ManyToOne, oneToMany with join table - mysql

Question

I have this example, witch it works, I just want to modify it but I can't do it.
Here is the link of the example :example link
Anyway I posting it here to:
Here is the picture of entitys :
Entity-Relation
CREATE TABLE `stock` (
`STOCK_ID` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
`STOCK_CODE` VARCHAR(10) NOT NULL,
`STOCK_NAME` VARCHAR(20) NOT NULL,
PRIMARY KEY (`STOCK_ID`) USING BTREE,
UNIQUE KEY `UNI_STOCK_NAME` (`STOCK_NAME`),
UNIQUE KEY `UNI_STOCK_ID` (`STOCK_CODE`) USING BTREE
)
CREATE TABLE `category` (
`CATEGORY_ID` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
`NAME` VARCHAR(10) NOT NULL,
`DESC` VARCHAR(255) NOT NULL,
PRIMARY KEY (`CATEGORY_ID`) USING BTREE
)
CREATE TABLE `stock_category` (
`STOCK_ID` INT(10) UNSIGNED NOT NULL,
`CATEGORY_ID` INT(10) UNSIGNED NOT NULL,
`CREATED_DATE` DATE NOT NULL,
`CREATED_BY` VARCHAR(10) NOT NULL,
PRIMARY KEY (`STOCK_ID`,`CATEGORY_ID`),
CONSTRAINT `FK_CATEGORY_ID` FOREIGN KEY (`CATEGORY_ID`)
REFERENCES `category` (`CATEGORY_ID`),
CONSTRAINT `FK_STOCK_ID` FOREIGN KEY (`STOCK_ID`)
REFERENCES `stock` (`STOCK_ID`)
)
And here are the java classes:
Stock.java
package com.mkyong.stock;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import static javax.persistence.GenerationType.IDENTITY;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;
#Entity
#Table(name = "stock", catalog = "mkyongdb", uniqueConstraints = {
#UniqueConstraint(columnNames = "STOCK_NAME"),
#UniqueConstraint(columnNames = "STOCK_CODE") })
public class Stock implements java.io.Serializable {
private Integer stockId;
private String stockCode;
private String stockName;
private Set<StockCategory> stockCategories = new HashSet<StockCategory>(0);
public Stock() {
}
public Stock(String stockCode, String stockName) {
this.stockCode = stockCode;
this.stockName = stockName;
}
public Stock(String stockCode, String stockName,
Set<StockCategory> stockCategories) {
this.stockCode = stockCode;
this.stockName = stockName;
this.stockCategories = stockCategories;
}
#Id
#GeneratedValue(strategy = IDENTITY)
#Column(name = "STOCK_ID", unique = true, nullable = false)
public Integer getStockId() {
return this.stockId;
}
public void setStockId(Integer stockId) {
this.stockId = stockId;
}
#Column(name = "STOCK_CODE", unique = true, nullable = false, length = 10)
public String getStockCode() {
return this.stockCode;
}
public void setStockCode(String stockCode) {
this.stockCode = stockCode;
}
#Column(name = "STOCK_NAME", unique = true, nullable = false, length = 20)
public String getStockName() {
return this.stockName;
}
public void setStockName(String stockName) {
this.stockName = stockName;
}
#OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.stock", cascade=CascadeType.ALL)
public Set<StockCategory> getStockCategories() {
return this.stockCategories;
}
public void setStockCategories(Set<StockCategory> stockCategories) {
this.stockCategories = stockCategories;
}
}
StockCategory.java
package com.mkyong.stock;
import java.util.Date;
import javax.persistence.AssociationOverride;
import javax.persistence.AssociationOverrides;
import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.JoinColumn;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.Transient;
#Entity
#Table(name = "stock_category", catalog = "mkyongdb")
#AssociationOverrides({
#AssociationOverride(name = "pk.stock",
joinColumns = #JoinColumn(name = "STOCK_ID")),
#AssociationOverride(name = "pk.category",
joinColumns = #JoinColumn(name = "CATEGORY_ID")) })
public class StockCategory implements java.io.Serializable {
private StockCategoryId pk = new StockCategoryId();
private Date createdDate;
private String createdBy;
public StockCategory() {
}
#EmbeddedId
public StockCategoryId getPk() {
return pk;
}
public void setPk(StockCategoryId pk) {
this.pk = pk;
}
#Transient
public Stock getStock() {
return getPk().getStock();
}
public void setStock(Stock stock) {
getPk().setStock(stock);
}
#Transient
public Category getCategory() {
return getPk().getCategory();
}
public void setCategory(Category category) {
getPk().setCategory(category);
}
#Temporal(TemporalType.DATE)
#Column(name = "CREATED_DATE", nullable = false, length = 10)
public Date getCreatedDate() {
return this.createdDate;
}
public void setCreatedDate(Date createdDate) {
this.createdDate = createdDate;
}
#Column(name = "CREATED_BY", nullable = false, length = 10)
public String getCreatedBy() {
return this.createdBy;
}
public void setCreatedBy(String createdBy) {
this.createdBy = createdBy;
}
public boolean equals(Object o) {
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
StockCategory that = (StockCategory) o;
if (getPk() != null ? !getPk().equals(that.getPk())
: that.getPk() != null)
return false;
return true;
}
public int hashCode() {
return (getPk() != null ? getPk().hashCode() : 0);
}
}
Stockcategoryid.java
package com.mkyong.stock;
import javax.persistence.Embeddable;
import javax.persistence.ManyToOne;
#Embeddable
public class StockCategoryId implements java.io.Serializable {
private Stock stock;
private Category category;
#ManyToOne
public Stock getStock() {
return stock;
}
public void setStock(Stock stock) {
this.stock = stock;
}
#ManyToOne
public Category getCategory() {
return category;
}
public void setCategory(Category category) {
this.category = category;
}
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
StockCategoryId that = (StockCategoryId) o;
if (stock != null ? !stock.equals(that.stock) : that.stock != null) return false;
if (category != null ? !category.equals(that.category) : that.category != null)
return false;
return true;
}
public int hashCode() {
int result;
result = (stock != null ? stock.hashCode() : 0);
result = 31 * result + (category != null ? category.hashCode() : 0);
return result;
}
}
Category.java
package com.mkyong.stock;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import static javax.persistence.GenerationType.IDENTITY;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
#Entity
#Table(name = "category", catalog = "mkyongdb")
public class Category implements java.io.Serializable {
private Integer categoryId;
private String name;
private String desc;
private Set<StockCategory> stockCategories = new HashSet<StockCategory>(0);
public Category() {
}
public Category(String name, String desc) {
this.name = name;
this.desc = desc;
}
public Category(String name, String desc, Set<StockCategory> stockCategories) {
this.name = name;
this.desc = desc;
this.stockCategories = stockCategories;
}
#Id
#GeneratedValue(strategy = IDENTITY)
#Column(name = "CATEGORY_ID", unique = true, nullable = false)
public Integer getCategoryId() {
return this.categoryId;
}
public void setCategoryId(Integer categoryId) {
this.categoryId = categoryId;
}
#Column(name = "NAME", nullable = false, length = 10)
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
#Column(name = "[DESC]", nullable = false)
public String getDesc() {
return this.desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
#OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.category")
public Set<StockCategory> getStockCategories() {
return this.stockCategories;
}
public void setStockCategories(Set<StockCategory> stockCategories) {
this.stockCategories = stockCategories;
}
}
Now I want for a stock to have only one Category, so basicaly I have to change from #OneToMany In Stock.java to ManyToOne but if I only changed to that it gives me error.
Can someone help me, please .
It should be something like :
#ManyToOne(fetch = FetchType.LAZY, mappedBy = "pk.stock", cascade=CascadeType.ALL)
private StockCategory stockgatery;
//setter and getter methods
//or something like
#ManyToOne
#JoinColumn(name="pk.stock"
But I can't figure it out.

Answer 1

Try something like this below ...
#ManyToOne #JoinColumns({ #JoinColumn(name = "STOCK_ID", referencedColumnName = "STOCK_ID"),
#JoinColumn(name = "CATEGORY_ID", referencedColumnName = "CATEGORY_ID") })
private StockCategory stockCategory;