Print sub categories list with categories in JSON response - spring

Question

I have mysql table like this
https://i.stack.imgur.com/ON3JL.png
this is entity class for this table
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
}
I'm building RESTful API using spring rest and spring data (jpaRepositories)
I want when printing main categories from controllers as JSON reponse i want them to have also a list of subCategories
example for this
[
{
id: 1,
name: "Electronics",
parentId: 0,
active: 1,
pic: null
}]
to this
[
{
id: 1,
name: "Electronics",
parentId: 0,
active: 1,
pic: null
subCategories: [Mobile, Laptops]
}]

Answer 1

it's simple make your entity like this
#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
}