Spring Boot Thymeleaf CRUD Database Real-Time Project - PART 7 | Sorting with Spring Data JPA

In this PART 7, we will implement Sorting for our employee list page using Spring Data JPA and Thymeleaf.

Use the below links to navigate different parts of this tutorial:

1. Spring Boot Thymeleaf CRUD Database Real-Time Project - PART 1
  • Create and Setup Spring Boot Project in Eclipse STS
  • Database Setup
7. Spring Boot Thymeleaf CRUD Database Real-Time Project - PART 7 
  • Implement Sorting Feature

Understand Spring Data JPA’s Sorting API

The Spring Data JPA provides PagingAndSortingRepository interface which supports spring and pagination with the following APIs:
@NoRepositoryBean
public interface PagingAndSortingRepository < T, ID > extends CrudRepository < T, ID > {

    /**
     * Returns all entities sorted by the given options.
     *
     * @param sort
     * @return all entities sorted by the given options
     */
    Iterable < T > findAll(Sort sort);

    /**
     * Returns a {@link Page} of entities meeting the paging restriction provided in the {@code Pageable} object.
     *
     * @param pageable
     * @return a page of entities
     */
    Page < T > findAll(Pageable pageable);
}
The users will be able to sort the employee's list by clicking on the column header of the table. 
First, create a Sort object like this:
Sort sort = Sort.by(“fieldName”).ascending();
This will sort the result by fieldName in ascending order. fieldName must match a field name declared in the entity class. 
We can also sort by more than one field, for example:
Sort sort = Sort.by("fieldName1").ascending().and(Sort.by("fieldName2").descending());
Then we pass the Sort object to create a Pageable as follows:
Pageable pageable = PageRequest.of(pageNum - 1, pageSize, sort);
Let's understand more in the example section.

1. Back-end changes

1. EmployeeService.java interface changes

Let's add two fields to the existing method:
Page<Employee> findPaginated(int pageNo, int pageSize, String sortField, String sortDirection);
The complete code:
package net.javaguides.springboot.service;

import java.util.List;

import org.springframework.data.domain.Page;

import net.javaguides.springboot.model.Employee;

public interface EmployeeService {
    List < Employee > getAllEmployees();
    void saveEmployee(Employee employee);
    Employee getEmployeeById(long id);
    void deleteEmployeeById(long id);
    Page < Employee > findPaginated(int pageNo, int pageSize, String sortField, String sortDirection);
}

2. EmployeeServiceImpl.java class changes

The sorting logic implemented in the below method:
@Override
public Page<Employee> findPaginated(int pageNo, int pageSize, String sortField, String sortDirection) {
 Sort sort = sortDirection.equalsIgnoreCase(Sort.Direction.ASC.name()) ? Sort.by(sortField).ascending() :
  Sort.by(sortField).descending();
 
 Pageable pageable = PageRequest.of(pageNo - 1, pageSize, sort);
 return this.employeeRepository.findAll(pageable);
}
The complete code:
package net.javaguides.springboot.service;

import java.util.List;
import java.util.Optional;

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

import net.javaguides.springboot.model.Employee;
import net.javaguides.springboot.repository.EmployeeRepository;

@Service
public class EmployeeServiceImpl implements EmployeeService {

    @Autowired
    private EmployeeRepository employeeRepository;

    @Override
    public List < Employee > getAllEmployees() {
        return employeeRepository.findAll();
    }

    @Override
    public void saveEmployee(Employee employee) {
        this.employeeRepository.save(employee);
    }

    @Override
    public Employee getEmployeeById(long id) {
        Optional < Employee > optional = employeeRepository.findById(id);
        Employee employee = null;
        if (optional.isPresent()) {
            employee = optional.get();
        } else {
            throw new RuntimeException(" Employee not found for id :: " + id);
        }
        return employee;
    }

    @Override
    public void deleteEmployeeById(long id) {
        this.employeeRepository.deleteById(id);
    }

    @Override
    public Page < Employee > findPaginated(int pageNo, int pageSize, String sortField, String sortDirection) {
        Sort sort = sortDirection.equalsIgnoreCase(Sort.Direction.ASC.name()) ? Sort.by(sortField).ascending() :
            Sort.by(sortField).descending();

        Pageable pageable = PageRequest.of(pageNo - 1, pageSize, sort);
        return this.employeeRepository.findAll(pageable);
    }
}

3.EmployeeController.java changes

Let's change the existing method to provide a support for sorting:
@GetMapping("/page/{pageNo}")
public String findPaginated(@PathVariable(value = "pageNo") int pageNo,
    @RequestParam("sortField") String sortField,
    @RequestParam("sortDir") String sortDir,
    Model model) {
    int pageSize = 5;

    Page < Employee > page = employeeService.findPaginated(pageNo, pageSize, sortField, sortDir);
    List < Employee > listEmployees = page.getContent();

    model.addAttribute("currentPage", pageNo);
    model.addAttribute("totalPages", page.getTotalPages());
    model.addAttribute("totalItems", page.getTotalElements());

    model.addAttribute("sortField", sortField);
    model.addAttribute("sortDir", sortDir);
    model.addAttribute("reverseSortDir", sortDir.equals("asc") ? "desc" : "asc");

    model.addAttribute("listEmployees", listEmployees);
    return "index";
}
Also provide default sorting field and sorting direction for home page:
    // display list of employees
    @GetMapping("/")
    public String viewHomePage(Model model) {
        return findPaginated(1, "firstName", "asc", model);
    }
The complete code:
package net.javaguides.springboot.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;

import net.javaguides.springboot.model.Employee;
import net.javaguides.springboot.service.EmployeeService;

@Controller
public class EmployeeController {

    @Autowired
    private EmployeeService employeeService;

    // display list of employees
    @GetMapping("/")
    public String viewHomePage(Model model) {
        return findPaginated(1, "firstName", "asc", model);
    }

    @GetMapping("/showNewEmployeeForm")
    public String showNewEmployeeForm(Model model) {
        // create model attribute to bind form data
        Employee employee = new Employee();
        model.addAttribute("employee", employee);
        return "new_employee";
    }

    @PostMapping("/saveEmployee")
    public String saveEmployee(@ModelAttribute("employee") Employee employee) {
        // save employee to database
        employeeService.saveEmployee(employee);
        return "redirect:/";
    }

    @GetMapping("/showFormForUpdate/{id}")
    public String showFormForUpdate(@PathVariable(value = "id") long id, Model model) {

        // get employee from the service
        Employee employee = employeeService.getEmployeeById(id);

        // set employee as a model attribute to pre-populate the form
        model.addAttribute("employee", employee);
        return "update_employee";
    }

    @GetMapping("/deleteEmployee/{id}")
    public String deleteEmployee(@PathVariable(value = "id") long id) {

        // call delete employee method 
        this.employeeService.deleteEmployeeById(id);
        return "redirect:/";
    }


    @GetMapping("/page/{pageNo}")
    public String findPaginated(@PathVariable(value = "pageNo") int pageNo,
        @RequestParam("sortField") String sortField,
        @RequestParam("sortDir") String sortDir,
        Model model) {
        int pageSize = 5;

        Page < Employee > page = employeeService.findPaginated(pageNo, pageSize, sortField, sortDir);
        List < Employee > listEmployees = page.getContent();

        model.addAttribute("currentPage", pageNo);
        model.addAttribute("totalPages", page.getTotalPages());
        model.addAttribute("totalItems", page.getTotalElements());

        model.addAttribute("sortField", sortField);
        model.addAttribute("sortDir", sortDir);
        model.addAttribute("reverseSortDir", sortDir.equals("asc") ? "desc" : "asc");

        model.addAttribute("listEmployees", listEmployees);
        return "index";
    }
}

2. Front-end changes

1.index.html

We make the header columns of the table sortable by adding hyperlinks with the following code:
<th>
      <a th:href="@{'/page/' + ${currentPage} + '?sortField=firstName&sortDir=' + ${reverseSortDir}}">
       Employee First Name</a>
     </th>
     <th>
     <a th:href="@{'/page/' + ${currentPage} + '?sortField=lastName&sortDir=' + ${reverseSortDir}}">
       Employee Last Name</a>
     </th>
     <th>
     <a th:href="@{'/page/' + ${currentPage} + '?sortField=email&sortDir=' + ${reverseSortDir}}">
       Employee Email</a>
     </th>
     <th> Actions </th>
We also need to change pagination part to provide sorting support like:
<div th:if = "${totalPages > 1}">
   <div class = "row col-sm-10">
    <div class = "col-sm-2">
     Total Rows: [[${totalItems}]] 
    </div>
    <div class = "col-sm-1">
     <span th:each="i: ${#numbers.sequence(1, totalPages)}">
      <a th:if="${currentPage != i}" th:href="@{'/page/' + ${i}+ '?sortField=' + ${sortField} + '&sortDir=' + ${sortDir}}">[[${i}]]</a>
      <span th:unless="${currentPage != i}">[[${i}]]</span>  &nbsp; &nbsp;
     </span>
    </div>
    <div class = "col-sm-1">
     <a th:if="${currentPage < totalPages}" th:href="@{'/page/' + ${currentPage + 1}+ '?sortField=' + ${sortField} + '&sortDir=' + ${sortDir}}">Next</a>
     <span th:unless="${currentPage < totalPages}">Next</span>
    </div>
    
     <div class="col-sm-1">
        <a th:if="${currentPage < totalPages}" th:href="@{'/page/' + ${totalPages}+ '?sortField=' + ${sortField} + '&sortDir=' + ${sortDir}}">Last</a>
     <span th:unless="${currentPage < totalPages}">Last</span>
        </div>
   </div>
  </div>
The complete code:
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="ISO-8859-1">
<title>Employee Management System</title>

<link rel="stylesheet"
 href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css"
 integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO"
 crossorigin="anonymous">
 
</head>
<body>

 <div class="container my-2">
 <h1>Employees List</h1>
 
 <a th:href = "@{/showNewEmployeeForm}" class="btn btn-primary btn-sm mb-3"> Add Employee </a>
 
  <table border="1" class = "table table-striped table-responsive-md">
   <thead>
    <tr>
     <th>
      <a th:href="@{'/page/' + ${currentPage} + '?sortField=firstName&sortDir=' + ${reverseSortDir}}">
       Employee First Name</a>
     </th>
     <th>
     <a th:href="@{'/page/' + ${currentPage} + '?sortField=lastName&sortDir=' + ${reverseSortDir}}">
       Employee Last Name</a>
     </th>
     <th>
     <a th:href="@{'/page/' + ${currentPage} + '?sortField=email&sortDir=' + ${reverseSortDir}}">
       Employee Email</a>
     </th>
     <th> Actions </th>
    </tr>
   </thead>
   <tbody>
    <tr th:each="employee : ${listEmployees}">
     <td th:text="${employee.firstName}"></td>
     <td th:text="${employee.lastName}"></td>
     <td th:text="${employee.email}"></td>
     <td> <a th:href="@{/showFormForUpdate/{id}(id=${employee.id})}" class="btn btn-primary">Update</a>
         <a th:href="@{/deleteEmployee/{id}(id=${employee.id})}" class="btn btn-danger">Delete</a>
     </td>
    </tr>
   </tbody>
  </table>
  
  <div th:if = "${totalPages > 1}">
   <div class = "row col-sm-10">
    <div class = "col-sm-2">
     Total Rows: [[${totalItems}]] 
    </div>
    <div class = "col-sm-1">
     <span th:each="i: ${#numbers.sequence(1, totalPages)}">
      <a th:if="${currentPage != i}" th:href="@{'/page/' + ${i}+ '?sortField=' + ${sortField} + '&sortDir=' + ${sortDir}}">[[${i}]]</a>
      <span th:unless="${currentPage != i}">[[${i}]]</span>  &nbsp; &nbsp;
     </span>
    </div>
    <div class = "col-sm-1">
     <a th:if="${currentPage < totalPages}" th:href="@{'/page/' + ${currentPage + 1}+ '?sortField=' + ${sortField} + '&sortDir=' + ${sortDir}}">Next</a>
     <span th:unless="${currentPage < totalPages}">Next</span>
    </div>
    
     <div class="col-sm-1">
        <a th:if="${currentPage < totalPages}" th:href="@{'/page/' + ${totalPages}+ '?sortField=' + ${sortField} + '&sortDir=' + ${sortDir}}">Last</a>
     <span th:unless="${currentPage < totalPages}">Last</span>
        </div>
   </div>
  </div>
 </div>
</body>
</html>

3. Run Spring boot application and demo








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