java - 使用 JPA 删除实体时出现问题

Question

更新

我的 friend 做了同样的代码，他的代码行正常工作。会是什么呢？我用的是NetBeans 7.0.1，他的是6.9.1。我的 GlassFish 是 3.1，他的是 3.0.1

更新结束

@Inheritance(strategy= InheritanceType.JOINED)
@Entity
@Table(name = "vehicle")
@DiscriminatorColumn(name = "type", discriminatorType = DiscriminatorType.INTEGER)
@NamedQueries({
    @NamedQuery(name = "Vehicle.findAll", query = "SELECT v FROM Vehicle v")})
public class Vehicle implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Integer id;

    @JoinColumn(name = "color_id")
    @ManyToOne(optional = false)
    private Color color;

public Vehicle() {
}

//Getters and Setters

}

---

@Entity
@Table(name = "car")
@DiscriminatorValue("1")
@NamedQueries({
    @NamedQuery(name = "Car.findAll", query = "SELECT c FROM Car c")})
public class Car extends Vehicle implements Serializable {
    private static final long serialVersionUID = 1L;

    @Column(name = "airbag")
    private Boolean airbag;

public Car() {
}

//Getters and Setters

}

当我尝试删除一辆车时，它会抛出异常，并且在 Stacktrace 中有一个 UPDATE 查询，如果我尝试删除，这会很奇怪。

你们知道这里会发生什么吗？

Car car = em.find(Car.class, id);
em.remove(car);

堆栈:

Caused by: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'color_id' cannot be null
Error Code: 1048
Call: UPDATE vehicle SET color_id = ? WHERE (id = ?)
    bind => [2 parameters bound]
Query: DeleteObjectQuery(br.com.something.entity.Vehicle[ id=3 ])
    at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:324)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeDirectNoSelect(DatabaseAccessor.java:840)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeNoSelect(DatabaseAccessor.java:906)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:592)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:535)
    at org.eclipse.persistence.internal.sessions.AbstractSession.basicExecuteCall(AbstractSession.java:1702)
    at org.eclipse.persistence.sessions.server.ClientSession.executeCall(ClientSession.java:253)
    at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:207)
    at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:193)
    at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.updateObject(DatasourceCallQueryMechanism.java:749)

Answer 1

也许您需要关于汽车和颜色之间关系的 CascadeType？