order.class, orderId, hints);

Order.java

@Entity
@Table(name = "purchaseOrder")
@NamedEntityGraph(name = "graph.Order.items", 
               attributeNodes = @NamedAttributeNode(value = "items", subgraph = "items"), 
               subgraphs = @NamedSubgraph(name = "items", attributeNodes = @NamedAttributeNode("product")))
public class Order implements Serializable {

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id", updatable = false, nullable = false)
   private Long id = null;
   @Version
   @Column(name = "version")
   private int version = 0;

   @Column
   private String orderNumber;

   @OneToMany(mappedBy = "order", fetch = FetchType.LAZY)
   private Set<OrderItem> items = new HashSet<OrderItem>();

   ...

OrderItem.java

@Entity
public class OrderItem implements Serializable
{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id", updatable = false, nullable = false)
   private Long id = null;
   @Version
   @Column(name = "version")
   private int version = 0;

   @Column
   private int quantity;

   @ManyToOne
   private Order order;

   @ManyToOne(fetch = FetchType.LAZY)
   private Product product;

Product.java

@Entity
public class Product implements Serializable
{

   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   @Column(name = "id", updatable = false, nullable = false)
   private Long id = null;
   @Version
   @Column(name = "version")
   private int version = 0;

   @Column
   private String name;

server.log

2014-04-07 20:08:15,260 DEBUG [org.hibernate.loader.plan.build.spi.LoadPlanTreePrinter] (default task-2) LoadPlan(entity=blog.thoughts.on.java.jpa21.entity.graph.model.Order)
    - Returns
       - EntityReturnImpl(entity=blog.thoughts.on.java.jpa21.entity.graph.model.Order, querySpaceUid=, path=blog.thoughts.on.java.jpa21.entity.graph.model.Order)
          - CollectionAttributeFetchImpl(collection=blog.thoughts.on.java.jpa21.entity.graph.model.Order.items, querySpaceUid=, path=blog.thoughts.on.java.jpa21.entity.graph.model.Order.items)
             - (collection element) CollectionFetchableElementEntityGraph(entity=blog.thoughts.on.java.jpa21.entity.graph.model.OrderItem, querySpaceUid=, path=blog.thoughts.on.java.jpa21.entity.graph.model.Order.items.)
    - QuerySpaces
       - EntityQuerySpaceImpl(uid=, entity=blog.thoughts.on.java.jpa21.entity.graph.model.Order)
          - SQL table alias mapping - order0_
          - alias suffix - 0_
          - suffixed key columns - {id1_2_0_}
          - JOIN (JoinDefinedByMetadata(items)) :  -> 
             - CollectionQuerySpaceImpl(uid=, collection=blog.thoughts.on.java.jpa21.entity.graph.model.Order.items)
                - SQL table alias mapping - items1_
                - alias suffix - 1_
                - suffixed key columns - {order_id4_2_1_}
                - entity-element alias suffix - 2_
                - 2_entity-element suffixed key columns - id1_0_2_
                - JOIN (JoinDefinedByMetadata(elements)) :  -> 
                   - EntityQuerySpaceImpl(uid=, entity=blog.thoughts.on.java.jpa21.entity.graph.model.OrderItem)
                      - SQL table alias mapping - items1_
                      - alias suffix - 2_
                      - suffixed key columns - {id1_0_2_}

2014-04-07 20:08:15,260 DEBUG [org.hibernate.loader.entity.plan.EntityLoader] (default task-2) Static select for entity blog.thoughts.on.java.jpa21.entity.graph.model.Order [NONE:-1]: select order0_.id as id1_2_0_, order0_.orderNumber as orderNum2_2_0_, order0_.version as version3_2_0_, items1_.order_id as order_id4_2_1_, items1_.id as id1_0_1_, items1_.id as id1_0_2_, items1_.order_id as order_id4_0_2_, items1_.product_id as product_5_0_2_, items1_.quantity as quantity2_0_2_, items1_.version as version3_0_2_ from purchaseOrder order0_ left outer join OrderItem items1_ on order0_.id=items1_.order_id where order0_.id=?