In Spring boot application is #Component annotation optional for repo - spring-boot

Question

I have created the basic application using Spring boot using JPA. I have added #AutoWired annotation for RatingRepo in RatingResource, but haven't added #Component annotation to RatingRepo
package com.example.demo;
import java.util.Arrays;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.example.demo.RatingsRateService.model.Rating;
import com.example.demo.RatingsRateService.model.UserRating;
#RestController
#RequestMapping("ratingsdata")
public class RatingResource {
#Autowired
RatingRepo repo;
/*
* #RequestMapping("/{movieId}") public Rating
* getRating(#PathVariable("movieId") String movieId) { return new
* Rating(movieId,7); }
*/
#RequestMapping("users/{userid}")
public UserRating getRating(#PathVariable("userid") int userid) {
List<Rating> ratings =repo.findByUserId(userid);
/*
* List<Rating> ratings = Arrays.asList(new Rating("1",4), new Rating("2",3),
* new Rating("3",2));
*/
System.out.println(ratings);
UserRating userRating = new UserRating();
userRating.setUserRating(ratings);
return userRating;
}
}
package com.example.demo;
import java.util.List;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import com.example.demo.RatingsRateService.model.Rating;
//to update the data in database , created the interd=face and will implement
//class,primary key
public interface RatingRepo extends JpaRepository<Rating, Integer>{
#Query(" from Rating where userid = ?1")
List<Rating> findByUserId( int userid);
}
. Still, it is working fine. Can you someone please explain why it is so? Or it is not needed to add #Component annotation for the repo?

Answer 1

first of there is #Repository annotation required not #Component
and #Repository also auto configure due to below:
Probably you are using spring boot
Spring Data repositories usually extend from the Repository or CrudRepository interfaces. If you are using auto-configuration, repositories will be searched from the package containing your main configuration class (the one annotated with #EnableAutoConfiguration or #SpringBootApplication) down.
ref: https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-sql.html#boot-features-spring-data-jpa-repositories