This Spring boot tutorial will teach you how to do basic database functions that are CREATE RETIEVE, UPDATE and DELETE and SEARCH using mongoDB Database.

Crud function how to perform the RESTful Web Service let discuss with following annotations.

@PostMapping:  annotation which used to create new record.
@GetMapping:   annotation which used to reads a record.
@RequestMapping: annotation which used to search the record.
@PutMapping:   annotation which used to update the existing record.
@DeleteMapping:  annotation which used to delete the record.

First Create the Controller

StudentController

package com.example.SpringMongoProject.Controller;

import com.example.SpringMongoProject.Entity.Student;
import com.example.SpringMongoProject.Service.StudentServices;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
@CrossOrigin(origins = "*")
@RequestMapping("api/v1/student")
public class StudentController {

    @Autowired
    private StudentServices studentServices;

    @PostMapping(value = "/save")
    private String saveStudent(@RequestBody Student students) {

        studentServices.saveorUpdate(students);
        return students.get_id();
    }
    
    @GetMapping(value = "/getall")
    public Iterable<Student> getStudents() {
        return studentServices.listAll();
    }

    @PutMapping(value = "/edit/{id}")
    private Student update(@RequestBody Student student, @PathVariable(name = "id") String _id) {
        student.set_id(_id);
        studentServices.saveorUpdate(student);
        return student;
    }

    @DeleteMapping("/delete/{id}")
    private void deleteStudent(@PathVariable("id") String _id) {
        studentServices.deleteStudent(_id);
    }


    @RequestMapping("/search/{id}")
    private Student getStudents(@PathVariable(name = "id") String studentid) {
        return studentServices.getStudentByID(studentid);
    }

}

Create the Entity

Student

package com.example.SpringMongoProject.Entity;

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

@Document(collection ="students")
public class Student {

    @Id
    private String _id;
    private String studentname;
    private String studentaddress;
    private String mobile;


    public Student(String _id, String studentname, String studentaddress, String mobile) {
        this._id = _id;
        this.studentname = studentname;
        this.studentaddress = studentaddress;
        this.mobile = mobile;
    }


    public Student() {
    }

    public String get_id() {
        return _id;
    }

    public void set_id(String _id) {
        this._id = _id;
    }

    public String getStudentname() {
        return studentname;
    }

    public void setStudentname(String studentname) {
        this.studentname = studentname;
    }

    public String getStudentaddress() {
        return studentaddress;
    }

    public void setStudentaddress(String studentaddress) {
        this.studentaddress = studentaddress;
    }

    public String getMobile() {
        return mobile;
    }

    public void setMobile(String mobile) {
        this.mobile = mobile;
    }

    @Override
    public String toString() {
        return "Student{" +
                "_id='" + _id + '\'' +
                ", studentname='" + studentname + '\'' +
                ", studentaddress='" + studentaddress + '\'' +
                ", mobile='" + mobile + '\'' +
                '}';
    }
}

Create repository

StudentRepo

package com.example.SpringMongoProject.Repo;

import com.example.SpringMongoProject.Entity.Student;
import org.springframework.data.mongodb.repository.MongoRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface StudentRepo extends MongoRepository<Student,String> {
}

Create Service

StudentServices

package com.example.SpringMongoProject.Service;

import com.example.SpringMongoProject.Entity.Student;
import com.example.SpringMongoProject.Repo.StudentRepo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class StudentServices {

    @Autowired
    private StudentRepo repo;

    public void saveorUpdate(Student students) {

        repo.save(students);
    }

    public Iterable<Student> listAll() {

        return this.repo.findAll();
    }


    public void deleteStudent(String id) {

        repo.deleteById(id);
    }

    public Student getStudentByID(String studentid) {

        return repo.findById(studentid).get();
    }
}

i have attached the video link below. which will do this tutorials step by step.