Spring Boot @Mapper Bean creation issue : Application Failed to start. Error : Consider defining a bean of Type

Question

I am new to spring, when i try to do the mvn clean install of my project this problem appears:

Error

***************************
APPLICATION FAILED TO START
***************************

**Description**:

Field userService in com.example.accessingdatamysql.rest.MainController required a bean of type 'com.example.accessingdatamysql.service.UserService' that could not be found.

The injection point has the following annotations:
        - @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'com.example.accessingdatamysql.service.UserService' in your configuration.

The problem is that in the MainController there is the import of "UserService":

package com.example.accessingdatamysql.rest;





import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.example.accessingdatamysql.model.dto.UserDto;
import com.example.accessingdatamysql.service.UserService;


@RestController
public class MainController {
  @Autowired 
         
private UserService userService;

  @Transactional
  @PostMapping(path="/demo/add")
  public @ResponseBody String addNewUser (@RequestParam String name
      , @RequestParam String email,@RequestParam String surname) 
  {
 

    UserDto n = new UserDto();
    n.setName(name);
    n.setSurname(surname);
    n.setEmail(email);
    userService.create(n);
    return "Saved";
  }



 


  @GetMapping("/demo/first")
  public UserDto one(@RequestParam String name) {
   System.out.print(name);
  return userService.findFirstByName(name); 
  }
}
  

It is probably a trivial thing but I can not bypass the problem, below I insert "UserService" and the MainStart

UserService.java

package com.example.accessingdatamysql.service;

import com.example.accessingdatamysql.model.dto.UserDto;

public interface UserService {

    UserDto findFirstByName(String name);
    
    void create(UserDto user);
        
}

UPDATE : I insert the UserServiceImpl and the new main and Mapper, with the new error.

UserServiceImpl.java

package com.example.accessingdatamysql.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.example.accessingdatamysql.model.dto.UserDto;
import com.example.accessingdatamysql.model.entity.UserEntity;
import com.example.accessingdatamysql.model.repo.UserRepository;
import com.example.accessingdatamysql.util.UserMapper;

@Service
public class UserServiceImpl implements UserService{
    
    @Autowired
      private UserRepository userRepository;
    
    @Autowired
    UserMapper mapper;

    @Override
    public UserDto findFirstByName(String name) {
           UserEntity entity = userRepository.findFirstByName(name);
           
        return mapper.toDtoMapper(entity);
    }

    @Override
    public void create(UserDto user) {
         UserEntity entity = mapper.toEntityMapper(user);
         
         userRepository.create(entity);
        
    }
 
}

AccessingDataMysqlApplication.java

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.ComponentScan;


@SpringBootApplication(scanBasePackages = { "com.example.accessingdatamysql",
"com.example.accessingdatamysql.util"})
public class AccessingDataMysqlApplication {

  public static void main(String[] args) {
    SpringApplication.run(AccessingDataMysqlApplication.class, args);
  }

}

UserMapper.java

package com.example.accessingdatamysql.util;

import org.mapstruct.Mapper;

import com.example.accessingdatamysql.model.dto.UserDto;
import com.example.accessingdatamysql.model.entity.UserEntity;


@Mapper (componentModel = "spring")
public interface UserMapper {

    UserEntity toEntityMapper (UserDto user);
    
    UserDto toDtoMapper (UserEntity userEntity);
}

New Error:

***************************
APPLICATION FAILED TO START
***************************

Description:

Field mapper in com.example.accessingdatamysql.service.UserServiceImpl required a bean of type 'com.example.accessingdatamysql.util.UserMapper' that could not be found.

The injection point has the following annotations:
        - @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'com.example.accessingdatamysql.util.UserMapper' in your configuration.

POM

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>accessingdatamysql</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>project</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
            </properties>

    <dependencies>
            <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct</artifactId>
            <version>1.3.1.Final</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Answer 1

You need to define a bean to let the Spring use them such as DI(Dependency Injection) @Autowired in this case.

There are various ways to define the beans but in your case using @Service annotation on the service class so that Spring can find it during the initialization.

And you don't need to declare @ComponentScan annotation the @SpringbootApplication will handle everything.

As @Som said, you need to implement your Userservice class since it is interface and there is no implemented class yet.

Try to remove @ComponentScan annotation and implement UserService interface as follow

@Service
public class UserServiceImpl implements UserService{
    // the rest of the code
}