Local File Source

LOCAL_FILE source type

Real backend support for cataloguing cards from a local directory on the server's disk, as a Source type alongside Google Drive. LocalFile in cardpicker/sources/source_types.py was previously a stub (only get_identifier() implemented) despite the DB schema/enum and Source.identifier's own field comment already anticipating it.

How it works

• Source.identifier is a root directory path on disk. Folders/images are discovered by walking the filesystem (os.scandir) instead of an API call; image dimensions (needed for the DPI calculation Drive gets for free from imageMediaMetadata.height) are read locally via Pillow. Symlinked files and directories are never followed/traversed during indexing — deliberately, to avoid both symlink cycles and a symlink escaping the source's root directory.
• Since the frontend only loads images by URL, a get_local_file_image view (cardpicker/views.py, routed at 2/localFileImage/) serves image bytes back out. Treated as a real security surface: the identifier query param is untrusted input, so the view (a) looks up a real Card row scoped to source__source_type == LOCAL_FILE, then (b) independently re-resolves and validates the path stays inside that source's currently configured root via resolve_within_root (cardpicker/sources/api.py) — covering ../ traversal and symlink escapes, and re-checked at serve time (not just trusted from indexing) in case a source's root was reconfigured after its images were catalogued.
• LOCAL_FILE_SOURCE_BASE_URL (Django setting, defaults to http://localhost:8000) builds the thumbnail URLs returned by get_small_thumbnail_url/get_medium_thumbnail_url, since those are static methods with no request object to introspect the server's own base URL.
• update_database.py's indexing pipeline needed no changes — it already dispatches generically over SourceType. Re-scanning a single source works via update_database --drive <key> (flag name is a naming leftover from Drive-only days, works for any source type — help text updated to say so) or a new rescan_sources admin action on Source.

Key files

• cardpicker/sources/source_types.py (LocalFile)
• cardpicker/sources/api.py (resolve_within_root)
• cardpicker/views.py (get_local_file_image)
• cardpicker/tests/test_local_file_source.py

Status

17 new tests, fully self-contained against real tmp_path directories/ files — no network or credentials needed, unlike GoogleDrive's own tests (which hit a real external Drive folder and are part of the documented "2 Google Drive creds" known CI failures; see Infrastructure).