JPA 2.1 Hibernate中的NamedSubgraph忽略了子類

Question

我正在使用Hibernate 4.3.8.FINAL並且具有以下模型，其中Department有許多Employees，Employee可以是Manager。

員工實體：

@Entity
@Table(name = "employee", schema = "payroll")
@Inheritance(strategy = InheritanceType.JOINED)
public class Employee
{
    @Id
    private Long id;

    @Basic(optional = false)
    @Column(name = "name")
    private String name;

    @JoinColumn(name = "department_id", referencedColumnName = "id")
    @ManyToOne(optional = false, fetch = FetchType.LAZY)
    private Department department;
}

經理實體：

@Entity
@Table(name = "manager", schema = "payroll")
@Inheritance(strategy = InheritanceType.JOINED)
@PrimaryKeyJoinColumn(name = "employee_id", referencedColumnName = "id")
public class Manager extends Employee
{
    @Basic(optional = false)
    @Column(name = "car_allowance")
    private boolean carAllowance;
}

部門實體：

@NamedEntityGraph(
        name = "Graph.Department.FetchManagers",
        includeAllAttributes = false,
        attributeNodes = {
                @NamedAttributeNode(value = "name"),
                @NamedAttributeNode(value = "employees", subgraph = "FetchManagers.Subgraph.Managers")
        },
        subgraphs = {
                @NamedSubgraph(
                        name = "FetchManagers.Subgraph.Managers",
                        type = Employee.class,
                        attributeNodes = {
                                @NamedAttributeNode(value = "name")
                        }
                ),
                @NamedSubgraph(
                        name = "FetchManagers.Subgraph.Managers",
                        type = Manager.class,
                        attributeNodes = {
                                @NamedAttributeNode(value = "carAllowance"),
                        }
                )
        }
)
@Entity
@Table(name = "department", schema = "payroll")
public class Department
{

    @Id
    private Long id;

    @Basic(optional = false)
    @Column(name = "name")
    private String name;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "department", fetch = FetchType.LAZY)
    private Set<Employee> employees;
}

如部門實體所示，我正在嘗試創建一個加載所有員工的@NamedSubgraph，並且還要獲取Manager.carAllowance。 但是我收到以下錯誤：

Unable to locate Attribute  with the the given name [carAllowance] on this ManagedType [com.nemea.hydra.model.test.Employee]

根據我的理解，@ NamedSubgraph.type應該用於指定要獲取的實體子類屬性。 是否有可能Hibernate忽略了@NamedSubgraph注釋的type = Manager.class屬性，或者我錯過了什么？

Answer 1

這可能是休眠4.3.8.FINAL的缺陷，如如的EclipseLink 2.5.1不拋出異常時， subgraphs屬性被使用。

無論如何，當你在Manager類型的情況下指定subclassSubgraphs而不是subclass時它應該工作，即：

@NamedEntityGraph(
    name = "Graph.Department.FetchManagers", 
    includeAllAttributes = false,
    attributeNodes = {
        @NamedAttributeNode(value = "name"),
        @NamedAttributeNode(value = "employees", subgraph = "FetchManagers.Subgraph.Managers")
    },
    subgraphs = {
        @NamedSubgraph(
            name = "FetchManagers.Subgraph.Managers",
            type = Employee.class,
            attributeNodes = {
                @NamedAttributeNode(value = "name")
            }
        )
    },
    subclassSubgraphs = {
        @NamedSubgraph(
            name = "FetchManagers.Subgraph.Managers",
            type = Manager.class,
            attributeNodes = {
                @NamedAttributeNode(value = "carAllowance"),
            }
        )
    }
)