'Field required a bean of type that could not

Question

So I've been learning Spring in the couples of week, been following this tutorial

Building a RESTful Web Service

All was well until I tried to integrate it to mongodb. So I follow this tutorial.

Accessing Data with MongoDB

But my practice is partially still using the first one. So my project directory structure is like this.

src/
├── main/
│   └── java/
|       ├── model/
|       |   └── User.java
|       ├── rest/
|       |   ├── Application.java
|       |   ├── IndexController.java
|       |   └── UsersController.java
|       └── service/
|           └── UserService.java
└── resources/
    └── application.properties

This is my model/User.java file

package main.java.model;

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

@Document(collection="user")
public class User {

    private int age;
    private String country; 
    @Id
    private String id;
    private String name;


    public User() {
        super();
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }
}

This is my rest/UsersController.java file

package main.java.rest;

import java.util.List;
import main.java.service.UserService;
import main.java.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping(value = "/users")
public class UsersController {

    @Autowired
    UserService userService;

    @RequestMapping(method = RequestMethod.GET)
    public List<User> getAllUsers() {
        return userService.findAll();
    }
}

This is my service/UserService.java file

package main.java.service;

import java.util.List;
import main.java.model.User;
import org.springframework.data.mongodb.repository.MongoRepository;

public interface UserService extends MongoRepository<User, String> {
    public List<User> findAll();
}

I could compile them (I'm using gradle for compilation because I'm following the tutorial), but when I run the jar file it was throwing this error.

---

APPLICATION FAILED TO START

---

Description:

Field userService in main.java.rest.UsersController required a bean of type 'main.java.service.UserService' that could not be found.

Action:

Consider defining a bean of type 'main.java.service.UserService' in your configuration.

Not sure what is wrong I start googling around and found that I need to include Beans.xml file and register the userService in it. I did that but it's not working. I'm really new to this so I really have no clue on what's going on.

Answer 1

In my case i have just put the Class MyprojectApplication in a package(com.example.start) with the same level of model, controller,service packages.

Answer 2

Add the @Component in your controller class. May this work

Answer 3

I have same Issue, fixed by Adding @EnableMongoRepositories("in.topthree.util")

package in.topthree.core;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;

import in.topthree.util.Student;

@SpringBootApplication
@EnableMongoRepositories("in.topthree.util")
public class Run implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(Run.class, args);
        System.out.println("Run");
    }

    @Autowired
    private Process pr;

    @Override
    public void run(String... args) throws Exception {
        pr.saveDB(new Student("Testing", "FB"));
        System.exit(0);
    }

}

And My Repository

 package in.topthree.util;

    import org.springframework.data.mongodb.repository.MongoRepository;

    public interface StudentMongo extends MongoRepository<Student, Integer> {

        public Student findByUrl(String url);
    }

Now Its Working

Answer 4

In my case, I accidentally defined the service class abstract while doing copy and paste.

@Serivce
@Valdiated
public abstract class MyService { // remove the abstract modifier!!!
}

Answer 5

Add the @Service in the service/UserService.java.

Answer 6

This may happen when two beans have same names.

Module1Beans.java：

@Configuration
public class Module1Beans {
    @Bean
    public GoogleAPI retrofitService(){
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://www.google.com/")
                .addConverterFactory(JacksonConverterFactory.create())
                .build();
        return retrofit.create(GoogleAPI.class);
    }
}

Module2Beans.java：

@Configuration
public class Module2Beans {
    @Bean
    public GithubAPI retrofitService(){
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://www.github.com/")
                .addConverterFactory(JacksonConverterFactory.create())
                .build();
        return retrofit.create(GithubAPI.class);
    }
}

A bean named retrofitService is first created, and it's type is GoogleAPI, then covered by a GithubAPI becauce they're both created by a retrofitService() method. Now when you @Autowired a GoogleAPI you'll get a message like Field googleAPI in com.example.GoogleService required a bean of type 'com.example.rest.GoogleAPI' that could not be found.