JPQL - 使用过滤器连接查询

Question

I have the entitys:

First

@Entity
@Getter
@Setter
@NoArgsConstructor
public class Technic implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    private String gosNumber;

    private String invNumber;

    private String shassisNumber;

    private String engineNumber;

    @Column(length = 100)
    private String yearOfMake;

    @ManyToOne
    private Farm farm;

    @JsonManagedReference
    @ManyToOne
    private TechGroup techGroup;

    @JsonManagedReference
    @ManyToOne
    private TechType techType;

    @JsonManagedReference
    @ManyToOne
    private TechMark techMark;

    @JsonIgnore
    @CreationTimestamp
    @Column(name = "creation_date", updatable = false)
    private LocalDateTime createdDate;

    @JsonIgnore
    @Column(name = "updated_date")
    @UpdateTimestamp
    private LocalDateTime updatedDate;

    @JsonIgnore
    @Column(columnDefinition = "Bool default false")
    private Boolean isDel;


    @JsonManagedReference
    @OneToMany(mappedBy = "technic")
    private List<TechnicStatus> technicStatusList = new ArrayList<>();

    public List<TechnicStatus> getTechnicStatusList() {
        return technicStatusList;
    }

    public void setTechnicStatus(TechnicStatus technicStatus) {
        this.technicStatusList = new ArrayList<>();
        this.technicStatusList.add(technicStatus);
    }

Second:

@Entity
@Getter
@Setter
@NoArgsConstructor
public class TechnicStatus implements Serializable  {



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

    @JsonBackReference
    @ManyToOne
    private Technic technic;

    @JsonManagedReference
    @ManyToOne
    private Status status;

    private Boolean isGarantia;

    private Boolean isLizing;

    private LocalDate visitedDate;

    private LocalDate notWorkDate;

    private String description;

    @JsonIgnore
    private boolean isActive;

    @JsonIgnore
    @CreationTimestamp
    @Column(name = "creation_date", updatable = false)
    private LocalDateTime createdDate;
}

I want to get result from my db which contains the List in each object Technic i have List technicStatusList = new ArrayList<>() in which i want to have a TechnicStatus only with value is isActive=true.

For this i right same JPQL query:

TypedQuery<Technic> query = em.createQuery("Select t  from Technic t join TechnicStatus ts on t.id = ts.technic.id where t.isDel=false and ts.isActive=true and t.farm.id=:farmId order by t.techGroup.name, t.techType.name, t.techMark.name", Technic.class);

But get a result containing TechnicStatus, which returns a TechnicStatus with true and false (TechnicStatus.isActive=true, TechnicStatus.isActive=false).

I want to get result as this native query:

SELECT 
    *
FROM
    technic
        JOIN
    technic_status ON technic.id = technic_status.technic_id
WHERE
    technic.is_del = FALSE
        AND technic_status.is_active = TRUE
        AND technic.farm_id = 1722

Answer 1

The List of TechnicalStatus associated with a Technic will always be the complete list as defined by your mappings.

Essentially then you have 2 options. If you are only ever interested in TechnicalStatus with a status of Active then you can use the non-portable, Hibernate specific @Where clause on the association.

@JsonManagedReference
@OneToMany(mappedBy = "technic")
@Where("active = 1")
private List<TechnicStatus> technicStatusList = new ArrayList<>();

https://dzone.com/articles/hibernate-where-clause

Otherwise all you do is return a List of TechnicalStatus from query method which is not what you want but is all you have.

Answer 2

Its not possible to filter related collection in query conditions. You can get it by doing select on TechnicalStatus: select ts from TechnicStatus ts join Technic t where ...

Other thing I noticed:

You are overwriting list of existing statuses when adding new one:

public void setTechnicStatus(TechnicStatus technicStatus) {
     this.technicStatusList = new ArrayList<>();
     this.technicStatusList.add(technicStatus);
}

Initialize technicStatusList in field declaration. Method in Technic for adding:

public void addTechnicStatus(TechnicStatus technicStatus) {
    getTechnicStatusList().add(technicStatus);
    technicStatus.setTechnic(this);
}

Other thing I noticed:

When using join don't use on t.id = ts.technic.id . JPA will create correct native SQL just when you write: join TechnicStatus ts WHERE ...

Answer 3

Using join fetch should solve the issue, this would force the query to run eagerly all at once and only bring back the records that match the where clause. so your query would be:

TypedQuery<Technic> query = em.createQuery("Select t from Technic t join fetch TechnicStatus ts where t.isDel=false and ts.isActive=true and t.farm.id=:farmId order by t.techGroup.name, t.techType.name, t.techMark.name", Technic.class);