jpa - JPA状态字段路径无法解析为有效类型

在使用EclipseLink 2.5.x提供程序解决关系/查询问题时，我需要帮助。

从ThreePhaseMotorInput到ValidationMessage的关系应该是单向的OneToMany，即每个电动机可以具有0..n消息，并且在Java对象图中ValidationMessage没有对ThreePhaseMotorInput的引用。

我收到一个错误，当通过ThreePhaseMotor访问JPA时，它找不到ValidationMessage类的一部分属性。 （请参见下面的错误文本）

感谢您考虑我的问题！

询问

select msg.validationMsg, COUNT(m.id) from ThreePhaseMotorInput AS m JOIN m.valMessages AS msg GROUP BY msg.validationMsg

错误

 org.eclipse.persistence.exceptions.JPQLException:
Exception Description: Problem compiling [select msg.validationMsg, COUNT(m.id) from ThreePhaseMotorInput AS m JOIN m.valMessages AS msg GROUP BY msg.validationMsg].
[7, 24] The state field path 'msg.validationMsg' cannot be resolved to a valid type.
[71, 84] The collection-valued path 'm.valMessages' cannot be resolved to a valid association field.
[119, 136] The state field path 'msg.validationMsg' cannot be resolved to a valid type.

ThreePhaseMotorInput类

@Entity
@Table(name = "three_phase_motor_input")
public class ThreePhaseMotorInput implements IThreePhaseMotorInput, Serializable {
    private static final long serialVersionUID = 8084370807289186987L;
    @Transient
    private final PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(this);

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Version
    private Integer version;
    private Integer status;
    @Transient
    private Integer numMessages;

    @OneToOne(cascade = CascadeType.ALL, optional = true, targetEntity = UnapprovedThreePhaseMotor.class)
    @JoinColumn(name = "unapproved_id")
    private IThreePhaseMotor unapprovedMotor;

    @OneToOne(cascade = CascadeType.ALL, optional = true, targetEntity = ApprovedThreePhaseMotor.class)
    @JoinColumn(name = "approved_id")
    private IThreePhaseMotor approvedMotor;

    @OneToMany(orphanRemoval = true, cascade = CascadeType  .ALL, fetch = FetchType.LAZY, targetEntity = ValidationMessage.class)
    @JoinColumn(name = "input_id", referencedColumnName = "id", nullable = false)
    @OrderColumn(name = "idx")
    private List<IValidationMessage> valMessages;

ValidationMessage类

@Entity
@Table(name = "validation_message")
public class ValidationMessage implements Serializable, IValidationMessage {
    private static final long serialVersionUID = 8765213112015434057L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Column(name = "record_id")
    private Long recordId;
    @Column(name = "field_name")
    private String fieldName;
    @Column(name = "validation_msg")
    private String validationMsg;
    private Integer status;
    @Column(name = "fail_field")
    private String failField;
    @Column(name = "error_source")
    private Integer errorSource;

最佳答案

问题似乎在以下查询中：select m.approvedMotor, m.valMessages, m.valMessages.validationMsg, count(m.valMessages.id) from ThreePhaseMotorInput m group by m.valMessages.validationMsg。

该查询应该是JPQL查询，即您在其中指定实体及其Java属性的查询。另外，如果要跳转到另一个实体的属性，还必须使用JOIN：m.valMessages.validationMsg不正确，但是INNER JOIN m.valMessages msg GROUP BY msg是正确的。

因此，请尝试以下查询：

select m, COUNT(msg) from ThreePhaseMotorInput AS m LEFT JOIN m.valMessages AS msg GROUP BY msg.validationMsg