スプリングデータエンティティ：再帰を停止

Question

私はCrudRepositoryに2つのエンティティを持っています。

機械エンティティ

_machine_id || name || description 

特性実体

characteristic_id || machine_id || name || description || type || value 

JSON：

[{"name":"CNC","description":"Metallverarbeitung","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics":[{"name":"Final Piping Connections","description":"Final Piping Connections","type":0,"value":0,"machine":{"name":"Marvins Maschine","description":"Bizeps","characteristics": 

質問：なぜ再帰があるとどのように私はそれを生成することを防ぐことができますか？

マシン

@Entity 
public class Machine { 
    private int machine_id; 

    private String name; 

    private String description; 

    private Set<Characteristic> characteristics; 

    @OneToMany(fetch = FetchType.EAGER, mappedBy = "machine", cascade = CascadeType.ALL) 
    public Set<Characteristic> getCharacteristics() { 
     return characteristics; 
    } 

    public void setCharacteristics(Set<Characteristic> characteristics){ 
     this.characteristics = characteristics; 
    } 

    public Machine(){} 

    public Machine(String name, String description){ 
     this.name = name; 
     this.description = description; 
    } 

    @Override 
    public String toString() { 
     return "Machine [id=" + machine_id + ", name=" + name + ", description=" + description + "]"; 
    } 

    @Id 
    @GeneratedValue 
    public int getId() { 
     return machine_id; 
    } 

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

    @Column 
    public String getName() { 
     return name; 
    } 

    public void setName(String name) { 
     this.name = name; 
    } 

    @Column 
    public String getDescription() { 
     return description; 
    } 

    public void setDescription(String description) { 
     this.description = description; 
    } 
} 

特性

@Entity 
public class Characteristic { 
    private int characteristic_id; 

    private String name; 

    private String description; 

    private int type; 

    private int value; 

    private Machine machine; 

    @ManyToOne 
    @JoinColumn(name="machine_id") 
    public Machine getMachine(){ 
     return machine; 
    } 

    public void setMachine(Machine machine){ 
     this.machine = machine; 
    } 

    public Characteristic() {} 

    @Id 
    @GeneratedValue 
    public int getId() { 
     return characteristic_id; 
    } 

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

    @Column 
    public String getName() { 
     return name; 
    } 

    public void setName(String name) { 
     this.name = name; 
    } 

    @Column 
    public String getDescription() { 
     return description; 
    } 

    public void setDescription(String description) { 
     this.description = description; 
    } 

    @Column 
    public int getType() { 
     return type; 
    } 

    public void setType(int type) { 
     this.type = type; 
    } 

    @Column 
    public int getValue() { 
     return value; 
    } 

    public void setValue(int value) { 
     this.value = value; 
    } 

    @Override 
    public String toString() { 
     return "Characteristic [id=" + characteristic_id + ", name=" + name + ", description=" + description + ", type=" + type 
       + ", value=" + value + "]"; 
    } 
} 

Answer 1

参加要素の1つに@JsonIgnore注釈を追加します。

要素は互いに参照します。そして、json-parserはオブジェクトのすべてのメンバーをjsonifiyしようとします。したがって、手動で停止しなければ再帰的です。

こちらもご覧ください：Infinite Recursion with Jackson JSON and Hibernate JPA issue