feat: add result change log entities

backend/src/main/java/com/openisle/dto/PostChangeLogDto.java

@@ -11,6 +11,7 @@ import java.time.LocalDateTime;
 public class PostChangeLogDto {
     private Long id;
     private String username;
+    private String userAvatar;
     private PostChangeType type;
     private LocalDateTime time;
     private String oldTitle;

backend/src/main/java/com/openisle/mapper/PostChangeLogMapper.java

@@ -9,7 +9,10 @@ public class PostChangeLogMapper {
     public PostChangeLogDto toDto(PostChangeLog log) {
         PostChangeLogDto dto = new PostChangeLogDto();
         dto.setId(log.getId());
-        dto.setUsername(log.getUser().getUsername());
+        if (log.getUser() != null) {
+            dto.setUsername(log.getUser().getUsername());
+            dto.setUserAvatar(log.getUser().getAvatar());
+        }
         dto.setType(log.getType());
         dto.setTime(log.getCreatedAt());
         if (log instanceof PostTitleChangeLog t) {

backend/src/main/java/com/openisle/model/PostChangeLog.java

@@ -23,7 +23,7 @@ public abstract class PostChangeLog {
     @JoinColumn(name = "post_id")
     private Post post;
 
-    @ManyToOne(fetch = FetchType.LAZY, optional = false)
+    @ManyToOne(fetch = FetchType.LAZY, optional = true)
     @JoinColumn(name = "user_id")
     private User user;
 

backend/src/main/java/com/openisle/model/PostChangeType.java

@@ -7,5 +7,7 @@ public enum PostChangeType {
     TAG,
     CLOSED,
     PINNED,
-    FEATURED
+    FEATURED,
+    VOTE_RESULT,
+    LOTTERY_RESULT
 }

backend/src/main/java/com/openisle/model/PostLotteryResultChangeLog.java

@@ -0,0 +1,16 @@
+package com.openisle.model;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Table;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Getter
+@Setter
+@NoArgsConstructor
+@Entity
+@Table(name = "post_lottery_result_change_logs")
+public class PostLotteryResultChangeLog extends PostChangeLog {
+}
+

backend/src/main/java/com/openisle/model/PostVoteResultChangeLog.java

@@ -0,0 +1,16 @@
+package com.openisle.model;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Table;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Getter
+@Setter
+@NoArgsConstructor
+@Entity
+@Table(name = "post_vote_result_change_logs")
+public class PostVoteResultChangeLog extends PostChangeLog {
+}
+

backend/src/main/java/com/openisle/service/PostChangeLogService.java

@@ -86,6 +86,20 @@ public class PostChangeLogService {
         logRepository.save(log);
     }
 
+    public void recordVoteResult(Post post) {
+        PostVoteResultChangeLog log = new PostVoteResultChangeLog();
+        log.setPost(post);
+        log.setType(PostChangeType.VOTE_RESULT);
+        logRepository.save(log);
+    }
+
+    public void recordLotteryResult(Post post) {
+        PostLotteryResultChangeLog log = new PostLotteryResultChangeLog();
+        log.setPost(post);
+        log.setType(PostChangeType.LOTTERY_RESULT);
+        logRepository.save(log);
+    }
+
     public List<PostChangeLog> listLogs(Long postId) {
         Post post = postRepository.findById(postId)
                 .orElseThrow(() -> new com.openisle.exception.NotFoundException("Post not found"));