Files
mule-image/backend/app/services/metadata.py
Claudio 576b0c236d feat(thumbs): proxy Nextcloud previews instead of duplicating the cache
mule-image was generating and storing three WebP sizes per photo in
/data/thumbs while Nextcloud already keeps its own previews for the
same source files. Frontend thumbnail requests now proxy NC's
/index.php/core/preview keyed by the photo's Nextcloud fileid,
authenticated with the owner's encrypted app password.

- new column photos.nextcloud_fileid (alembic 0018) plus an index
- get_preview_async + fetch_fileid helpers in nextcloud_dav.py
- thumb route proxies NC primary, falls back to /data/thumbs (legacy
  rows / NC unreachable) so a single-file revert restores the old path
- extract_metadata caches the fileid on first run for new photos
- generate_thumbnails now writes only medium since the vision worker
  still loads it from disk; small + large drop out of the worker path
- backend/scripts/backfill_nextcloud_fileid.py for one-shot population
  of existing rows: docker exec mulita-backend python -m scripts.backfill_nextcloud_fileid

X-Mule-Thumb-Source response header marks each request 'nextcloud' or
'disk' for observability while the rollout settles.
2026-05-11 11:34:58 +02:00

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"""
Metadata extraction service using ExifTool
"""
import json
import logging
import re
import asyncio
from datetime import datetime
from typing import Dict, Optional
import subprocess
from pathlib import Path
from celery import shared_task
from sqlalchemy import select
from app.database import AsyncSessionLocal
from app.models import Photo
from app.services.date_guess import has_date_warning
logger = logging.getLogger(__name__)
def parse_exif_datetime(date_str: str) -> Optional[datetime]:
"""Parse EXIF datetime string to Python datetime.
Returns a tz-naive datetime — the photos.taken_at column is
`timestamp without time zone`. Tz-aware inputs (e.g. SubSec
fields with `+02:00` or QuickTime UTC `Z`) are converted to UTC
and stripped. Cameras that wrote the all-zero placeholder
return None.
"""
if not date_str:
return None
s = str(date_str).strip()
# All-zero placeholder some cameras emit when the clock isn't set.
if s.startswith("0000:00:00") or s.startswith("0000-00-00"):
return None
formats = [
"%Y:%m:%d %H:%M:%S",
"%Y-%m-%d %H:%M:%S",
"%Y:%m:%d %H:%M:%S.%f",
"%Y-%m-%dT%H:%M:%S",
"%Y-%m-%dT%H:%M:%S.%f",
# Tz-aware variants: SubSecDateTimeOriginal often looks like
# "2023:11:30 14:30:45.123+02:00", QuickTime CreateDate as
# "2023:11:30 14:30:45Z" or with offsets.
"%Y:%m:%d %H:%M:%S%z",
"%Y:%m:%d %H:%M:%S.%f%z",
"%Y-%m-%dT%H:%M:%S%z",
"%Y-%m-%dT%H:%M:%S.%f%z",
]
for fmt in formats:
try:
dt = datetime.strptime(s, fmt)
except ValueError:
continue
if dt.tzinfo is not None:
from datetime import timezone
dt = dt.astimezone(timezone.utc).replace(tzinfo=None)
return dt
return None
_DMS_RE = re.compile(
r"""\s*
(?P<deg>-?\d+(?:\.\d+)?)\s*(?:deg|°|d)?\s*
(?:(?P<min>\d+(?:\.\d+)?)\s*[\'m]?\s*)?
(?:(?P<sec>\d+(?:\.\d+)?)\s*[\"”s]?\s*)?
(?P<ref>[NSEW])?\s*$""",
re.IGNORECASE | re.VERBOSE,
)
def _parse_coord(value, ref: str | None) -> float | None:
"""Coerce a single GPS coordinate from any form ExifTool may emit.
ExifTool's ``-j`` JSON output applies print conversion by default, so
coordinates can come back as:
* a number (``48.1278``) — happens for some sources / when ``-n`` is set
* a plain DMS string (``"48 deg 7' 39.96\\""``) — bare ``EXIF:GPSLatitude``
* a DMS-with-ref string (``"48 deg 7' 39.96\\" N"``) — ``Composite:GPSLatitude``
The optional ``ref`` argument lets the caller pass an explicit
``GPSLatitudeRef`` / ``GPSLongitudeRef`` ('N'/'S'/'E'/'W') when the
string itself doesn't carry one. Returns signed decimal degrees, or
``None`` if the value is unparseable.
"""
if value is None:
return None
# Numeric path — already decimal degrees, possibly already signed.
if isinstance(value, (int, float)):
out = float(value)
else:
m = _DMS_RE.match(str(value))
if not m:
return None
deg = float(m.group('deg'))
minutes = float(m.group('min') or 0)
seconds = float(m.group('sec') or 0)
out = abs(deg) + minutes / 60.0 + seconds / 3600.0
if deg < 0:
out = -out
embedded_ref = m.group('ref')
if embedded_ref:
ref = embedded_ref
if ref:
r = ref[0].upper()
if r in ('S', 'W'):
out = -abs(out)
elif r in ('N', 'E'):
out = abs(out)
return out
def extract_gps(exif_data: Dict) -> tuple:
"""Return (lat, lon) in signed decimal degrees, or (None, None).
With ``exiftool -G -j`` GPS values are keyed under their group.
``Composite:GPSLatitude`` / ``Composite:GPSLongitude`` carry the
hemisphere reference inline (``"48 deg 7' 39.96\\" N"``) while the bare
``EXIF:GPSLatitude`` / ``EXIF:GPSLongitude`` need the separate
``EXIF:GPSLatitudeRef`` / ``EXIF:GPSLongitudeRef`` to know the sign.
Pre-fix this function read the *unprefixed* keys ``GPSLatitude`` /
``GPSLongitude`` (which never exist in ``-G`` output) AND assumed
they were already floats — so it silently dropped every photo's GPS.
"""
lat = _parse_coord(exif_data.get('Composite:GPSLatitude'), None)
lon = _parse_coord(exif_data.get('Composite:GPSLongitude'), None)
if lat is None or lon is None:
lat = _parse_coord(
exif_data.get('EXIF:GPSLatitude'),
exif_data.get('EXIF:GPSLatitudeRef'),
)
lon = _parse_coord(
exif_data.get('EXIF:GPSLongitude'),
exif_data.get('EXIF:GPSLongitudeRef'),
)
if lat is None or lon is None:
return None, None
if not (-90 <= lat <= 90 and -180 <= lon <= 180):
return None, None
# Some cameras emit (0, 0) when they have no GPS lock — treat as missing
if lat == 0 and lon == 0:
return None, None
return lat, lon
def extract_key_metadata(exif_data: Dict) -> Dict:
"""Extract key metadata fields for FTS indexing"""
key_fields = []
# Camera information
if 'EXIF:Make' in exif_data:
key_fields.append(exif_data['EXIF:Make'])
if 'EXIF:Model' in exif_data:
key_fields.append(exif_data['EXIF:Model'])
if 'EXIF:LensModel' in exif_data:
key_fields.append(exif_data['EXIF:LensModel'])
# Location information
lat, lon = extract_gps(exif_data)
if lat is not None and lon is not None:
key_fields.append(f"GPS: {lat}, {lon}")
# IPTC/XMP keywords
keywords = exif_data.get('IPTC:Keywords') or exif_data.get('XMP:Subject')
if keywords:
if isinstance(keywords, list):
key_fields.extend(keywords)
else:
key_fields.append(keywords)
# Copyright and creator
if 'EXIF:Copyright' in exif_data:
key_fields.append(exif_data['EXIF:Copyright'])
if 'XMP:Creator' in exif_data:
key_fields.append(exif_data['XMP:Creator'])
if 'EXIF:Artist' in exif_data:
key_fields.append(exif_data['EXIF:Artist'])
return {
'exif_text': ' '.join(str(f) for f in key_fields),
'camera_make': exif_data.get('EXIF:Make'),
'camera_model': exif_data.get('EXIF:Model'),
'lens_model': exif_data.get('EXIF:LensModel'),
'gps_latitude': lat,
'gps_longitude': lon,
}
@shared_task(name='extract_metadata')
def extract_metadata(photo_id: str):
"""Extract metadata from a photo using ExifTool"""
return asyncio.run(_extract_metadata_async(photo_id))
async def _extract_metadata_async(photo_id: str):
"""Async implementation of metadata extraction"""
async with AsyncSessionLocal() as session:
try:
# Get photo from database
result = await session.execute(
select(Photo).where(Photo.id == photo_id)
)
photo = result.scalar_one_or_none()
if not photo:
logger.error(f"Photo not found: {photo_id}")
return {'status': 'error', 'message': 'Photo not found'}
# Cache Nextcloud's numeric fileid on the row so the thumbnail
# handler can proxy /index.php/core/preview without doing a
# PROPFIND per request. PROPFIND blocks for ~50ms; tolerable
# because extract_metadata already does seconds of ExifTool
# work. Failures are silent — the thumb handler falls back
# to its on-disk path when the column is NULL.
if photo.nextcloud_fileid is None and photo.user_id:
from app.models.user import User
from app.services.nextcloud_dav import (
fetch_fileid, is_nextcloud_path,
)
if photo.filepath and is_nextcloud_path(photo.filepath):
owner = (
await session.execute(
select(User).where(User.id == photo.user_id)
)
).scalar_one_or_none()
if owner is not None and owner.nextcloud_app_password_enc:
try:
fid = fetch_fileid(owner, photo.filepath)
except Exception as e:
logger.warning(
"fileid lookup failed for %s: %s", photo_id, e
)
fid = None
if fid is not None:
photo.nextcloud_fileid = fid
# Check if file exists
if not Path(photo.filepath).exists():
logger.error(f"File not found: {photo.filepath}")
return {'status': 'error', 'message': 'File not found'}
# Run ExifTool to extract metadata
cmd = [
'exiftool',
'-j', # JSON output
'-G', # Group names
'-s', # Short output format
'-All', # All metadata
photo.filepath
]
try:
result = subprocess.run(
cmd,
capture_output=True,
text=True,
timeout=30,
stdin=subprocess.DEVNULL,
)
if result.returncode != 0:
logger.error(f"ExifTool error: {result.stderr}")
photo.processing_error = f"ExifTool: {result.stderr[:500]}"
await session.commit()
return {'status': 'error', 'message': result.stderr}
# Parse JSON output
metadata = json.loads(result.stdout)
if metadata and len(metadata) > 0:
exif_data = metadata[0]
# Store full metadata as JSON
photo.exif_json = json.dumps(exif_data)
# Extract taken_at date — but only if the user hasn't
# explicitly set it via the UI. Manual edits are the
# source of truth and must survive any rescan.
if photo.taken_at_source != 'manual':
# Trusted EXIF fields, in order of preference.
# SubSecDateTimeOriginal includes sub-second
# precision and often a tz offset, so it's the
# most accurate when present. ModifyDate is NOT
# in this list — it's set every time the file
# is re-saved (Lightroom export, EXIF strip,
# batch resize) and routinely overwrote correct
# capture dates with edit-time dates.
date_fields = [
'EXIF:SubSecDateTimeOriginal',
'EXIF:DateTimeOriginal',
'EXIF:CreateDate',
'QuickTime:MediaCreateDate',
'QuickTime:CreateDate',
]
new_taken_at = None
for field in date_fields:
if field in exif_data:
parsed = parse_exif_datetime(exif_data[field])
if parsed:
new_taken_at = parsed
photo.taken_at = parsed
photo.taken_at_source = 'exif'
break
# Fallback: if the file has no trusted EXIF date,
# try to extract one from the filename / folder
# path. The same date_guess module powers the
# has_date_warning flag — reusing it here means
# photos without EXIF (scanned prints, stripped
# JPEGs, re-saved exports) get a sensible date
# instead of falling back to filesystem mtime
# (which on Nextcloud-mounted files is just the
# upload time).
if new_taken_at is None:
from app.services.date_guess import guess_date_from_path
guess = guess_date_from_path(photo.filepath)
if guess is not None:
photo.taken_at = guess.date
photo.taken_at_source = 'path'
# Re-run the path-vs-date heuristic now that we know
# whether EXIF provided a real capture date. A true EXIF
# date that matches the folder clears the warning the
# scanner set during the filesystem-mtime pass.
photo.has_date_warning = has_date_warning(
photo.filepath, photo.taken_at
)
# Extract dimensions if not already set
if not photo.width:
photo.width = exif_data.get('EXIF:ImageWidth') or exif_data.get('File:ImageWidth')
if not photo.height:
photo.height = exif_data.get('EXIF:ImageHeight') or exif_data.get('File:ImageHeight')
# Extract GPS coordinates into first-class columns so the
# Map view can query them without parsing exif_json.
lat, lon = extract_gps(exif_data)
photo.latitude = lat
photo.longitude = lon
# Extract and store key metadata for search
key_metadata = extract_key_metadata(exif_data)
await session.commit()
logger.info(f"Metadata extracted for photo {photo_id}")
return {
'status': 'success',
'photo_id': photo_id,
'taken_at': photo.taken_at.isoformat() if photo.taken_at else None
}
except subprocess.TimeoutExpired:
logger.error(f"ExifTool timeout for {photo.filepath}")
photo.processing_error = 'ExifTool timeout'
await session.commit()
return {'status': 'error', 'message': 'ExifTool timeout'}
except json.JSONDecodeError as e:
logger.error(f"Failed to parse ExifTool output: {e}")
photo.processing_error = f"Invalid ExifTool output: {e}"
await session.commit()
return {'status': 'error', 'message': 'Invalid ExifTool output'}
except Exception as e:
logger.error(f"Error extracting metadata for {photo_id}: {e}")
return {'status': 'error', 'message': str(e)}
@shared_task(name='backfill_taken_at')
def backfill_taken_at():
"""Re-enqueue extract_metadata for every non-manual photo.
Used after fixing the date-extraction logic (removing ModifyDate
fallback, adding path-based fallback) to re-derive taken_at across
the whole library without touching photos the user has manually
corrected. Each enqueued task is fast (~90ms) and runs on the
default queue; ~21k photos finish in ~15 min on the existing
worker-light concurrency.
"""
return asyncio.run(_backfill_taken_at_async())
async def _backfill_taken_at_async():
from sqlalchemy import or_
async with AsyncSessionLocal() as session:
result = await session.execute(
select(Photo.id).where(
# NULL taken_at_source predates the column default and
# should still be re-extracted; only 'manual' is sacred.
or_(
Photo.taken_at_source != 'manual',
Photo.taken_at_source.is_(None),
),
Photo.is_discarded.is_(False),
)
)
photo_ids = [row[0] for row in result.all()]
for pid in photo_ids:
extract_metadata.delay(pid)
logger.info(f"backfill_taken_at: queued extract_metadata for {len(photo_ids)} photos")
return {'queued': len(photo_ids)}