客户

Question

我有两个表，一个是customer，另一个是customerDepartment。客户与customerDepartment有一对多的关系。

我有一个特定的搜索条件，我需要搜索部门名称，如果等于，则需要检索所有客户部门行，包括客户。

这就是我试图得到的结果

public interface CustomerRepository extends JpaRepository<Customer,Integer>{


    @Query(value="select DISTINCT c from Customer c left join c.custDept cd where cd.deptName like %?1% ")
    Page<Customer> findByName(String name, Pageable pageable);

}

客户

@Entity
@Table(name="customer")
public class Customer implements Serializable{


    private static final long serialVersionUID = 1L;

    @Id
    @Column(name= "customer_no",updatable = false, nullable = false)
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private int customerNo;

    @Column(name= "customer_name")
    private String customerName;

    @Column(name= "industry")
    private String industry;

     @JsonManagedReference
     @OneToMany(mappedBy = "customer", cascade = CascadeType.ALL, 
     fetch=FetchType.LAZY)
     private Set<CustomerDepartment> custDept;

}

客户部门：

@Entity
@Table(name = "customer_department")
public class CustomerDepartment implements Serializable{

    private static final long serialVersionUID = 1L;

    @Id
    @Column(name = "dept_id",updatable = false, nullable = false)
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private int depId;

    @Column(name = "dept_name")
    private String deptName;

    @Column(name = "primary_contact")
    private String primaryContact;

      @JsonBackReference
      @ManyToOne(fetch=FetchType.LAZY)
      @JoinColumn(name = "customer_no", nullable = false)
      private Customer customer;

}

当我搜索DepartmentName = it时，上述JPA查询返回以下结果

{
    "content": [
        {
            "customerNo": 33,
            "customerName": "Test1",
            "industry": "High-Tech",
            "country": "Australia",
            "state": "Sa-Jose",
            "city": "Sydney",
            "custDept": [
                {
                    "depId": 34,
                    "deptName": "It",
                    "primaryContact": "Banglore,Kormangala",
                },
                {
                    "depId": 35,
                    "deptName": "sales",
                    "primaryContact": "Banglore,Kormangala",

                }
            ]
        }
    ]
}

我期望的更像是

{
    "content": [
        {
            "customerNo": 33,
            "customerName": "Test1",
            "industry": "High-Tech",
            "country": "Australia",
            "state": "Sa-Jose",
            "city": "Sydney",
            "custDept": [
                {
                    "depId": 34,
                    "deptName": "It",
                    "primaryContact": "Banglore,Kormangala",
                }
            ]
        }
    ]
}

如果这在JPA中是不可能的，有什么办法可以做到这一点。感谢您的帮助

Answer 1

是的，我是这样认为的。我评论说：“我认为您的查询是可以的，但是当将结果编组为JSON时，将检索所有关联部门。您应在编组之前查看sql输出并调试并检查查询结果，以了解是否案子。”我继续研究它，我或多或少是正确的。

问题是您没有获取查询的custDept集合，因此当客户被编组以获取其余响应时，将执行附加查询以获取值，附加查询仅查询所有内容。

2019-05-25 14：29：35.566调试63900 --- [nio-8080-exec-2] org.hibernate.SQL：选择不同的customer0_.customer_no作为customer1_0_，customer0_.customer_name作为customer2_0_，customer0_.industry作为来自客户customer0_的行业3_0_，从左外部加入了customer0_.customer_no = custdept1_.customer_no上的customer_department custdept1_，其中custdept1_.dept_name喜欢吗？限制？

2019-05-25 14：29：35.653调试63900 --- [nio-8080-exec-2] org.hibernate.SQL：选择custdept0_.customer_no作为customer4_1_0_，custdept0_.dept_id作为dept_id1_1_0_0，custdept0_.dept_id作为customer4_1_0_ dept_id1_1_1_1，custdept0_.customer_no作为customer4_1_1_，custdept0_.dept_name作为dept_nam2_1_1_，custdept0_.primary_contact作为primary_3_1_1_来自customer_department custdept0_，其中custdept0_.customer_no =？

如果仅需要查询提供的内容，则需要进行提取，以便custDept集在被编组之前被初始化。您的查询还存在其他问题。您应该使用sql参数:deptName并声明它，并且应该提供countQuery，因为您要返回Page。

public interface CustomerRepository extends JpaRepository<Customer,Integer>{
    @Query(value="select DISTINCT c from Customer c left join fetch c.custDept cd where cd.deptName like %:deptName% ", 
            countQuery = "select count ( DISTINCT c ) from Customer c left join c.custDept cd where cd.deptName like %:deptName% ")
    public Page<Customer> findByName(@Param("deptName") String deptName, Pageable pageable);

为我工作。现在只执行原始查询，结果正确。

{
"content": [
    {
        "customerNo": 1,
        "custDept": [
            {
                "deptName": "it"
            }
        ]
    }
],

最后请注意，根据春季文档，最好将Integer用于实体中的@Id。

如何通过JPA从联接的第二张表中检索特定行

客户

客户部门：

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