"Welcome To Ashok IT"				
			                  "Spring Boot and MicroServices"
                                          Topic : Spring Data JPA - Paging And Sorting
                                           Date : 17/10/2024
                                             (Session - 29)
_____________________________________________________________________________________________________________________________
PagingAndSortingRepoistory Interface
====================================
* It is child Interface of Repoistory Interface.

* This interface contains two abstract methods related to pagination & sorting.

Pagination
==========
* The Process of displaying bulk of records from Database as page by page is called Pagination.

* Each page will contains specific no of records.

* As business owner he/she will fixing about no of records to be display per page.

* In Spring data JPA Pagination can be achieved through "Pageable" Object.

* Inorder to get the Pageable object we need to use the below Statement

       Pageable pg = PageRequest.of(PageNo,PageSize);

       PageNo Index always Start from "0" Index.

       PageSize will provide input based on business requirement(5,10,15,20 etc.,)

*********************
Example on Pagination            
*********************
    1000 Records are available In Database Table

    Dividing the Records into Pages and Each Page will contains 100 Records 

    Total No Of Pages  = No Of Records in Database Table / Page per Count 
        
    Total No Of Pages  =  1000 / 100 

    Total No Of Pages  =  10 (0 - 9)

    Pageable pg  = PageRequest.of(0,100); //1-100 Records 
    Pageable pg1 = PageRequest.of(3,100); //400-500 Records


Sorting
=======
* When we are retriveing records of DB Table either ascending order (or) descending order based on some property.
              
* Sorting will takes place in the following order 

    1) Special Characters(?,+,',' etc)

    2) Numbers
               
    3) UpperCase Alphabets

    4) LowerCase Alphabets

* In Spring Data JPA Sorting will be achieved through Sort Object.


Hierarchy
=========
                     Repoistory(I)       >>>>> Parent Interface (Marker Interface)
                       ^
                       |
                       
                   CrudRepoistory(I)   >>>>>> Child Interface(12 Abstract Methods)
                        ^
                        |



                 Repoistory(I)       >>>>> Parent Interface (Marker Interface)
                       ^
                       |                       
                 PagingAndSortingRepoistory(I) >>>>> Child Interface(2 Abstract Methods)
                   
                        |-> Iterable<T> findAll(Sort Object);  >>> This method supports for Sorting Entities based on some                                                                         Property.
                        |-> Page<T> findAll(Pageable pageable) >>> This Method supports for getting Entities based on                                                                              Pageable Object


Example Application
===================

Customer.java
=============
package com.ashokit.enities;

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.Id;
import jakarta.persistence.Table;

@Entity
@Table(name = "ashokit_customers")
public class Customer {
	
	@Id
	@GeneratedValue  //Auto Strategy
	@Column(name="customer_id")
	private Integer customerId;
	
	@Column(name="customer_name")
	private String customerName;
	
	@Column(name="customer_location")
	private String customerLocation;
	
	public Customer() {
		
	}
	
	public Customer(Integer customerId, String customerName, String customerLocation) {
		this.customerId = customerId;
		this.customerName = customerName;
		this.customerLocation = customerLocation;
	}
	
	public Customer(String customerName, String customerLocation) {
		this.customerName = customerName;
		this.customerLocation = customerLocation;
	}

	public void setCustomerId(Integer customerId) {
		this.customerId = customerId;
	}
	
	public Integer getCustomerId() {
		return customerId;
	}
	
	public void setCustomerName(String customerName) {
		this.customerName = customerName;
	}
	
	public String getCustomerName() {
		return customerName;
	}
	
	public void setCustomerLocation(String customerLocation) {
		this.customerLocation = customerLocation;
	}
	
	public String getCustomerLocation() {
		return customerLocation;
	}

	@Override
	public String toString() {
		return "Customer [customerId=" + cutomerId + ", customerName=" + customerName + ", customerLocation="
				+ customerLocation + "]";
	}
}


CustomerDao.java
================
package com.ashokit.dao;

import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.PagingAndSortingRepository;

import com.ashokit.enities.Customer;

public interface CustomerDao extends PagingAndSortingRepository<Customer, Integer>,CrudRepository<Customer, Integer>{

}

CustomerService.java
====================
package com.ashokit.services;

import java.util.List;

import com.ashokit.enities.Customer;

public interface CustomerService {
	
	//Method for Fetching records based on supplied PageNo
	public List<Customer> getCustomerInfo(int pageNo, int pageSize);
	
	//Method for Fetching all the page of Records
	public void getCustomerInfo();

	//Method for saving customers information for dummy data
	public Iterable<Customer> saveAllCustomers(List<Customer> customers);
}

CustomerServiceImpl.java
========================
package com.ashokit.services;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Sort;
import org.springframework.data.domain.Sort.Direction;
import org.springframework.stereotype.Service;

import com.ashokit.dao.CustomerDao;
import com.ashokit.enities.Customer;

@Service
public class CustomerServiceImpl implements CustomerService{

	//Injecting the DAO Object
	@Autowired
	private CustomerDao customerDao;
	
	@Override
	public List<Customer> getCustomerInfo(int pageNo, int pageSize) {
		//Creating PageRequest For Pulling customer based on pageNo & pageSize
		PageRequest pageableCustomer = PageRequest.of(pageNo, pageSize);
		
		//Passing the PageRequest object to findAll
		Page<Customer> pageCustomers = customerDao.findAll(pageableCustomer);
		
		//getting the Content of an Page......
		List<Customer> customersList =pageCustomers.getContent();
		
		return customersList;
	}
	
	@Override
	public void getCustomerInfo() {
		//Wanted to display all the pages of information
		int pageSize = 5;
		
		//Getting the customers count from Database Table
		long customerCount = customerDao.count();
		
		//Find the page count 
		// 15/5 = 3, 15/4 = 4 (modify pagecount) 
		long pageCount  = customerCount/pageSize; // 16/5 = 4
		
		//Modifying the pageCount
		pageCount  = (customerCount % pageSize == 0)? pageCount : ++pageCount;
		
		//displaying the Records page by page
		for(int pageNo = 0 ; pageNo < pageCount; pageNo++) {
			
			//Preparing the PageRequest Object
			//PageRequest pageCustomers = PageRequest.of(pageNo, pageSize);
			//PageRequest pageCustomers = PageRequest.of(pageNo, pageSize,Sort.by("customerName"));
			PageRequest pageCustomers = PageRequest.of(pageNo, pageSize,Sort.by(Direction.DESC, "customerName"));
			
			//Passing PageRequest object to findAll()
			Page<Customer> customersPage = customerDao.findAll(pageCustomers);
			
			//getting the content from Page
			System.out.println("Page No :: "+(pageNo+1)+ " Records........");
			customersPage.getContent().forEach(System.out::println);
		}
	}
	
	@Override
	public Iterable<Customer> saveAllCustomers(List<Customer> customers) {
		
		 Iterable<Customer> savedCustomers = customerDao.saveAll(customers);
		 
		 return savedCustomers;
	}
}

application.properties
======================
#configuring the Database properties
spring.datasource.driver-class-name=oracle.jdbc.OracleDriver
spring.datasource.url=jdbc:oracle:thin:@localhost:1521:xe
spring.datasource.username=system
spring.datasource.password=manager

#Hibernate Configuration
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true

Application.java
===============
package com.ashokit;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import com.ashokit.enities.Customer;
import com.ashokit.services.CustomerService;

@SpringBootApplication
public class Application implements CommandLineRunner {
	
	@Autowired
	private CustomerService customerService;

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}
	
	@Override
	public void run(String... args) throws Exception {
		
		//saveAll the Customers Information
		//customerService.saveAllCustomers(getCustomersData());
		
		//PageSize=5, PageNo=0, TotalRecords=15, No of Pages=3(0 to 2), 
		//List<Customer> customers = customerService.getCustomerInfo(3, 5);
		
		//Displaying the page of customers information
		//customers.forEach(eachCustomer -> System.out.println(eachCustomer));
		
		customerService.getCustomerInfo();
	}
	
	
	public List<Customer> getCustomersData(){
		
		Customer customer1 = new Customer("Mahesh","Hyderabad1");
		Customer customer2 = new Customer("Suresh","Hyderabad2");
		Customer customer3 = new Customer("Rajesh","Hyderabad3");
		Customer customer4 = new Customer("Ramesh","Hyderabad4");
		Customer customer5 = new Customer("Nagesh","Hyderabad5");
		Customer customer6 = new Customer("Yagnesh","Hyderabad6");
		Customer customer7 = new Customer("Ganesh","Hyderabad7");
		Customer customer8 = new Customer("Naresh","Hyderabad8");
		Customer customer9 = new Customer("Rameshwar","Hyderabad1");
		Customer customer10 = new Customer("Anil","Hyderabad10");
		Customer customer11 = new Customer("Avinash","Hyderabad11");
		Customer customer12 = new Customer("Smith","Hyderabad12");
		Customer customer13 = new Customer("John","Hyderabad13");
		Customer customer14 = new Customer("Mark","Hyderabad14");
		Customer customer15 = new Customer("Bhoopal","Hyderabad15");
		
		//Java9 Style for Creating Immutable Collection
		List<Customer> customers = 
		List.of(customer1,customer2,customer3,customer4,customer5,
				customer6,customer7,customer8,customer9,customer10,
				customer11,customer12,customer13,customer14,customer15);
		

		return customers;
	}

}

OUTPUT
======
  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/

Hibernate: select count(*) from ashokit_customers c1_0
Hibernate: select * from (select c1_0.customer_id c0,c1_0.customer_location c1,c1_0.customer_name c2,row_number() over(order by c1_0.customer_name desc) rn from ashokit_customers c1_0) r_0_ where r_0_.rn<=?+? and r_0_.rn>? order by r_0_.rn
Hibernate: select count(c1_0.customer_id) from ashokit_customers c1_0

Page No :: 1 Records........
Customer [cutomerId=6, customerName=Yagnesh, customerLocation=Hyderabad6]
Customer [cutomerId=2, customerName=Suresh, customerLocation=Hyderabad2]
Customer [cutomerId=12, customerName=Smith, customerLocation=Hyderabad12]
Customer [cutomerId=9, customerName=Rameshwar, customerLocation=Hyderabad1]
Customer [cutomerId=4, customerName=Ramesh, customerLocation=Hyderabad4]
Hibernate: select * from (select c1_0.customer_id c0,c1_0.customer_location c1,c1_0.customer_name c2,row_number() over(order by c1_0.customer_name desc) rn from ashokit_customers c1_0) r_0_ where r_0_.rn<=?+? and r_0_.rn>? order by r_0_.rn
Hibernate: select count(c1_0.customer_id) from ashokit_customers c1_0

Page No :: 2 Records........
Customer [cutomerId=3, customerName=Rajesh, customerLocation=Hyderabad3]
Customer [cutomerId=8, customerName=Naresh, customerLocation=Hyderabad8]
Customer [cutomerId=5, customerName=Nagesh, customerLocation=Hyderabad5]
Customer [cutomerId=14, customerName=Mark, customerLocation=Hyderabad14]
Customer [cutomerId=1, customerName=Mahesh, customerLocation=Hyderabad1]
Hibernate: select * from (select c1_0.customer_id c0,c1_0.customer_location c1,c1_0.customer_name c2,row_number() over(order by c1_0.customer_name desc) rn from ashokit_customers c1_0) r_0_ where r_0_.rn<=?+? and r_0_.rn>? order by r_0_.rn
Hibernate: select count(c1_0.customer_id) from ashokit_customers c1_0

Page No :: 3 Records........
Customer [cutomerId=13, customerName=John, customerLocation=Hyderabad13]
Customer [cutomerId=7, customerName=Ganesh, customerLocation=Hyderabad7]
Customer [cutomerId=15, customerName=Bhoopal, customerLocation=Hyderabad15]
Customer [cutomerId=11, customerName=Avinash, customerLocation=Hyderabad11]
Customer [cutomerId=16, customerName=Ashok, customerLocation=Hyderabada16]
Hibernate: select * from (select c1_0.customer_id c0,c1_0.customer_location c1,c1_0.customer_name c2,row_number() over(order by c1_0.customer_name desc) rn from ashokit_customers c1_0) r_0_ where r_0_.rn<=?+? and r_0_.rn>? order by r_0_.rn

Page No :: 4 Records........
Customer [cutomerId=10, customerName=Anil, customerLocation=Hyderabad10]