How can we create Auto generated field or ID for mongodb using spring boot

• 😂 How can we create an Auto-generated field or ID for MongoDB using spring boot?

First Create One Application Like Mongodb_sequence-id-generator

Pom.XML

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-mongodb</artifactId> </dependency> <dependency> <groupId>de.flapdoodle.embed</groupId> <artifactId>de.flapdoodle.embed.mongo</artifactId> </dependency>

• User.java

package com.app; import org.springframework.data.annotation.Id; import org.springframework.data.annotation.Transient; import org.springframework.data.mongodb.core.mapping.Document; @Document(collection = "users_db") public class User { @Transient public static final String SEQUENCE_NAME = "users_sequence"; @Id private long id; private String firstName; private String lastName; private String email; public User() { } public User(String firstName, String lastName, String email) { this.firstName = firstName; this.lastName = lastName; this.email = email; } public long getId() { return id; } public void setId(long l) { this.id = l; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } @Override public String toString() { return "User{" + "id=" + id + ", firstName='" + firstName + '\'' + ", lastName='" + lastName + '\'' + ", email='" + email + '\'' + '}'; } }

• DatabaseSequence.java

package com.app; import org.springframework.data.annotation.Id; import org.springframework.data.mongodb.core.mapping.Document; import org.springframework.stereotype.Component; @Document(collection = "database_sequences") @Component public class DatabaseSequence { @Id private String id; private long seq; public DatabaseSequence() {} public String getId() { return id; } public void setId(String id) { this.id = id; } public long getSeq() { return seq; } public void setSeq(long seq) { this.seq = seq; } }

• UserRepositery.java

package com.app; import org.springframework.data.mongodb.repository.MongoRepository; import org.springframework.stereotype.Repository; @Repository public interface UserRepositery extends MongoRepository<User,Long>{ }

• SequenceGeneratorService.java

package com.app; import static org.springframework.data.mongodb.core.query.Query.query; import java.util.Objects; import static org.springframework.data.mongodb.core.FindAndModifyOptions.options; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Bean; import org.springframework.data.mongodb.core.MongoOperations; import org.springframework.data.mongodb.core.query.Update; import org.springframework.stereotype.Service; import static org.springframework.data.mongodb.core.query.Criteria.where; @Service public class SequenceGeneratorService { @Autowired private MongoOperations mongoOperations; @Autowired public SequenceGeneratorService(MongoOperations mongoOperations) { this.mongoOperations = mongoOperations; } public long generateSequence(String seqName) { DatabaseSequence counter = mongoOperations.findAndModify(query(where("_id").is(seqName)), new Update().inc("seq",1), options().returnNew(true).upsert(true), DatabaseSequence.class); return !Objects.isNull(counter) ? counter.getSeq() : 1; } }

• MongodbSequenceIdGenerator1Application: This do work like Controller Best of luck

package com.app; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.stereotype.Repository; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RestController; @SpringBootApplication @RestController public class MongodbSequenceIdGenerator1Application { @Autowired private UserRepositery repository; @Autowired private SequenceGeneratorService sequenceGeneratorService; @PostMapping("/save") public User saveUser(@RequestBody User user) { //set Id user.setId(sequenceGeneratorService.generateSequence(User.SEQUENCE_NAME)); return repository.save(user); } @GetMapping("/select") public List<User> getUser() { return repository.findAll(); } public static void main(String[] args) { SpringApplication.run(MongodbSequenceIdGenerator1Application.class, args); System.out.println("Project is started"); } }