From 8ef89ecc850c8932d28f2bef59a6a5e2a3f89cc5 Mon Sep 17 00:00:00 2001
From: Colin Goutte <cgte@bk.ru>
Date: Sun, 27 Aug 2023 20:06:25 +0200
Subject: [PATCH] GREEN: Had to fiddle a bit with schemas and typing

---
 dev.py             | 20 +++++++++++++++++---
 schemas.py         |  9 +++++++++
 utests/test_api.py |  6 ++++--
 3 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/dev.py b/dev.py
index d080976..a351a75 100644
--- a/dev.py
+++ b/dev.py
@@ -118,8 +118,9 @@ async def list_movie(
     db: Session = Depends(get_db),
     pagenum: int | None = None,
     pagesize: int | None = None,
-) -> schemas.MovieObjectsOut:
+) -> schemas.PaginatedMovies | schemas.MovieObjectsOut:
     paginate_params = {}
+    paginate_data = {}
 
     pagination_params = {"pagenum": pagenum, "pagesize": pagesize}
     if any(v for v in pagination_params.values() if v is not None):
@@ -127,13 +128,26 @@ async def list_movie(
         if missing:
             raise HTTPException(status_code=404, detail=f"Missing {missing}")
 
-        paginate_params = dict(offset=(pagenum - 1) * pagesize, limit=pagesize)
+        # Here we do a "x + 1 - 1 = x" trick to check if there will be more pages
+        # eg we want from 10 to 15, we ask for 10 to 16, if we have *stricly* more
+        # than 5 element we can now that there will be one more page
+        paginate_params = dict(offset=(pagenum - 1) * pagesize, limit=pagesize + 1)
 
     movies = crud.get_all_movies(db, **paginate_params)
 
+    if paginate_params:
+        has_more_content = movies.count() > pagesize
+        paginate_data = {
+            "next_page": pagenum + 1 if has_more_content else None,
+            "previous_page": pagenum - 1 if pagenum > 1 else None,
+        }
+
+        movies = movies.limit(pagesize)
+
     count = movies.count()
 
-    return {"movies": movies, "count": count}
+    payload = {"movies": movies, "count": count}
+    return {**payload, **paginate_data}
 
 
 if __name__ == "__main__":
diff --git a/schemas.py b/schemas.py
index eb5da75..6e7e22a 100644
--- a/schemas.py
+++ b/schemas.py
@@ -16,6 +16,15 @@ class MovieObject(MoviePayload):
     id: int | str
 
 
+class Paginated(BaseModel):
+    next_page: str | int | None
+    previous_page: str | int | None
+
+
 class MovieObjectsOut(BaseModel):
     movies: list[MovieObject]
     count: int
+
+
+class PaginatedMovies(MovieObjectsOut, Paginated):
+    pass
diff --git a/utests/test_api.py b/utests/test_api.py
index 0d5aa0e..850791c 100644
--- a/utests/test_api.py
+++ b/utests/test_api.py
@@ -175,12 +175,14 @@ class BaseCrud(unittest.TestCase):
         current_movies = client.get(
             f"/movies/?pagenum={pagenum}&pagesize={pagesize}"
         ).json()
-        assert current_movies["previous_page"] is None
+        assert current_movies.get("previous_page") is None
+        assert current_movies["next_page"]
 
         current_movies = client.get(
             f"/movies/?pagenum={pagenum + 1 }&pagesize={pagesize}"
         ).json()
-        assert current_movies["next_page"] is None
+        assert current_movies.get("next_page") is None
+        assert current_movies["previous_page"]
 
         # test last page has no next