避免无限循环 Spring 启动

Question

在Spring Boot Rest API 中，我能够使用@JsonIgnore 避免无限循环。在邮递员结果中，相关列表（多边）显示为空。当我将在 Angular 中使用此端点时，即使它在我的邮递员中被 @JsonIgnore 跳过，我是否能够显示该相关列表？

考虑 Matiere 和 PlannificationConcours 之间的关系，其中有一些其他 child，如何避免无限循环和 return null 值。

一侧

@Data
@AllArgsConstructor
@Table(name="Matiere")
public class Matiere extends Audit<String>  implements Serializable {

    @Column(name="ID", nullable=false, length=10)   
    @Id 
    @GeneratedValue(generator="PNU_MATIERE_ID_GENERATOR")   
    @org.hibernate.annotations.GenericGenerator(name="PNU_MATIERE_ID_GENERATOR", strategy="native") 
    private int id;
    
//  @ManyToOne(targetEntity=fdsa.edu.PNUFDSA.Model.Matiere.class, fetch=FetchType.LAZY) 
//  @org.hibernate.annotations.Cascade({org.hibernate.annotations.CascadeType.LOCK})    
//  @JoinColumns(value={ @JoinColumn(name="MatiereID", referencedColumnName="ID", nullable=false) }, foreignKey=@ForeignKey(name="Pre-requis")) 
//  private fdsa.edu.PNUFDSA.Model.Matiere matiere;
    
    @Column(name="Description", nullable=true, length=255)  
    private String description;
    
    @Column(name="Code", nullable=true, length=255) 
    private String code;
    
    @Column(name="Contenu", nullable=true, length=255)  
    private String Contenu;
    
    @Column(name="NombreDeCreditStandard", nullable=false, length=10)   
    private int nombreDeCreditStandard;

    @OneToMany(mappedBy="matiere", targetEntity= Cours.class)
    private List<Cours> cours ;

    @JsonManagedReference
    @OneToMany(mappedBy="matiere", targetEntity= PlannificationConcours.class)
    private List<PlannificationConcours> plannificationConcourses;

    public Matiere() {
    }

多面

@Entity

@AllArgsConstructor

@Table(name="PlannificationConcours")
public class PlannificationConcours  extends Audit<String> implements Serializable {
    public PlannificationConcours() {
    }
    
    @Column(name="ID", nullable=false, length=10)   
    @Id 
    @GeneratedValue(generator="PNU_PLANNIFICATIONCONCOURS_ID_GENERATOR")    
    @org.hibernate.annotations.GenericGenerator(name="PNU_PLANNIFICATIONCONCOURS_ID_GENERATOR", strategy="native")  
    private int id;

    @ManyToOne (targetEntity= Concours.class, fetch=FetchType.LAZY)
    @JoinColumns(value={ @JoinColumn(name="concoursId", referencedColumnName="ID", nullable=true) }, foreignKey=@ForeignKey(name="ConcoursPlanificationConcours"))
    //@JsonBackReference
    private Concours concours;

    @JsonBackReference
    @ManyToOne(targetEntity= Matiere.class, fetch=FetchType.LAZY)
    @JoinColumns(value={ @JoinColumn(name="MatiereId", referencedColumnName="ID", nullable=true) }, foreignKey=@ForeignKey(name="MatierePlanificationConcours"))
    private Matiere matiere;
    
    @Column(name="`Date`", nullable=true)   
    @Temporal(TemporalType.DATE)    
    private java.util.Date Date;
    
    @Column(name="Quotation", nullable=false, length=10)    
    private double quotation;
    
    @Column(name="NoteDePassage", nullable=false, length=10)    
    private double noteDePassage;
    

    @OneToMany(mappedBy="plannificationConcours", cascade = CascadeType.ALL, fetch = FetchType.EAGER, targetEntity= HistoriqueExamenConcours.class)
    private List<HistoriqueExamenConcours> historiqueExamenConcours;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Concours getConcours() {
        return concours;
    }

    public void setConcours(Concours concours) {
        this.concours = concours;
    }
    
    public Matiere getMatiere() {
        return matiere;
    }

    public void setMatiere(Matiere matiere) {
        this.matiere = matiere;
    }

    public java.util.Date getDate() {
        return Date;
    }

    public void setDate(java.util.Date date) {
        Date = date;
    }

    public double getQuotation() {
        return quotation;
    }

    public void setQuotation(double quotation) {
        this.quotation = quotation;
    }

    public double getNoteDePassage() {
        return noteDePassage;
    }

    public void setNoteDePassage(double noteDePassage) {
        this.noteDePassage = noteDePassage;
    }

    public List<HistoriqueExamenConcours> getHistoriqueExamenConcours() {
        return historiqueExamenConcours;
    }

    public void setHistoriqueExamenConcours(List<HistoriqueExamenConcours> historiqueExamenConcours) {
        this.historiqueExamenConcours = historiqueExamenConcours;
    }
}

邮递员回复

    "id": 2,
    "description": "Prgrammation C#",
    "code": "C Sharp",
    "nombreDeCreditStandard": 2,
    "cours": [],
    "contenu": "C#",
    "plannificationConcours": null
}```

Answer 1

你必须先明白你的Frontend(Angular)和Backend(Spring Boot)是2个独立的应用程序。

I was able to avoid infinite loop with @JsonIgnore. In the postman result, the related list (many side) show null.

因此，您已通过修改返回对象转换为 JSON 对象的方式来修改后端，使其不进入无限循环。如果您的后端在转换为 JSON 对象时会陷入无限循环，现在将在此时写入一个空值以避免无限循环。

When i will use this endpoint in Angular, will i be able to display that related list even if it is skipped by @JsonIgnore in my postman

您的 angular 应用程序将收到您的邮递员收到的确切信息，即来自您后端的答复。所以答案是否定的。

避免无限循环 Spring 启动

Avoiding Infinite Loop Spring Boot

angular

spring

spring-boot

rest

spring-data