How we implement composite key in table using annotation and xml configuration.

Primary key --    This  is use for the table column to make sure  that  rows will unique.

 

 Composite key --  When  we have   more then two   column  as primary key in the table known

 as composite  key .  

  

 

 

 We  will   consider  an example  with a  table RolesMenuItems . Which   is table for describing the role  of the  employee .   We  have table RolesMenuItems  which has   Role_ID and RolesMenuItem_ID as 

primary key . So  first create  RolesMenu pojo class . Which will have these  primary keys.

 . Now   we  will  discuss how to write   code for the  composite key  for these two  columns.

 

 

CREATE TABLE " RolesMenuItems "

   (

        "Role_ID" VARCHAR2(255 CHAR),

            " MenuItem_ID " VARCHAR2(255 CHAR),

            " EMP_NAME " VARCHAR2(255 CHAR),      PRIMARY KEY(Role_ID, MenuItem_ID)

   );

 

 

First  we  will consider the  xml based configuration .  So  we  have RoleMenu Class  where  we  written  all columns  and getter setter for these column . The RolesMenuItems.hbm.xml  file  for  the pojo class  as  below. 

 

 

RolesMenuItems.hbm.xml

Place the RoleMenu.hbm.xml file under the src/main/resources folder

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-mapping PUBLIC

 "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

 

<hibernate-mapping package="com.bhirkutisoft">

 <class name=" RolesMenuItems " table=" RolesMenuItems ">

   <composite-id>

     <key-property name="RoleId" column="Role_ID" />

     <key-property name=" menuItemID " column=" menuItem_ID " />

 

   </composite-id>

   <property name="empName" column="EMP_NAME" />

 </class>

</hibernate-mapping>

 

 

 

 Here the   primary  key columns are   enclosed in the     <composite-id>

      --------- ----

    </composite-id> 

 

 Now   we  can   see  how  we can code for  it  for  annotation based configuration .  @Embeddable  and      @EmbeddedId two  annotation

 We   use  for   composit  key  column class .

 

 

 

@Embeddable

public class RolesMenu {

    @Column(name = "Role_ID")

    private String roleID;

 

  @Column(name = "MenuItem_ID")

    private String menuItemID;

 

    //getter, setter methods

}

 

 

 

 

 @Entity

 @Table(name = "RolesMenuItems")

 public class RolesMenuItems {

 

     @EmbeddedId

     private RolesMenu roleMenu;

 

      @Column(name = " EMP_NAME ")

      private String empName;

 

 

     

  /*setter getter methods */

 }

 

 

 This   can be    understood  more easily  by another example  of the table Employee .

 

Employee

company_id   VARCHAR(25)

employee_id   VARCHAR(25)

email               VARCHAR(30)

name           VARCHAR(50)

Phone_number  VARCHAR(50)

 

         

 

 

 

 

 

 

 

 

 

 

package com.example.jpa.model;

 

import javax.persistence.Embeddable;

import javax.validation.constraints.NotNull;

import javax.validation.constraints.Size;

import java.io.Serializable;

 

@Embeddable

public class EmployeeIdentity implements Serializable {

    @NotNull

    @Size(max = 20)

    private String employeeId;

 

    @NotNull

    @Size(max = 20)

    private String companyId;

 

    public EmployeeIdentity() {

 

    }

 

    public EmployeeIdentity(String employeeId, String companyId) {

        this.employeeId = employeeId;

        this.companyId = companyId;

    }

 

    public String getEmployeeId() {

        return employeeId;

    }

 

    public void setEmployeeId(String employeeId) {

        this.employeeId = employeeId;

    }

 

    public String getCompanyId() {

        return companyId;

    }

 

    public void setCompanyId(String companyId) {

        this.companyId = companyId;

    }

 

    @Override

    public boolean equals(Object o) {

        if (this == o) return true;

        if (o == null || getClass() != o.getClass()) return false;

 

        EmployeeIdentity that = (EmployeeIdentity) o;

 

        if (!employeeId.equals(that.employeeId)) return false;

        return companyId.equals(that.companyId);

    }

 

    @Override

    public int hashCode() {

        int result = employeeId.hashCode();

        result = 31 * result + companyId.hashCode();

        return result;

    }

}

2. Employee - Domain model

package com.example.jpa.model;

 

import org.hibernate.annotations.NaturalId;

import javax.persistence.Column;

import javax.persistence.EmbeddedId;

import javax.persistence.Entity;

import javax.persistence.Table;

import javax.validation.constraints.NotNull;

import javax.validation.constraints.Email;

import javax.validation.constraints.Size;

 

@Entity

@Table(name = "employees")

public class Employee {

 

    @EmbeddedId

    private EmployeeIdentity employeeIdentity;

 

    @NotNull

    @Size(max = 60)

    private String name;

 

    @NaturalId

    @NotNull

    @Email

    @Size(max = 60)

    private String email;

 

    @Size(max = 15)

    @Column(name = "phone_number", unique = true)

    private String phoneNumber;

 

    public Employee() {

 

    }

 

  public Employee(EmployeeIdentity employeeIdentity, String name, String email, String phoneNumber) {

        this.employeeIdentity = employeeIdentity;

        this.name = name;

        this.email = email;

        this.phoneNumber = phoneNumber;

    }

 

    // Getters and Setters (Omitted for brevity)

}