Field "" in "" required a bean of type "" that could not be found

I'm struggling through a Spring Web API tutorial, using STS4.

I got to the state in the tutorial where I need to test it, but I just got a "not found", so the routing doesn't seem to be working.

I saw online comments that seem to suggest I need a @ComponentScan("com.example") adding to the main() function, something not mentioned in the tutorial.

So I did this but now I'm getting the following.

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

Description:

Field pollRepository in com.example.controller.PollController required a bean of type 'com.example.repository.PollRepository' that could not be found.

The injection point has the following annotations:
    - @javax.inject.Inject()


Action:

Consider defining a bean of type 'com.example.repository.PollRepository' in your configuration.

My project looks like this:

The main method (in QuickPollApplication.java):

package com.example.rest;

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

@ComponentScan("com.example")
@SpringBootApplication
public class QuickPollApplication {

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

}

and PollController.java looks like this:

package com.example.controller;

import javax.inject.Inject;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import com.example.domain.Poll;
import com.example.repository.PollRepository;

@RestController
public class PollController {

    @Inject
    private PollRepository pollRepository;
    
    @GetMapping("/polls")
    public ResponseEntity<Iterable<Poll>> getAllPolls() {
        Iterable<Poll> allPolls = pollRepository.findAll();
        return new ResponseEntity<>(allPolls, HttpStatus.OK);
    }
}

and this is PollRepository.java:

package com.example.repository;

import org.springframework.data.repository.CrudRepository;
import com.example.domain.Poll;


public interface PollRepository extends CrudRepository<Poll, Long> {

}

Let me know if it would be helpful to show anything else!

As per a suggestion I tried adding @EnableJpaRepositories(basePackages="com.example") to the QuickPollApplication class, but this just resulted in more errors, starting with:

Error creating bean with name 'pollController': Unsatisfied dependency expressed through field 'pollRepository'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'pollRepository' defined in com.example.repository.PollRepository defined in @EnableJpaRepositories declared on QuickPollApplication: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class com.example.domain.Poll

Can you move application main class to com.example package instead?

If not, You can try adding
@EnableJpaRepositories(basePackages="com.example") to QuickPollApplication class.

Also you require additional config like @EntityScan with base packages configured.

Explaination:

By default, Spring Boot enables JPA repository support and looks in the package (and its subpackages) where @SpringBootApplication is located. If your configuration has JPA repository interface definitions located in a package that is not visible, you can point out alternate packages by using @EnableJpaRepositories and its type-safe basePackageClasses=MyRepository.class parameter.

Ref: https://spring.io/guides/gs/accessing-data-jpa/