feat: Attachment 모델 추가 및 관련 기능 구현

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

blog/serializers.py

@@ -1,7 +1,33 @@
 # blog/serializers.py
 
+import os
+import re
 from rest_framework import serializers
-from .models import Post, Comment, Tag
+from .models import Post, Comment, Tag, Attachment
+
+
+def get_unique_filename(original_name, existing_names):
+    """
+    중복 파일명이 있으면 (2), (3) 등의 번호를 추가하여 고유한 파일명 반환
+    """
+    if original_name not in existing_names:
+        return original_name
+
+    name, ext = os.path.splitext(original_name)
+    match = re.match(r'^(.+)\((\d+)\)$', name)
+    if match:
+        base_name = match.group(1)
+        start_num = int(match.group(2)) + 1
+    else:
+        base_name = name
+        start_num = 2
+
+    counter = start_num
+    while True:
+        new_name = f"{base_name}({counter}){ext}"
+        if new_name not in existing_names:
+            return new_name
+        counter += 1
 
 
 class TagSerializer(serializers.ModelSerializer):
@@ -45,6 +71,21 @@ class CommentSerializer(serializers.ModelSerializer):
         return 0
 
 
+class AttachmentSerializer(serializers.ModelSerializer):
+    """첨부파일 시리얼라이저"""
+    file_url = serializers.SerializerMethodField()
+
+    class Meta:
+        model = Attachment
+        fields = ['id', 'file', 'file_url', 'original_name', 'file_size', 'uploaded_at']
+        read_only_fields = ['original_name', 'file_size', 'uploaded_at', 'file_url']
+
+    def get_file_url(self, obj):
+        if obj.file:
+            return obj.file.url
+        return None
+
+
 class PostSerializer(serializers.ModelSerializer):
     comment_count = serializers.SerializerMethodField()
     tags = TagSerializer(many=True, read_only=True)
@@ -53,6 +94,12 @@ class PostSerializer(serializers.ModelSerializer):
         write_only=True,
         required=False
     )
+    attachments = AttachmentSerializer(many=True, read_only=True)
+    attachment_ids = serializers.ListField(
+        child=serializers.IntegerField(),
+        write_only=True,
+        required=False
+    )  # 임시 업로드된 파일 ID 목록
 
     class Meta:
         model = Post
@@ -60,7 +107,8 @@ class PostSerializer(serializers.ModelSerializer):
             'id', 'title', 'content',
             'author_id', 'author_name',
             'created_at', 'updated_at',
-            'comment_count', 'tags', 'tag_names'
+            'comment_count', 'tags', 'tag_names',
+            'attachments', 'attachment_ids'
         ]
         read_only_fields = ['author_id', 'author_name', 'created_at', 'updated_at']
 
@@ -69,17 +117,22 @@ class PostSerializer(serializers.ModelSerializer):
 
     def create(self, validated_data):
         tag_names = validated_data.pop('tag_names', [])
+        attachment_ids = validated_data.pop('attachment_ids', [])
         post = Post.objects.create(**validated_data)
         self._set_tags(post, tag_names)
+        self._link_attachments(post, attachment_ids)
         return post
 
     def update(self, instance, validated_data):
         tag_names = validated_data.pop('tag_names', None)
+        attachment_ids = validated_data.pop('attachment_ids', None)
         for attr, value in validated_data.items():
             setattr(instance, attr, value)
         instance.save()
         if tag_names is not None:
             self._set_tags(instance, tag_names)
+        if attachment_ids is not None:
+            self._link_attachments(instance, attachment_ids)
         return instance
 
     def _set_tags(self, post, tag_names):
@@ -92,19 +145,54 @@ class PostSerializer(serializers.ModelSerializer):
                 tags.append(tag)
         post.tags.set(tags)
 
+    def _link_attachments(self, post, attachment_ids):
+        """임시 업로드된 첨부파일을 게시글에 연결 (중복 파일명 자동 번호 추가)"""
+        if not attachment_ids:
+            return
+
+        # 게시글의 기존 첨부파일명 목록
+        existing_names = set(post.attachments.values_list('original_name', flat=True))
+
+        # 임시 파일들을 가져와서 중복 체크 후 연결
+        temp_attachments = Attachment.objects.filter(
+            id__in=attachment_ids,
+            post__isnull=True
+        )
+
+        for attachment in temp_attachments:
+            unique_name = get_unique_filename(attachment.original_name, existing_names)
+            attachment.original_name = unique_name
+            attachment.post = post
+            attachment.save()
+            existing_names.add(unique_name)
+
 
 class PostListSerializer(serializers.ModelSerializer):
     """목록 조회용 간소화된 시리얼라이저"""
     comment_count = serializers.SerializerMethodField()
     tags = TagSerializer(many=True, read_only=True)
+    thumbnail = serializers.SerializerMethodField()
 
     class Meta:
         model = Post
         fields = [
             'id', 'title',
             'author_name', 'created_at', 'updated_at',
-            'comment_count', 'tags'
+            'comment_count', 'tags', 'thumbnail'
         ]
 
     def get_comment_count(self, obj):
         return obj.comments.count()
+
+    def get_thumbnail(self, obj):
+        """첫 번째 이미지 파일을 섬네일로 반환"""
+        image_extensions = ['.jpg', '.jpeg', '.png', '.gif', '.webp']
+        for attachment in obj.attachments.all():
+            original_name = attachment.original_name.lower()
+            if any(original_name.endswith(ext) for ext in image_extensions):
+                return {
+                    'id': attachment.id,
+                    'file_url': attachment.file.url if attachment.file else None,
+                    'original_name': attachment.original_name
+                }
+        return None