Separate MediaThumbnail & *Cache tables

server/app.py

@@ -648,13 +648,14 @@ def show_thumb(thumbnail_id: int) -> ResponseReturnValue:
     if thumbnail is None:
         # do send only 404 (not default thumbnail) as invalid id was requested
         return make_response(f"Not found", 404)
+    thumb_cache = thumbnail.receive()
     # TODO do not load data from database until send_file requires that
     return send_file(
-        io.BytesIO(thumbnail.receive_data()),
-        mimetype=thumbnail.mime_type,
+        io.BytesIO(thumb_cache.access_data()),
+        mimetype=thumb_cache.mime_type,
         etag=True,
         as_attachment=False,
-        last_modified=thumbnail.last_downloaded,
+        last_modified=thumb_cache.last_downloaded,
         max_age=24 * 60 * 60,
     )
 

server/entertainment_decider/models/__init__.py

@@ -10,6 +10,7 @@ from .entities import (
     MediaCollectionLink,
     MediaElement,
     MediaThumbnail,
+    MediaThumbnailCache,
     MediaUriMapping,
     Tag,
     Tagable,

server/entertainment_decider/models/entities.py

@@ -572,58 +572,59 @@ class MediaThumbnail(db.Entity):
         str,
         unique=True,
     )
-    last_downloaded: datetime = orm.Optional(
-        datetime,
-        default=None,
+
+    __cache_obj: MediaThumbnailCache = orm.Optional(
+        lambda: MediaThumbnailCache,
         nullable=True,
     )
+    elements: Set[MediaElement] = orm.Set(lambda: MediaElement)
+
+    @classmethod
+    def from_uri(cls, uri: str) -> MediaThumbnail:
+        return cls.get(uri=uri) or MediaThumbnail(uri=uri)
+
+    def receive(self) -> MediaThumbnailCache:
+        return self.__cache_obj or MediaThumbnailCache.download(self)
+
+
+class MediaThumbnailCache(db.Entity):
+    thumbnail: MediaThumbnail = orm.PrimaryKey(
+        lambda: MediaThumbnail,
+        auto=False,
+    )
+    last_downloaded: datetime = orm.Required(
+        datetime,
+    )
     last_accessed: datetime = orm.Optional(
         datetime,
-        default=None,
         nullable=True,
     )
-    mime_type: str = orm.Optional(
+    mime_type: str = orm.Required(
         str,
-        default="",
     )
-    data: bytes = orm.Optional(
+    _data: bytes = orm.Required(
         bytes,
-        default=None,
-        nullable=True,
+        column="data",
         lazy=True,  # do not always preload huge image data
     )
 
-    elements: Set[MediaElement] = orm.Set(lambda: MediaElement)
-
     @classmethod
-    def from_uri(cls, uri: str) -> MediaThumbnail:
-        return cls.get(uri=uri) or MediaThumbnail(uri=uri)
-
-    def access(self) -> None:
-        self.last_accessed = datetime.now()
-
-    def download(self) -> bool:
-        res = requests.get(url=self.uri, headers=THUMBNAIL_HEADERS)
+    def download(cls, thumbnail: MediaThumbnail) -> MediaThumbnailCache:
+        res = requests.get(url=thumbnail.uri, headers=THUMBNAIL_HEADERS)
         mime = magic.from_buffer(res.content, mime=True)
         if mime not in THUMBNAIL_ALLOWED_TYPES:
             raise Exception(f"Couldn't download thumbnail: {thumbnail.uri}")
-        self.mime_type = mime
-        self.data = res.content
-        self.last_downloaded = datetime.now()
-        return True
-
-    def prepare(self) -> bool:
-        if self.last_downloaded is not None:
-            return True
-        return self.download()
-
-    def access_data(self) -> None:
-        self.prepare()
-        self.access()
+        now = datetime.now()
+        return cls(
+            thumbnail=thumbnail,
+            last_downloaded=now,
+            mime_type=mime,
+            _data=res.content,
+        )
 
-    def receive_data(self) -> bytes:
-        self.access_data()
-        return self.data
+    def access_data(self) -> bytes:
+        self.last_accessed = datetime.now()
+        return self._data
 
 
 class MediaUriMapping(db.Entity):