spring boot fails to start-- define a bean of type 'TopicRepository' in configuration - spring

Question

I was following this JavaBrains tutorials of Spring Boot.
My project structure is as follows:
CourseApiApp.java:
#SpringBootApplication
#ComponentScan(basePackages = {
"com.bloodynacho.rishab.topics"
})
#EntityScan("com.bloodynacho.rishab.topics")
public class CourseApiApp {
public static void main(String[] args) {
SpringApplication.run(CourseApiApp.class, args);
}
}
TopicController.java:
#RestController
public class TopicController {
#Autowired
private TopicService topicService;
#RequestMapping(
value = "/topics"
)
public List<Topic> getAllTopcs() {
return topicService.getAllTopics();
}
}
TopicService.java:
#Service
public class TopicService {
#Autowired
private TopicRepository topicRepository;
public List<Topic> getAllTopics() {
List<Topic> topics = new ArrayList<>();
this.topicRepository
.findAll()
.forEach(topics::add);
return topics;
}
}
Topic.java:
#Entity
public class Topic {
#Id
private String id;
private String name;
private String description;
}
TopicRepository.java:
#Repository
public interface TopicRepository extends CrudRepository<Topic, String>{
}
pom.xml:
<dependencies>
<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>org.apache.derby</groupId>
<artifactId>derby</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
I was using the lombok #Getter, #Getter and #AllArgsConstructor in Topic.java but I removed it after reading one of the answers here.
I read this1, this2, this3
Still, I get
***************************
APPLICATION FAILED TO START
***************************
Description:
Field topicRepository in com.bloodynacho.rishab.topics.TopicService required a bean of type 'com.bloodynacho.rishab.topics.TopicRepository' 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.bloodynacho.rishab.topics.TopicRepository' in your configuration.
Process finished with exit code 1
EDIT: I read this explaining how even without actually implementing the interface the #Autowired works. I understand the solution, but I don't understand how to solve my issue. Clearly, there is some problem with the way Spring Data is set up and configured (as mentioned in the answer)

Answer 1

Because if your other packages hierarchies are below your main application with the #SpringBootApplication annotation, you’re covered by implicit components scan.
Therefore, one simple solution can be done by following 2 steps:
Rename the package of main class to be com.bloodynacho.rishab.
(That is what I suggest that the complete package name of main app. is supposed to be root of other packages.)
Remove #ComponentScan and #EntityScan annotation.
(Although #ComponentScan is different from #EntityScan, it can be also removed in my experience.)