hibernate one to many reationship.

[Jigar Naik]

Hi,

I have two database table Customer and Product which share one to many relationship. Now from the front end i am getting customer object and setting it into session. then i 2 product detials for the same customer and i set it into customer object.

So basically i will BE having List<Product> which will be of size 2.

Now when i insert customer object into database using hibernate. the primary key of the customer should get inserted into product table. which is not getting inserted.

So is there any michenism through which when my customer object gets inserted into database and database autogenerated customer's primary key gets inserted into Product table. ???

Or i have to explicitly manage ?

Bellow is my Customer.java

    
package com.india.customer;

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

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import com.india.product.Product;

@Entity
@Table(name = "customer", schema = "customer_manager")
public class Customer implements Serializable {

	public Customer() {

	}

	private Long id;
	private String customerName;
	private String email;
	private List<Product> products = new ArrayList<Product>();

	@Id
	@GeneratedValue
	public Long getId() {
		return id;
	}

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

	@Column(name = "customer_name", length = 50)
	public String getCustomerName() {
		return customerName;
	}

	public void setCustomerName(String customerName) {
		this.customerName = customerName;
	}

	@Column(name = "customer_email", length = 60)
	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	@OneToMany(mappedBy = "customer", targetEntity = Product.class, fetch = FetchType.EAGER, cascade = CascadeType.ALL)
	public List<Product> getProducts() {
		return products;
	}

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

and bellow is my Product.java

package com.india.product;

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

import com.india.customer.Customer;

@Entity
@Table(name = "product", schema = "customer_manager")
public class Product implements Serializable {

	public Product() {

	}

	private Long id;
	private String productCode;
	private String productName;
	private Customer customer;

	@Id
	@GeneratedValue
	public Long getId() {
		return id;
	}

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

	@Column(name = "product_code", length = 20)
	public String getProductCode() {
		return productCode;
	}

	public void setProductCode(String productCode) {
		this.productCode = productCode;
	}

	@Column(name = "product_name", length = 60)
	public String getProductName() {
		return productName;
	}

	public void setProductName(String productName) {
		this.productName = productName;
	}

	@ManyToOne
	@JoinColumn(name = "customer_id")
	public Customer getCustomer() {
		return customer;
	}

	public void setCustomer(Customer customer) {
		this.customer = customer;
	}

}

and bellow is my main method.

package com.india.test;

import java.util.ArrayList;
import java.util.List;

import org.hibernate.HibernateException;
import org.hibernate.Session;

import com.india.customer.Customer;
import com.india.hbmutil.HibernateUtil;
import com.india.product.Product;

public class Test {

	private static Customer prepareCustomer() {
		
		Product im = new Product();
		im.setProductCode("IM");
		im.setProductName("Interaction Manager");
		
		Product cm = new Product();
		cm.setProductCode("CM");
		cm.setProductName("Campaign Manager");
		
		Product rm = new Product();
		rm.setProductCode("RM");
		rm.setProductName("Response Manager");
		
		List<Product> products = new ArrayList<Product>();
		products.add(im);
		products.add(cm);
		products.add(rm);
		
		Customer customer = new Customer();
		customer.setCustomerName("Jigar Naik");
		customer.setEmail("[e-mail]");
		customer.setProducts(products);
		
		return customer;
		
	}
	public static void main(String[] args) {
		try {
			Session session = HibernateUtil.beginTransaction();
			session.save(prepareCustomer());
			HibernateUtil.commitTransaction();
		} catch (HibernateException e) {
			e.printStackTrace();
			HibernateUtil.rollbackTransaction();
		}
	}
}

In my Product table the customer_id is going null for all the product.

[Cameron Wallace McKenzie]

What happens when you save both sides of the relationship? Save the products and then save the Customer. You might have some more success. Here's a little example, perhaps even simlpler than your scenario, that successfully saves both sides of a one-to-many hibernate relationship:

Saving Both Sides of a One-To-Many Relationship with Hibernate and JPA

The pertinent code in the example is as follows. Notice that both sides of the relationship are being saved:

 
Session session = HibernateUtil.beginTransaction();
Team team = new Team();
Player p1 = new Player();
Player p2 = new Player();
session.save(team);
session.save(p1);
session.save(p2);
team.setName("Pickering Atoms");
p1.setNickName("Lefty");
p1.setTeam(team);
p2.setNickName("Blinky");
p2.setTeam(team);
HibernateUtil.commitTransaction();   

-Cameron McKenzie

[Jigar Naik]

Hi Cameron

Yes, that is right.

but i have four POJO (Customer, Product, License & Transaction) which have relationship with each other, each POJO contains 10 to 15 fields. and i have a single JSP page from which i am getting all the information in one request or multiple Ajax request(in case of one to many relationship). So basically i have integrated struts 2 and hibernate, so all of my form fields are automatically geting set in 4 pojo.

and in the case where i have one to many relationshio between i.e. in customer to products. i am making ajax call and saves all the product in HttpSession object. and finally on submit of JSP page i wanted to put all the POJOs to database.

And the way suggested by you, i have to do lot of getXXX and setXXX operations which is tedious as each pojo contains lots of fields.

Do i have any alternative ?

[Cameron Wallace McKenzie]

I'm wondering if you might be able to configure the 'cascade-type' in the XML to address this. I'll dig...

-Cameron McKenzie

[Jigar Naik]

package com.test;

import java.util.ArrayList;
import java.util.List;

import org.hibernate.Session;

import com.customer.Customer;
import com.hbmutil.HibernateUtil;
import com.product.Product;

public class Test {

	public static void main(String[] args) {
		
		Customer customer = new Customer();
		customer.setCustomerName("Jigar Naik");
		customer.setCustomerEmail("[e-mail]");
		
		Product im = new Product();
		im.setProductCode("IM");
		im.setProductName("Interaction Manager");
		im.setCustomer(customer);
		
		
		Product rm = new Product();
		rm.setProductCode("RM");
		rm.setProductName("Response Manager");
		rm.setCustomer(customer);
		
		List<Product> products = new ArrayList<Product>();
		products.add(im);
		products.add(rm);
		
		customer.setProducts(products);
		
		try{
			Session session = HibernateUtil.beginTransaction();
			session.save(customer);
			HibernateUtil.commitTransaction();
		}catch(Exception e){
			e.printStackTrace();
			HibernateUtil.rollbackTransaction();
		}
	}
}

output

Table : Product 
ID	PRODUCT_CODE	PRODUCT_NAME		CUSTOMER_ID
---------------------------------------------------------------
5	IM		Interaction Manager	4
6	RM		Response Manager	4