Spring Boot Rest 服务 Angular

Question

I have an application in front end i use angular and back end i use Spring boot. In my front end i must upload a CSV file that insert data in tables. So i send data to the backend which save it. My problem: i have a class Individus with relation @OneToMany to others class like as comptes. So when i try to get All individus with this Rest service : http://localhost:8080/api/individus , i have a parsing json data error.

at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.9.6.jar:2.9.6]
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145) ~[jackson-databind-2.9.6.jar:2.9.6]
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107) ~[jackson-databind-2.9.6.jar:2.9.6]
at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25) ~[jackson-databind-2.9.6.jar:2.9.6]
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727) ~[jackson-databind-2.9.6.jar:2.9.6]

Here is my class Individus:

@Entity 

public class Individu implements Serializable {

@Id
private String nui;
private int civility; 
private String lastName;
private String useName;
private String firstName;
@Temporal(TemporalType.DATE)
@JsonFormat(pattern="dd/MM/yyyy")
private Date birthDate;
private String birthPlace;
private String birthCountry;
private String birthCountryLib;
private String nationality;
@OneToMany(mappedBy="individu", fetch = FetchType.LAZY)
private Collection<Compte> comptes;
@OneToMany(mappedBy="individu", fetch = FetchType.LAZY)
private Collection<Adresse> adresses;
@OneToMany(mappedBy="individu", fetch = FetchType.LAZY)
private Collection<Contact> contacts;
@OneToMany(mappedBy="individu", fetch = FetchType.LAZY)
private Collection<Iban> ibans;ode here

Is some one have a solution for me?

Answer 1

You didn't provide enough of the stacktrace to show what the actual error is, but I suspect that you're running into a problem with a circular graph, as the objects in your Individu class' collections (eg Compte, Ardresse) probably hold a reference to the parent Individu instance.

The solution in that case is to add a @JsonIgnore annotation to the children's references to the parent. This is most likely an attribute in the child that is currently marked with an @ManyToOne annotation.

Answer 2

this is another solution

public class Produit{.....
@ManyToOne(optional=false,fetch=FetchType.LAZY)
@JsonBackReference
private Category category;....}


public class Category{....
@OneToMany(fetch=FetchType.LAZY,mappedBy="category")
@JsonManagedReference
private Collection<Produit> produits;....}