#24 simple sns: 좋아요 개수 api

simple_sns/src/main/java/com/example/sns/controller/PostController.java

@@ -61,4 +61,9 @@ public class PostController {
         return Response.success();
     }
 
+    @GetMapping("/{postId}/likes")
+    public Response<Integer> likeCount(@PathVariable Integer postId, Authentication authentication) {
+        return Response.success(postService.likeCount(postId));
+    }
+
 }

simple_sns/src/main/java/com/example/sns/repository/LikeEntityRepository.java

@@ -4,12 +4,20 @@ import com.example.sns.model.entity.LikeEntity;
 import com.example.sns.model.entity.PostEntity;
 import com.example.sns.model.entity.UserEntity;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
+import java.util.List;
 import java.util.Optional;
 
 @Repository
 public interface LikeEntityRepository extends JpaRepository<LikeEntity, Integer> {
 
     Optional<LikeEntity> findByUserAndPost(UserEntity user, PostEntity post);
+
+    @Query(value = "SELECT COUNT(*) FROM LikeEntity entity WHERE entity.post =:post")
+    Integer countByPost(@Param("post") PostEntity post);
+
+    List<LikeEntity> findAllByPost(PostEntity post);
 }

simple_sns/src/main/java/com/example/sns/service/PostService.java

@@ -141,4 +141,17 @@ public class PostService {
         // save like
         likeEntityRepository.save(LikeEntity.of(userEntity, postEntity));
     }
+
+    public int likeCount(Integer postId) {
+        PostEntity postEntity = postEntityRepository.findById(postId)
+                .orElseThrow(
+                        () -> new SnsApplicationException(
+                                POST_NOT_FOUND,
+                                String.format("%s not founded", postId)
+                        )
+                );
+
+        // count like
+        return likeEntityRepository.countByPost(postEntity);
+    }
 }