Question

我有一个实体，其中一个字段具有一对多关系。

看起来像这样。

@Entity
@Table(name = "company")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class Company implements Serializable {

    private static final long serialVersionUID = 1L;

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

    @NotNull
    @Column(name = "name", nullable = false)
    private String name;

    @NotNull
    @Column(name = "short_name", nullable = false)
    private String shortName;

    @NotNull
    @Column(name = "customer_number", nullable = false)
    private String customerNumber;

    @OneToMany(mappedBy = “company”)
    @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
    private Set<BusinessType> businessTypes = new HashSet<>();

    … getters setters


}

@Entity
@Table(name = “business_type")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class BusinessType implements Serializable {

    private static final long serialVersionUID = 1L;

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

    @NotNull
    @Enumerated(EnumType.STRING)
    @Column(name = "type", nullable = false)
    private BType type;

    @ManyToOne(optional = false)
    @NotNull
    @JsonIgnore
    private Company company;

    … getters setters
}

public enum BType {
    TYPE1, TYPE2, TYPE3
}

数据库表如下：

公司（编号，名称，简称，客户编号）

business_type（ID，类型，company_id）

当我请求特定的REST路径时，我得到以下JSON结构：

{
  "id" : 1,
  "name" : “Business name”,
  "shortName" : "Business short name",
  "customerNumber" : "1234",
  “businessTypes" : null
}

但是我期望以下内容：

{
  "id" : 1,
  "name" : “Business name”,
  "shortName" : "Business short name",
  "customerNumber" : "1234",
  "businessTypes" : [{
    "id" : 1,
    “type” : “TYPE1”
  }]
}

当值在数据库中时为什么businessTypes null？

我想念什么？

Answer 1

尝试在@JoinColumn(name="company_id")之后添加@ManyToOne

Answer 2

@OneToMany(mappedBy = "company", fetch = FetchType.EAGER)

默认为LAZY，除非明确请求，否则不加载关系实体

Spring Boot Hibernate OneToMany Null JoinColumn

2 个答案: