I know this is a frequently asked question, but I couldn't find any answers because I have 3 classes and I generally have problems to build the given structure:

type OrderItem = {
    count: number,
    price: number,
    order: number,
    subItems: {
        count: number,
        name: string,
        price: number,
        extraItems: {
            count: number,
            name: string,
            price: number,
        }
    }
};

This is my try at doing it in Java with JPA:

Order.java

package de.gabriel.mcdonaldsproject.models;

import javax.persistence.*;
import java.io.Serializable;
import java.util.List;


@Entity
@Table(name = "orders", schema = "public")
public class Order implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "order_generator")
    @SequenceGenerator(name = "order_generator", sequenceName = "order_seq")
    private long id;
    private List<Item> products; // <--------- 'Basic' attribute type should not be a container

    public Order() {
    }

    public Order(List<Item> products) {
        this.products = products;
    }

    public long getId() {
        return id;
    }

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

    public List<Item> getProducts() {
        return products;
    }

    public void setProducts(List<Item> product) {
        this.products = product;
    }
}

Item.java

package de.gabriel.mcdonaldsproject.models;

import javax.persistence.*;
public class Item{

    private double count;
    private double price;
    private double order;
    private SubItems subItems;

    public Item(){}
    public Item(double count, double price, double order, SubItems subItems) {
        this.count = count;
        this.price = price;
        this.order = order;
        this.subItems = subItems;
    }

    public double getCount() {
        return count;
    }

    public void setCount(double count) {
        this.count = count;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public double getOrder() {
        return order;
    }

    public void setOrder(double order) {
        this.order = order;
    }

    public SubItems getSubItems() {
        return subItems;
    }

    public void setSubItems(SubItems subItems) {
        this.subItems = subItems;
    }
}

SubItems.java

package de.gabriel.mcdonaldsproject.models;

import javax.persistence.*;
import java.util.List;
public class SubItems {
    private double count;
    private String name;
    private double price;
    private List<String> extraItems;

    public SubItems(){}

    public SubItems(double count, String name, double price, List<String> extraItems) {
        this.count = count;
        this.name = name;
        this.price = price;
        this.extraItems = extraItems;
    }

    public double getCount() {
        return count;
    }

    public void setCount(double count) {
        this.count = count;
    }

    public String getName() {
        return name;
    }

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

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public List<String> getExtraItems() {
        return extraItems;
    }

    public void setExtraItems(List<String> extraItems) {
        this.extraItems = extraItems;
    }
}

Does someone have an idea on how to rebuild this structure in Java with JPA so it also gets saved in the database?

CodePudding user response：

If this object orderitem is not going to expand, I would suggest JSON string saving in the database.

OR you can do following mappings:

@OneToMany(mappedBy="order")
public Order(List<Item> products) {
    this.products = products;
}


@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "subitem_id", referencedColumnName = "id")
private SubItems subItems;

CodePudding user response：

Update the following information like this :

@Embeddable
public class Item {
   // .....
   @Embedded
   private SubItems subItems;
   //.......
}

@Embeddable
public class SubItems {
   // .....
   @ElementCollection
   private List<String> extraItems;
   //.......
}


@Entity
@Table(name = "orders", schema = "public")
public class Order implements Serializable {
   //.....
   @ElementCollection
   private List<Item> products;
   //.......
}