Spring Boot Application With Spring REST and Spring Data MongoDB

In this article, we will create a simple Spring Boot application that performs CRUD operations with Spring REST and MongoDB.

Vanitha P K

Apr. 04, 24 · Tutorial

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MongoDB is a powerful, open-source, document-oriented database management system known for its flexibility, scalability, and wide range of features. It's part of the NoSQL family of database systems, designed to handle large volumes of data and to provide high performance, high availability, and easy scalability. MongoDB stores data in JSON-like documents in key-value pairs, which allows Java Spring Boot to leverage JSON structure in the code.

Spring Boot With MongoDB

We may come across situations where we use Spring boot with SQL databases, but to leverage MongoDB with Spring boot, Spring Data MongoDB offers lightweight repository data access and support for the MongoDB database, which reduces the complexity of the code.

Assuming that you have quite a good understanding of MongoDB, we will take a quick look at building a Spring Boot application with Spring Data MongoDB.

Prerequisites

Java
IDE of your choice

6 Steps to Creating a Spring Boot Application With Spring REST and Spring Data MongoDB

In this article, I have used the MongoDB Atlas database, which is a multi-cloud developer database service that allows you to create and maintain databases on the cloud, free of cost. I also used MongoDB Compass, a GUI tool to visualize the database. If you don't have an account for MongoDB Atlas, you can try it for free.

Step 1: Create a Spring Boot Application With Spring Initializer

First, you'll want to create a Spring Boot application using Spring Initializr, which generates a Spring Boot project with selected dependencies. Once you have selected the fields as shown in the image below, click on Generate, and import the extracted project in your IDE.

Project Structure:

Project structure with "Student" highlighted

Step 2: Configure the Database

To configure MongoDB in the Spring boot application, we are going to add the database URL in the src/main/resources/application.properties file as shown below:

Properties files

spring.data.mongodb.uri = mongodb+srv://username:[email protected]/student

Model:

MongoDB is a non-relational, document-oriented database. We have created a Student and Address Java model to store objects. @Document annotation is used to provide the custom collection name, and @Field is used to provide the custom key name for the object.

In the below code, we have created an example of variables with different data types like Date, List, etc.

Student.java

    Java
   
 

   package com.example.studentmanagementsystem.model;

import com.fasterxml.jackson.annotation.JsonFormat;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.index.Indexed;
import org.springframework.data.mongodb.core.mapping.Document;
import org.springframework.data.mongodb.core.mapping.Field;

import java.time.LocalDate;
import java.util.List;

@Document("Student")
public class Student {
    @Id
    @Indexed(unique = true)
    private String id;
    private String name;
    private double cgpa;
    @Field("has_arrears")
    private boolean hasArrears;
    @Field("course_list")
    private List courseList;
    private Address address;
    @Field("enrollment_date")
    @JsonFormat
            (shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy")
    private LocalDate enrollmentDate;
}
  

Address.java

    Java
   
 

   package com.example.studentmanagementsystem.model;

import jakarta.persistence.Entity;
import org.springframework.data.mongodb.core.mapping.Field;

@Entity
public class Address {
    private String street;
    private String city;
    private String state;
    private String country;
    @Field("zip_code")
    private String zipcode;
}
  

Step 3: Create the Repository

We have created an interface StudentRepository, which extends to MongoRepository. MongoRepository is an interface provided by Spring Data that allows pre-defined CRUD operations and automatic mapping. CRUD or REST operations are nothing but communication between services and data in a persistent and structured way.

Spring @Repository annotation is used to indicate that the class provides the mechanism for storage, retrieval, search, update, and delete operations on objects and acts as the persistence layer.

Let's create findBy methods to fetch data from the database as shown in the code below:

    Java
   
 

   package com.example.studentmanagementsystem.repository;
import com.example.studentmanagementsystem.model.Student;
import org.springframework.data.mongodb.repository.Aggregation;
import org.springframework.data.mongodb.repository.MongoRepository;
import org.springframework.stereotype.Repository;
import java.time.LocalDate;
import java.util.List;

@Repository
public interface StudentRepository extends MongoRepository {
    List findByNameAndCgpa(String name, Double cgpa);

    Student findByAddress_City(String city);

    List findByAddress_CountryOrHasArrears(String country, Boolean hasArrears);

    List findByEnrollmentDateBetweenOrderByEnrollmentDate(LocalDate startDate, LocalDate endDate);

    List findByCgpaGreaterThanEqual(Double cgpa);

    String findByNameIgnoreCase(String name);

    List findByCgpaOrderByNameDesc(Double cgpa, String name);
  
//aggregation example for overall average cgpa
    @Aggregation("{ $group : { _id : null, averageCgpa : { $avg : $cgpa} } }")
    Long avgCgpa();

}

  

Step 4: Create a Service

Let's build a service layer for the Student repository in order to communicate with the data in the MongoDB database. We will create a few methods to leverage CRUD operations like insert, retrieve, and delete methods.

    Java
   
 

   package com.example.studentmanagementsystem.service;

import com.example.studentmanagementsystem.model.Student;
import com.example.studentmanagementsystem.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.time.LocalDate;
import java.util.List;
import java.util.Optional;

@Service
public class StudentService {
    @Autowired
    private StudentRepository studentRepo;

    public void addStudentData(Student studentDetails) {
        studentRepo.insert(studentDetails);
    }

    public void addMultipleStudentsData(List studentsDetail) {
        studentRepo.insert(studentsDetail);
    }

    public List fetchAllStudentsData() {
        return studentRepo.findAll();
    }

    public Optional fetchStudentDataById(String id) {
        return studentRepo.findById(id);
    }

    public List fetchStudentDataByNameAndCgpa(String name, Double cgpa) {
        return studentRepo.findByNameAndCgpa(name, cgpa);
    }

    public Student fetchStudentDataByCity(String city) {
        return studentRepo.findByAddress_City(city);
    }

    public List fetchStudentDataByCountryOrArrears(String country, Boolean hasArrears) {
        return studentRepo.findByAddress_CountryOrHasArrears(country, hasArrears);
    }

    public List fetchStudentDataByCgpa(Double cgpa) {
        return studentRepo.findByCgpaGreaterThanEqual(cgpa);
    }

    public List fetchStudentDataByEnrollmentDate(LocalDate startDate, LocalDate endDate) {
        return studentRepo.findByEnrollmentDateBetweenOrderByEnrollmentDate(startDate, endDate);
    }

    public List fetchStudentDataByCgpaAndName(Double cgpa, String name) {
        return studentRepo.findByCgpaOrderByNameDesc(cgpa, name);
    }

    public Long fetchAverageCgpa() {
        return studentRepo.avgCgpa();
    }

    public String fetchStudentDataByName(String name) {
        return studentRepo.findByNameIgnoreCase(name);
    }

    public void deleteStudentData(Student studentDetails) {
        studentRepo.insert(studentDetails);
    }

    public void deleteAllStudentData() {
        studentRepo.deleteAll();
    }
}
  

Step 5: Create a Controller

Next, build CRUD REST API calls for the Student resource to fetch, insert, or delete resources in the MongoDB database.

The Spring @RestController annotation is used to create RESTful web services, and it combines both @Controller and @Responsebody annotations, making it easy to write handler methods.

    Java
   
 

   package com.example.studentmanagementsystem.controller;

import com.example.studentmanagementsystem.model.Student;
import com.example.studentmanagementsystem.service.StudentService;
import com.fasterxml.jackson.annotation.JsonFormat;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.time.LocalDate;
import java.util.List;
import java.util.Optional;

@RestController
@RequestMapping("/student")
public class StudentController {
    @Autowired
    private StudentService studentService;

    @PostMapping("/addStudent")
    public void populateStudentData(@RequestBody Student student){
          studentService.addStudentData(student);
    }

    @PostMapping("/addStudentsData")
    public void populateStudentsData(@RequestBody List students){
        studentService.addMultipleStudentsData(students);
    }

    @GetMapping("/getAllStudentsData")
    public List fetchAllStudentsData(){
        return studentService.fetchAllStudentsData();
    }

    @GetMapping("/getStudentById/{id}")
    public Optional fetchStudentDataById(@PathVariable String id){
       return studentService.fetchStudentDataById(id);
    }
    @GetMapping("/getStudentByNameAndCgpa")
    public List fetchStudentDataByNameAndCgpa(@RequestParam String name, @RequestParam Double cgpa){
        return studentService.fetchStudentDataByNameAndCgpa(name, cgpa);
    }
    @GetMapping("/getStudentByCity/{city}")
    public Student fetchStudentDataByCity(@PathVariable String city){
        return studentService.fetchStudentDataByCity(city);
    }
    @GetMapping("/getStudentByCountryOrArrears")
    public List fetchStudentDataByCountryOrArrears(@RequestParam String country,@RequestParam Boolean hasArrears){
        return studentService.fetchStudentDataByCountryOrArrears(country, hasArrears);
    }
    @GetMapping("/getStudentByEnrollmentDate")
    public List fetchStudentDataByEnrollmentDate(@JsonFormat
                                                                      (shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy") LocalDate startDate, @JsonFormat
            (shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy") LocalDate endDate){
        return studentService.fetchStudentDataByEnrollmentDate(startDate, endDate);
    }
    @GetMapping("/getStudentByName")
    public String fetchStudentDataByName(@RequestParam String name){
        return studentService.fetchStudentDataByName(name);
    }
    @GetMapping("/getStudentByCgpa")
    public List fetchStudentDataByCgpa(@RequestParam Double cgpa){
        return studentService.fetchStudentDataByCgpa(cgpa);
    }
    @GetMapping("/getAvgCgpa")
    public Long fetchStudentAvgCgpa(){
        return studentService.fetchAverageCgpa();
    }
    @DeleteMapping("/deleteStudent")
    public void deleteStudentData(Student student){
        studentService.deleteStudentData(student);
    }

    @DeleteMapping("/deleteAllStudents")
    public void deleteAllStudentsData(){
        studentService.deleteAllStudentData();
    }
}

  

Step 6: Testing

Now, let's test one of the API calls in Postman to fetch data from the database as shown in the below image.

The below HTTP method returns all the student information in an array of JSON objects.

Method: GET

Request URL: http://localhost:8080/student/getAllStudentsData

Fetching data from the database using Postman

We have built a Spring Boot application leveraging the MongoDB database, and we have created CRUD operations such as creating, deleting, and fetching the data from the database, including different ways to fetch data. Spring Data MongoDB helps us to use the inbuilt methods for CRUD operations, which reduces the code complexity in the persistence layer.

MongoDB REST Spring Data application Data (computing) Spring Boot

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