Spring Data JPA ManyToOne 查询 null答案

【问题标题】：Spring Data JPA ManyToOne query nullSpring Data JPA ManyToOne 查询 null
【发布时间】：2020-05-26 11:13:39
【问题描述】：

我已经开始学习 Spring Boot，我创建了两个实体 Invoice 和 YearDate

当我尝试按年份（id）搜索时，在我的日志查询中我得到了 null（请参阅日志查询的这一部分）

http://localhost:8080/appapi/invoices/search/findByYearId?year=1

from invoice invoice0_ left outer join year_date yeardate1_ on invoice0_.year_id=yeardate1_.id where yeardate1_.id is null limit?

我也将 Lombok 用于获取器和设置器

这是我所有的类实体、SQL 表和 JpaRepository 接口：

SQL 外键：

KEY `fk_year` (`year_id`),
  CONSTRAINT `fk_year` FOREIGN KEY (`year_id`) REFERENCES `YearDate` (`id`)

YearDate 类：

@Entity
@Table(name="YearDate")
@Data
public class YearDate {

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

    @Column(name = "year_value")
    private String yearValue;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "year")
    private Set<Invoice> invoices;
}

发票类：

@Entity
@Table(name="invoice")
@Data
public class Invoice {

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

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

    @ManyToOne
    @JoinColumn(name = "year_id", nullable = false)
    private YearDate year;

    @Column(name = "description")
    private String description;
}


**And The Invoice Interface:**

@CrossOrigin("http://localhost:4200")
public interface InvoiceRepository extends JpaRepository<Invoice, Long> {

    Page<Invoice> findByYearId(@RequestParam("year") Long id, Pageable page);

}

【问题讨论】：

标签： spring spring-boot spring-data-jpa

【解决方案1】：

为我工作。

尝试在休息控制器中提取调用并记录参数

@GetMapping(value = "/invoices")
  public Page<Invoice> getInvoices(@RequestParam("yearId") Long yearId) {
        Page<Invoice> byYearId = invoiceRepository.findByYearId(yearId, PageRequest.of(0, 10));
        return byYearId;
}


public interface InvoiceRepository extends JpaRepository<Invoice, Long> {

    Page<Invoice> findByYearId(Long id, Pageable page);
}


 @ManyToOne
    @JoinColumn(name = "year_id", nullable = false)
   @JsonIgnoreProperties("invoices")
    private YearDate year;

 @OneToMany(mappedBy = "year")
    @JsonIgnoreProperties("year")
    private Set<Invoice> invoices;

生成的 SQL：

Hibernate: 
    select
        invoice0_.id as id1_0_,
        invoice0_.description as descript2_0_,
        invoice0_.name as name3_0_,
        invoice0_.year_id as year_id4_0_ 
    from
        invoice invoice0_ 
    left outer join
        year_date yeardate1_ 
            on invoice0_.year_id=yeardate1_.id 
    where
        yeardate1_.id=? limit ?
Hibernate: 
    select
        yeardate0_.id as id1_5_0_,
        yeardate0_.year_value as year_val2_5_0_ 
    from
        year_date yeardate0_ 
    where
        yeardate0_.id=?

-> 将@JsonIgnoreProperties("invoices") 和@JsonIgnoreProperties("year") 添加到实体以避免无限的json recursion。

【讨论】：

当我添加此更新时，我会像这样拨打电话：localhost:8080/appapi/invoices?yearId=1 & 我获得 500 内部服务器错误和无限日志，如下所示：故障安全清理（集合）：org.hibernate .engine.loading.internal.CollectionLoadContext@5f5daaff

【解决方案2】：

我已禁用 Lombok 并且它可以工作

【讨论】：

【解决方案3】：

试着给他一个 Year 对象而不是 id 更好

@CrossOrigin("http://localhost:4200")
public interface InvoiceRepository extends JpaRepository<Invoice, Long> {
    Page<Invoice> findByYear(YearDate year, Pageable page);
}

并在您的服务中获得今年例如，我在服务中创建了一个 getYears 方法：

@Service
public class YearService{

@Autowired
private YearRepository yearRepository;
@Autowired
private InvoiceRepository invoiceRepository;

getYears(idYear:Long){
YearDate yearParam=yearRepository.findById(id).get();
Page<Invoice> invoices=invoiceRepository.findByYear(yearParam,YourPagination)
}

}

【讨论】：