打印JSON响应中包含类别的子类别列表

Question

我有一张这样的桌子

https://i.stack.imgur.com/ON3JL.png

这是此表的实体类

Where(clause = "active =1")
@Entity
@Table(name = "category", catalog = "businessin")
public class Category implements java.io.Serializable {


    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "id", unique = true, nullable = false)
    private Integer id;
    private String name;
    private Integer parentId;
    private Integer active;
    private String pic;
    @JsonIgnore
    @OneToMany(fetch = FetchType.LAZY, mappedBy = "category")
    private List<Product> products = new ArrayList<Product>();

    setters&getter 
}

我正在使用spring rest和spring数据（jpaRepositories）构建RESTful API，
我希望在将控制器中的主要类别打印为JSON响应时，我希望它们也有一个子类别列表

[
{
id: 1,
name: "Electronics",
parentId: 0,
active: 1,
pic: null
}]

到这个

[
{
id: 1,
name: "Electronics",
parentId: 0,
active: 1,
pic: null
subCategories: [Mobile, Laptops]
}]

Answer 1

这很简单，让你的实体像这样

@Where(clause = "active =1")
@Entity
@Table(name = "category" )
public class Category implements java.io.Serializable {


    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "id", unique = true, nullable = false)
    private Integer id;
    private String name;
    @Column(nullable=false,columnDefinition="int default 1")
    private Integer active;
    private String pic;
    @JsonIgnore
    @OneToMany(fetch = FetchType.LAZY, mappedBy = "category")
    private List<Product> products = new ArrayList<Product>();
    @ManyToOne
       @JoinColumn(name="parent_id")
       @JsonIgnore
   // @ColumnDefault("0")
    private Category parentId;
    @OneToMany(mappedBy="parentId")
    private List<Category> subCategories=new ArrayList<>();

setters and getters

}