졸업작품 랜덤하게 노출

app/grad_2025/schemas.py

@@ -20,6 +20,7 @@ def from_grad_2025(cls, grad_2025: Grad2025):
 
 class Grad2025Cursor(APISchema):
     id: int
+    seed: str | None = None
 
     def encode(self) -> str:
         payload = self.model_dump_json().encode()

app/grad_2025/service.py

@@ -1,3 +1,5 @@
+import uuid
+
 from app.category.enums import Category
 from app.common.schemas import Page
 from app.posts.repository import PostRepository
@@ -28,17 +30,19 @@ async def search_posts(
         categories: list[Category] | None = None,
         univ_majors: list[str] | None = None,
     ) -> Page[PostCompactRead]:
-        cursor_id = cursor.id if cursor else None
+        seed = cursor.seed if cursor and cursor.seed else str(uuid.uuid4())
+
         posts = await self.post_repository.find_grad_2025_posts(
-            cursor=cursor_id,
+            seed=seed,
+            cursor=cursor,
             limit=limit + 1,
             categories=categories,
             univ_majors=univ_majors,
         )
         has_next = len(posts) > limit
         if has_next:
             posts = posts[:-1]
-            next_cursor = Grad2025Cursor(id=posts[-1].id).encode()
+            next_cursor = Grad2025Cursor(id=posts[-1].id, seed=seed).encode()
         else:
             next_cursor = None
         compact_posts = [PostCompactRead.from_post(post) for post in posts]

app/posts/repository.py

@@ -8,6 +8,7 @@
 from app.common.schemas import FeedCursor
 from app.database.deps import SessionDep
 from app.grad_2025.models import Grad2025
+from app.grad_2025.schemas import Grad2025Cursor
 from app.users.models import User
 from app.utils.dependency import dependency
 
@@ -296,12 +297,17 @@ async def find_univ_major_by_post_id(self, *, post_id: int) -> Grad2025 | None:
     async def find_grad_2025_posts(
         self,
         *,
-        cursor: int | None,
+        seed: str,
+        cursor: Grad2025Cursor | None,
         limit: int,
         categories: list[Category] | None = None,
         univ_majors: list[str] | None = None,
     ) -> list[Post]:
-        """post_grad_2025_table에 존재하는 Post만 조회합니다."""
+        """post_grad_2025_table에 존재하는 Post만 조회합니다. 시드 기반 랜덤 정렬."""
+        random_order = func.md5(func.concat(seed, Post.id.cast(String))).label(
+            "random_order"
+        )
+
         stmt = (
             select(Post)
             .options(
@@ -310,19 +316,16 @@ async def find_grad_2025_posts(
             )
             .join(post_grad_2025_table, Post.id == post_grad_2025_table.c.post_id)
             .where(Post.deleted_at.is_(None))
-            .order_by(Post.created_at.desc(), Post.id.desc())
+            .order_by(random_order, Post.id.desc())
             .limit(limit)
         )
 
         if cursor is not None:
-            # 커서 id의 created_at을 가져와서 그 이전 것들만 조회
-            cursor_created_at = (
-                select(Post.created_at).where(Post.id == cursor).scalar_subquery()
-            )
+            current_random = func.md5(func.concat(seed, str(cursor.id)))
             stmt = stmt.where(
                 or_(
-                    Post.created_at < cursor_created_at,
-                    and_(Post.created_at == cursor_created_at, Post.id < cursor),
+                    random_order > current_random,
+                    and_(random_order == current_random, Post.id < cursor.id),
                 )
             )