save follow

src/main/java/io/spring/api/ProfileApi.java

@@ -3,12 +3,15 @@ package io.spring.api;
 import io.spring.api.exception.ResourceNotFoundException;
 import io.spring.application.profile.ProfileData;
 import io.spring.application.profile.ProfileQueryService;
+import io.spring.core.user.FollowRelation;
 import io.spring.core.user.User;
+import io.spring.core.user.UserRepository;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
@@ -18,10 +21,12 @@ import java.util.HashMap;
 @RequestMapping(path = "profiles/{username}")
 public class ProfileApi {
     private ProfileQueryService profileQueryService;
+    private UserRepository userRepository;
 
     @Autowired
-    public ProfileApi(ProfileQueryService profileQueryService) {
+    public ProfileApi(ProfileQueryService profileQueryService, UserRepository userRepository) {
         this.profileQueryService = profileQueryService;
+        this.userRepository = userRepository;
     }
 
     @GetMapping
@@ -32,6 +37,16 @@ public class ProfileApi {
             .orElseThrow(ResourceNotFoundException::new);
     }
 
+    @PostMapping(path = "follow")
+    public ResponseEntity follow(@PathVariable("username") String username,
+                                 @AuthenticationPrincipal User user) {
+        return userRepository.findByUsername(username).map(target -> {
+            FollowRelation followRelation = new FollowRelation(user.getId(), target.getId());
+            userRepository.saveRelation(followRelation);
+            return profileResponse(profileQueryService.findByUsername(username, user).get());
+        }).orElseThrow(ResourceNotFoundException::new);
+    }
+
     private ResponseEntity profileResponse(ProfileData profile) {
         return ResponseEntity.ok(new HashMap<String, Object>() {{
             put("profile", profile);

src/main/java/io/spring/core/user/FollowRelation.java

@@ -0,0 +1,17 @@
+package io.spring.core.user;
+
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@NoArgsConstructor
+public class FollowRelation {
+    private String userId;
+    private String targetId;
+
+    public FollowRelation(String userId, String targetId) {
+
+        this.userId = userId;
+        this.targetId = targetId;
+    }
+}

src/main/java/io/spring/core/user/UserRepository.java

@@ -13,4 +13,8 @@ public interface UserRepository {
     Optional<User> findByUsername(String username);
 
     Optional<User> findByEmail(String email);
+
+    void saveRelation(FollowRelation followRelation);
+
+    Optional<FollowRelation> findRelation(String userId, String targetId);
 }

src/main/java/io/spring/infrastructure/user/MyBatisUserRepository.java

@@ -1,5 +1,6 @@
 package io.spring.infrastructure.user;
 
+import io.spring.core.user.FollowRelation;
 import io.spring.core.user.User;
 import io.spring.core.user.UserRepository;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -39,4 +40,14 @@ public class MyBatisUserRepository implements UserRepository {
     public Optional<User> findByEmail(String email) {
         return Optional.ofNullable(userMapper.findByEmail(email));
     }
+
+    @Override
+    public void saveRelation(FollowRelation followRelation) {
+        userMapper.saveRelation(followRelation);
+    }
+
+    @Override
+    public Optional<FollowRelation> findRelation(String userId, String targetId) {
+        return Optional.ofNullable(userMapper.findRelation(userId, targetId));
+    }
 }

src/main/java/io/spring/infrastructure/user/UserMapper.java

@@ -1,5 +1,6 @@
 package io.spring.infrastructure.user;
 
+import io.spring.core.user.FollowRelation;
 import io.spring.core.user.User;
 import org.apache.ibatis.annotations.Mapper;
 import org.apache.ibatis.annotations.Param;
@@ -16,4 +17,8 @@ public interface UserMapper {
     User findById(@Param("id") String id);
 
     void update(@Param("user") User user);
+
+    FollowRelation findRelation(@Param("userId") String userId, @Param("targetId") String targetId);
+
+    void saveRelation(@Param("followRelation") FollowRelation followRelation);
 }