Question

我需要帮助解决与EclipseLink 2.5.x提供程序的关系/查询问题。

从ThreePhaseMotorInput到ValidationMessage的关系应该是单向的OneToMany，即每个电机可以有0..n消息，而在Java对象图中，ValidationMessage没有对ThreePhaseMotorInput的引用。

我收到一条错误，即JPA在通过ThreePhaseMotor访问时无法找到属于ValidationMessage类的属性。（见下面的错误文本）

感谢您考虑我的问题！

查询

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;

Answer 1

问题似乎出现在以下查询中：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，即您指定实体及其Java属性的查询。如果您想跳转到其他实体的属性，也必须使用JOIN：m.valMessages.validationMsg不正确，但INNER JOIN m.valMessages msg GROUP BY msg是正确的。

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

Answer 2

您不能将路径表达式与Collection值关联一起使用。

文档说：JPQL Path Expressions

从计算到集合的路径表达式中组合路径表达式在语法上是非法的。

在您的查询中，m.valMessages是非法的，因为它引用了ValidationMessages的集合。

另一方面，m.approvedMotor是合法的，因为它是单值关联。

正如Andrei回应中所建议的那样，您需要修改查询以添加另一个路径表达式：

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

Answer 3

如果要跳转到其他实体的属性，则应使用JOIN。尝试以下JPQL查询

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

JPA无法将状态字段路径解析为有效类型

3 个答案: