无法写内容：无限递归

Question

实体关系图：

我想收到翻译，但even2会链接回翻译。 所以它会崩溃，因为它不断循环..

翻译实体：

element

元素实体：

package com.exstodigital.photofactory.model;

import javax.persistence.*;

import java.io.Serializable;

/**
 * Created by youri on 21-09-16.
 */
@Table(name = "translation")
@Entity
public class Translation implements Serializable {
    @Id
    @GeneratedValue
    private int id;

    public int getId() {
        return id;
    }

    private String text;

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    @OneToOne
    @JoinColumn(name = "language_id")
    private Language language;

    public Language getLanguage() {
        return language;
    }

    @OneToOne
    @JoinColumn(name = "element_id")
    private Element element;

    public Element getElement() {
        return element;
    }

    public Translation(int id, String text) {
        this.id = id;
        this.text = text;
    }

    public Translation() {
        // Empty constructor
    }

    @Override
    public boolean equals(Object obj) {
        return obj instanceof Translation && (!this.text.equals(((Translation) obj).text));
    }
}

TranslationDaoImpl：

package com.exstodigital.photofactory.model;

import javax.persistence.*;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * Created by youri on 21-09-16.
 */
@Entity
@Table(name = "element")
public class Element implements Serializable {
    @Id
    @GeneratedValue
    private int id;

    public int getId() {
        return id;
    }

    private String label;

    public String getLabel() {
        return label;
    }

    public void setLabel(String label) {
        this.label = label;
    }

    @OneToMany
    @JoinColumn(name = "element_id")
    private List<Translation> translations = new ArrayList<>();

    public List<Translation> getTranslations() {
        return Collections.unmodifiableList(translations);
    }

    public Element(int id, String label) {
        this.id = id;
        this.label = label;
    }

    public Element() {
        // Empty constructor
    }

    @Override
    public boolean equals(Object obj) {
        return obj instanceof Element && (this.id != ((Element) obj).id || !this.label.equals(((Element) obj).label));
    }
}

Answer 1

你已经建立了错误的关系，从一方面你给OneToOne和同一个但是从第二个实体你给OneToMany

您的代码：

@Table(name = "translation")
@Entity
public class Translation implements Serializable {

    @OneToOne
    @JoinColumn(name = "element_id")
    private Element element;

}

@Entity
@Table(name = "element")
public class Element implements Serializable {

    @OneToMany
    @JoinColumn(name = "element_id")
    private List<Translation> translations = new ArrayList<>();
}

OneToOne的正确代码：

@Table(name = "translation")
@Entity
public class Translation implements Serializable {

    @JsonIgnore    
    @OneToOne
    @JoinColumn(name = "element_id")
    private Element element;

}

@Entity
@Table(name = "element")
public class Element implements Serializable {

    @OneToOne
    (mappedBy="element")
    private Translation translation;
}

OneToMany的正确代码：

@Table(name = "translation")
@Entity
public class Translation implements Serializable {

    @JsonIgnore
    @ManyToOne
    @JoinColumn(name = "element_id")
    private Element element;

}

@Entity
@Table(name = "element")
public class Element implements Serializable {

    @OneToMany
    (mappedBy="element")
    private List<Translation> translations;
}

  

使用“@JsonIgnore”来避免进入你的无限递归   代码