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我正在努力探索JPA 2.1的新功能， EntityGraph功能通過使用產品，採購訂單和訂單項目之間的樣本關係進行樣本CRUD操作。帶有提示和命名查詢的Jpa實體圖形
下面我主做豆腐的代碼，我定義了一個命名查詢檢索所有數據，以及實體圖形
@Entity
@Table(name = "purchase_order")
@NamedQueries({
@NamedQuery(name = "Order.findAll", query = "SELECT o FROM Order o")})
@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>();
... getter and setter methods
我想打電話給命名查詢和圖形從DAO方法我已經爲下
public List<Order> getOrderDetails() {
return (List<Order>) entityManager.createNamedQuery("Order.findAll").setHint("javax.persistence.loadgraph",
entityManager.getEntityGraph("graph.Order.items")).getResultList();
}
雖然數據庫包含許多行，雖然我試圖改變提示調用DAO方法的結果返回零指數在「javax.persistence.fetchgraph」和「javax.persistence.loadgraph」之間請指教。