#14 simple blog : use builder

simpleblog/src/main/java/com/example/simpleblog/controller/ExceptionController.java

@@ -17,7 +17,10 @@ public class ExceptionController {
     public ErrorResponse invalidRequestHandler(MethodArgumentNotValidException e) {
 
 //        if (e.hasErrors()) {
-            ErrorResponse response = new ErrorResponse("400", "잘못된 요청입니다.");
+            ErrorResponse response = ErrorResponse.builder()
+                    .code("400")
+                    .message("잘못된 요청입니다.")
+                    .build();
 
             e.getFieldErrors().forEach(fieldError -> {
                 response.addValidation(fieldError.getField(), fieldError.getDefaultMessage());

simpleblog/src/main/java/com/example/simpleblog/controller/PostController.java

@@ -18,8 +18,7 @@ public class PostController {
     private final PostService postService;
 
     @PostMapping("/posts")
-    public PostCreate post(@RequestBody @Valid PostCreate request) {
+    public void post(@RequestBody @Valid PostCreate request) {
         postService.write(request);
-        return request;
     }
 }

simpleblog/src/main/java/com/example/simpleblog/domain/Post.java

@@ -1,6 +1,7 @@
 package com.example.simpleblog.domain;
 
 import lombok.AccessLevel;
+import lombok.Builder;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
 
@@ -20,6 +21,7 @@ public class Post {
     @Lob
     private String content;
 
+    @Builder
     public Post(String title, String content) {
         this.title = title;
         this.content = content;

simpleblog/src/main/java/com/example/simpleblog/request/PostCreate.java

@@ -1,17 +1,28 @@
 package com.example.simpleblog.request;
 
-import lombok.AllArgsConstructor;
+import lombok.Builder;
 import lombok.Data;
 
 import javax.validation.constraints.NotBlank;
 
 @Data
-@AllArgsConstructor
 public class PostCreate {
 
     @NotBlank(message = "제목을 입력해주세요.")
-    private String title;
+    private final String title;
 
     @NotBlank(message = "내용을 입력해주세요.")
-    private String content;
+    private final String content;
+
+    /**
+     * Builder
+     * - 가독성
+     * - 필요한 값만 받아서 생성 가능
+     * - 객체의 불변성
+     */
+    @Builder
+    public PostCreate(String title, String content) {
+        this.title = title;
+        this.content = content;
+    }
 }

simpleblog/src/main/java/com/example/simpleblog/response/ErrorResponse.java

@@ -1,7 +1,7 @@
 package com.example.simpleblog.response;
 
+import lombok.Builder;
 import lombok.Getter;
-import lombok.RequiredArgsConstructor;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -16,7 +16,6 @@ import java.util.Map;
  * }
  */
 @Getter
-@RequiredArgsConstructor
 public class ErrorResponse {
 
     private final String code;
@@ -24,6 +23,12 @@ public class ErrorResponse {
 
     private final Map<String, String> validation = new HashMap<>();
 
+    @Builder
+    public ErrorResponse(String code, String message) {
+        this.code = code;
+        this.message = message;
+    }
+
     public void addValidation(String field, String errorMessage) {
         this.validation.put(field, errorMessage);
     }

simpleblog/src/main/java/com/example/simpleblog/service/PostService.java

@@ -16,7 +16,11 @@ public class PostService {
 
     public void write(PostCreate postCreate) {
 
-        Post post = new Post(postCreate.getTitle(), postCreate.getContent());
+        Post post = Post.builder()
+                .title(postCreate.getTitle())
+                .content(postCreate.getContent())
+                .build();
+
         postRepository.save(post);
     }
 }

simpleblog/src/test/java/com/example/simpleblog/controller/PostControllerTest.java

@@ -10,10 +10,10 @@ import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.http.MediaType;
 import org.springframework.test.web.servlet.MockMvc;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.springframework.http.MediaType.APPLICATION_JSON;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
 import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
@@ -39,28 +39,37 @@ class PostControllerTest {
     @Test
     @DisplayName("/posts 요청시 저장된 값을 출력한다.")
     void posts() throws Exception {
-        PostCreate request = new PostCreate("글 제목입니다.", "글 내용입니다.");
+        // given
+        PostCreate request = PostCreate.builder()
+                .title("글 제목입니다.")
+                .content("글 내용입니다.")
+                .build();
+
         String jsonString = objectMapper.writeValueAsString(request);
 
         // expected
         mockMvc.perform(post("/posts")
-                        .contentType(MediaType.APPLICATION_JSON)
+                        .contentType(APPLICATION_JSON)
                         .content(jsonString)
                 )
                 .andExpect(status().isOk())
-                .andExpect(content().json(jsonString))
+                .andExpect(content().string(""))
                 .andDo(print());
     }
 
     @Test
     @DisplayName("/posts 요청시 title값은 필수다.")
     void posts_validation() throws Exception {
-        PostCreate request = new PostCreate("", "글 내용입니다.");
+        // given
+        PostCreate request = PostCreate.builder()
+                .content("글 내용입니다.")
+                .build();
+
         String jsonString = objectMapper.writeValueAsString(request);
 
         // expected
         mockMvc.perform(post("/posts")
-                        .contentType(MediaType.APPLICATION_JSON)
+                        .contentType(APPLICATION_JSON)
                         .content(jsonString)
                 )
                 .andExpect(status().isBadRequest())
@@ -74,12 +83,17 @@ class PostControllerTest {
     @Test
     @DisplayName("/posts 요청시 DB에 값이 저장된다.")
     void save_post() throws Exception {
-        PostCreate request = new PostCreate("글 제목입니다.", "글 내용입니다.");
+        // given
+        PostCreate request = PostCreate.builder()
+                .title("글 제목입니다.")
+                .content("글 내용입니다.")
+                .build();
+
         String jsonString = objectMapper.writeValueAsString(request);
 
         // when
         mockMvc.perform(post("/posts")
-                        .contentType(MediaType.APPLICATION_JSON)
+                        .contentType(APPLICATION_JSON)
                         .content(jsonString)
                 )
                 .andExpect(status().isOk())