1 introduction

Springboot is the easiest way to use Spring, and MongoDB is the most popular NoSQL database. Both of them are highly used in distributed and micro-service architecture. This paper will introduce how to integrate MongoDB in Springboot with examples: MongoRepository and MongoTemplate.

The code structure is as follows:

2 Project Preparation

2.1 Starting the MongoDB Instance

For convenience, use Docker to start MongoDB, detailed guidance document please refer to: use Docker to install a MongoDB latest version of play, here no further details.

2.2 Introducing dependencies

The main dependencies are Web and MongoDB starter. Add the following code to pom.xml:

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>Copy the code

2.3 Configuring Database Connection Information

As with MySQL or Oracle, MongoDB also needs to configure connection information, as shown in application.properties:

server.port=8080

spring.data.mongodb.authentication-database=admin
spring.data.mongodb.database=testdb
spring.data.mongodb.username=user
spring.data.mongodb.password=123456
spring.data.mongodb.host=localhost
spring.data.mongodb.port=27017Copy the code

2.4 Create data model entities

Create User class as follows:

package com.pkslow.mongo.model; import org.springframework.data.annotation.Id; import java.util.Date; public class User { @Id private String userId; private String name; private Integer age; private Date createTime = new Date(); public String getUserId() { return userId; } public void setUserId(String userId) { this.userId = userId; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public Date getCreateTime() { return createTime; } public void setCreateTime(Date createTime) { this.createTime = createTime; }}Copy the code

There is no need to create a corresponding Collections (table) in MongoDB, which will be created automatically when new Collections are added via the Web application.

3 Method 1: MongoRepository

3.1 Define the data access layer UserRepository

As anyone who has used Spring Jpa knows, Repository is actually a class for manipulating databases. The same is true in the integration of the non-relational MongoDB database. Spring will help us implement the corresponding interface method, developers do not even need to write SQL, very easy. The code is as follows:

package com.pkslow.mongo.dal;

import com.pkslow.mongo.model.User;
import org.springframework.data.mongodb.repository.MongoRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository extends MongoRepository<User, String> {
}Copy the code

MongoRepository: MongoRepository:

,>
,>

3.2 implement the Controller

Controller is more basic, I will not explain, common annotations are necessary to master, directly on the code:

package com.pkslow.mongo.contrlloer; import com.pkslow.mongo.dal.UserRepository; import com.pkslow.mongo.model.User; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.*; import java.util.List; @RestController @RequestMapping("/user") public class UserController { @Autowired private final UserRepository userRepository; public UserController(UserRepository userRepository) { this.userRepository = userRepository; } @GetMapping("") public List<User> getAllUsers() { return userRepository.findAll(); } @GetMapping("/{userId}") public User getByUserId(@PathVariable String userId) { return userRepository.findById(userId).orElse(new User()); } @PostMapping("") public User addNewUser(@RequestBody User user) { return userRepository.save(user); } @DeleteMapping("/{userId}") public String delete(@PathVariable String userId) { User user = new User(); user.setUserId(userId); userRepository.deleteById(userId); return "deleted: " + userId; } @PutMapping("") public User update(@RequestBody User user) { return userRepository.save(user); }}Copy the code

Note that the code does not handle exceptions, so I’ll leave them out for a quick demonstration.

3.3 test

After the Postman test, each interface is successfully invoked. I’m not going to do a screenshot.

MongoTemplate mode 2: MongoTemplate

4.1 Define the data access layer UserDAL

Define the interface as:

package com.pkslow.mongo.dal;

import com.pkslow.mongo.model.User;
import java.util.List;

public interface UserDAL {
    List<User> findAll();

    User findById(String userId);

    User save(User user);

    void deleteById(String userId);
}Copy the code

Then implement the interface as follows:

package com.pkslow.mongo.dal; import com.pkslow.mongo.model.User; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.mongodb.core.MongoTemplate; import org.springframework.data.mongodb.core.query.Criteria; import org.springframework.data.mongodb.core.query.Query; import org.springframework.stereotype.Repository; import java.util.List; @Repository public class UserDALImpl implements UserDAL { @Autowired private MongoTemplate template; @Override public List<User> findAll() { return template.findAll(User.class); } @Override public User findById(String userId) { return template.findById(userId,User.class); } @Override public User save(User user) { return template.save(user); } @Override public void deleteById(String userId) { Query query = new Query(); query.addCriteria(Criteria.where("userId").is(userId)); template.remove(query, User.class); }}Copy the code

4.2 Implement another Controller

The code of this Controller is basically the same as before, except for the data access class. The code is as follows:

package com.pkslow.mongo.contrlloer; import com.pkslow.mongo.dal.UserDAL; import com.pkslow.mongo.model.User; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.*; import java.util.List; @RestController @RequestMapping("/userTemplate") public class UserTemplateController { @Autowired private final UserDAL userDAL; public UserTemplateController(UserDAL userDAL) { this.userDAL = userDAL; } @GetMapping("") public List<User> getAllUsers() { return userDAL.findAll(); } @GetMapping("/{userId}") public User getByUserId(@PathVariable String userId) { return userDAL.findById(userId); } @PostMapping("") public User addNewUser(@RequestBody User user) { return userDAL.save(user); } @DeleteMapping("/{userId}") public String delete(@PathVariable String userId) { User user = new User(); user.setUserId(userId); userDAL.deleteById(userId); return "deleted: " + userId; } @PutMapping("") public User update(@RequestBody User user) { return userDAL.save(user); }}Copy the code

4.3 test

The tests, too, all passed:

5 concludes

This article explains how to integrate Springboot and MongoDB through examples. There are two main methods: MongoRepository and MongoTemplate. The code has been posted in this article. If it is not clear, you can reply

to get the code.

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