Fix medium db mapper

src/videoag_common/objects/medium.py

@@ -74,9 +74,10 @@ class SourceMedium(DeletableApiObject, Base):
             data_notes="Only calculated once this is sorted"
         )
     )
-    metadata: Mapped[JsonTypes] = api_mapped(
+    # metadata is reserved
+    file_metadata: Mapped[JsonTypes] = api_mapped(
         mapped_column(sql.JSON, nullable=True),
-        ApiDataField(
+        ApiJsonField(
             include_in_data=True,
             # See source file sorter for contents
             data_notes="Only calculated once this is sorted. There are no guarantees regarding the content"
@@ -195,8 +196,8 @@ class TargetMedium(DeletableApiObject, Base):
         return options
 
 
-class FileTargetMedium(TargetMedium):
-    file_path: Mapped[str] = mapped_column(String(collation=STRING_COLLATION), nullable=True, index=True)  # TODO move?
+class FileMedium(ApiObject):
+    file_path: Mapped[str] = mapped_column(String(collation=STRING_COLLATION), nullable=True, use_existing_column=True, index=True)  # TODO move?
     
     @api_include_in_data(
         type_id="string",
@@ -212,81 +213,80 @@ class FileTargetMedium(TargetMedium):
         return f"{self.process_target_id}.{self.id}"
 
 
-class SingleAudioContainingMedium(TargetMedium):
+class SingleAudioContainingMedium(ApiObject):
     
     audio_sample_rate: Mapped[int] = api_mapped(
-        mapped_column(nullable=True),
+        mapped_column(nullable=True, use_existing_column=True),
         ApiIntegerField(
             include_in_data=True,
-            help="In Hz"
+            data_notes="In Hz"
         )
     )
     audio_channel_count: Mapped[int] = api_mapped(
-        mapped_column(nullable=True),
+        mapped_column(nullable=True, use_existing_column=True),
         ApiIntegerField(
             include_in_data=True
         )
     )
 
 
-class SingleVideoContainingMedium(TargetMedium):
+class SingleVideoContainingMedium(ApiObject):
     
     video_vertical_resolution: Mapped[int] = api_mapped(
-        mapped_column(nullable=True),
+        mapped_column(nullable=True, use_existing_column=True),
         ApiIntegerField(
             include_in_data=True
         )
     )
     video_horizontal_resolution: Mapped[int] = api_mapped(
-        mapped_column(nullable=True),
+        mapped_column(nullable=True, use_existing_column=True),
         ApiIntegerField(
             include_in_data=True
         )
     )
     video_frame_rate_numerator: Mapped[int] = api_mapped(
-        mapped_column(nullable=True),
+        mapped_column(nullable=True, use_existing_column=True),
         ApiIntegerField(
             include_in_data=True
         )
     )
     video_frame_rate_denominator: Mapped[int] = api_mapped(
-        mapped_column(nullable=True),
+        mapped_column(nullable=True, use_existing_column=True),
         ApiIntegerField(
             include_in_data=True
         )
     )
 
 
-class PlainVideoTargetMedium(FileTargetMedium, SingleVideoContainingMedium, SingleAudioContainingMedium):
+class PlainVideoTargetMedium(TargetMedium, FileMedium, SingleVideoContainingMedium, SingleAudioContainingMedium):
     __tablename__ = None  # Prevent our own base from adding a table name. This should be a single-table inheritance
     __mapper_args__ = {
         "polymorphic_identity": TargetMediumType.PLAIN_VIDEO
     }
-    
     duration_sec: Mapped[int] = api_mapped(
-        mapped_column(nullable=True),
+        mapped_column(nullable=True, use_existing_column=True),
         ApiIntegerField(
             include_in_data=True
         )
     )
+    
     # TODO check vars not null (except audio)
 
 
-class PlainAudioTargetMedium(FileTargetMedium, SingleAudioContainingMedium):
+class PlainAudioTargetMedium(TargetMedium, FileMedium, SingleAudioContainingMedium):
     __tablename__ = None  # Prevent our own base from adding a table name. This should be a single-table inheritance
     __mapper_args__ = {
         "polymorphic_identity": TargetMediumType.PLAIN_AUDIO
     }
-    
     duration_sec: Mapped[int] = api_mapped(
-        mapped_column(nullable=True),
+        mapped_column(nullable=True, use_existing_column=True),
         ApiIntegerField(
             include_in_data=True
         )
     )
 
 
-class ThumbnailTargetMedium(FileTargetMedium):
+class ThumbnailTargetMedium(FileMedium):
     __tablename__ = None  # Prevent our own base from adding a table name. This should be a single-table inheritance
     __mapper_args__ = {
         "polymorphic_identity": TargetMediumType.THUMBNAIL