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FabledCurator/alembic/versions/0022_source_per_artist_platform.py

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Python

"""source-collapse: one Source per (artist, platform) — consolidate junk per-post Sources
Revision ID: 0022
Revises: 0021
Create Date: 2026-05-26
Closes the operator-flagged 2026-05-26 issue where the filesystem importer
called _find_or_create_source(url=sd.post_url), creating one Source row per
imported post URL. Operator's Atole artist had 406 Source rows where there
should have been 1 (the /cw/Atole subscription Source).
Source represents a subscription feed (one per artist+platform — the
gallery-dl URL polled by the FC-3 downloader). Posts hang off it. The
filesystem importer was misusing Source as a per-post key.
Migration steps per (artist_id, platform) group with >1 Source:
1. Pick canonical — prefer a URL NOT matching '/posts/<id>$' (real
campaign URL like /cw/Atole); else min(id).
2. PRE-merge any Posts under non-canonical sources whose
external_post_id ALREADY exists under the canonical source. (Same
gallery-dl post imported via two different sidecar paths can plant
two Post rows with identical external_post_id under different
Sources for the same artist.) Repoint ImageProvenance +
ImageRecord.primary_post_id to the canonical-side Post, dedupe
ImageProvenance against alembic 0021's uq, then delete the
non-canonical-side Post. This MUST happen before step 3 — Postgres
fires uq_post_source_external_id row-by-row during the bulk UPDATE
and the merge-after-reparent ordering 500s on first collision
(operator-hit during v26.05.26.1 deploy, 2026-05-26).
3. Reparent remaining Posts onto canonical (no collisions possible now).
4. Reparent ImageProvenance.source_id off the non-canonical sources.
5. Delete the orphan Source rows.
6. If the canonical Source's URL still looks like a per-post URL (no
campaign URL existed among candidates), rewrite it to
'sidecar:<platform>:<artist_slug>' so the artist detail page shows
something readable.
"""
from typing import Sequence, Union
from alembic import op
from sqlalchemy import text
revision: str = "0022"
down_revision: Union[str, None] = "0021"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None
_POST_URL_RE = r"/posts/[^/]+$"
def upgrade() -> None:
conn = op.get_bind()
# Find (artist_id, platform) groups with > 1 Source row.
groups = conn.execute(text("""
SELECT artist_id, platform
FROM source
GROUP BY artist_id, platform
HAVING COUNT(*) > 1
""")).fetchall()
for artist_id, platform in groups:
rows = conn.execute(
text("""
SELECT id, url FROM source
WHERE artist_id = :a AND platform = :p
ORDER BY id ASC
"""),
{"a": artist_id, "p": platform},
).fetchall()
# Canonical: first row whose URL doesn't look like a per-post URL;
# else min(id).
canonical_id = None
for sid, url in rows:
if not _matches_post_url(url):
canonical_id = sid
break
if canonical_id is None:
canonical_id = rows[0][0]
other_ids = [sid for sid, _ in rows if sid != canonical_id]
if not other_ids:
continue
# STEP 2: PRE-merge ALL Posts with duplicate external_post_id
# across the entire (canonical + others) group, BEFORE the bulk
# reparent. Two cases must both be handled:
# (A) canonical has Post X with epid=N; an "other" source has
# Post Y with epid=N → after bulk UPDATE, (canonical, N)
# collides with itself.
# (B) two different "other" sources each have a Post with
# epid=N; canonical has none → after bulk UPDATE, both
# are repointed to (canonical, N) and the second collides.
# The earlier version of this migration only handled (A); the
# operator's deploy 2026-05-26 tripped (B) at line 139.
# Fix: group ALL Posts in the (artist, platform) by epid; for
# any group with count>1, pick the keep (prefer one already
# under canonical; else lowest id) and merge the rest into it.
all_posts = conn.execute(
text("""
SELECT external_post_id, id, source_id
FROM post
WHERE source_id = :canonical OR source_id = ANY(:others)
ORDER BY external_post_id, id
"""),
{"canonical": canonical_id, "others": other_ids},
).fetchall()
by_epid: dict = {}
for epid, post_id, src_id in all_posts:
by_epid.setdefault(epid, []).append((post_id, src_id))
for _epid, posts in by_epid.items():
if len(posts) <= 1:
continue
# Prefer a Post already under canonical as the keep.
canonical_posts = [p for p in posts if p[1] == canonical_id]
if canonical_posts:
keep_id = canonical_posts[0][0]
else:
keep_id = posts[0][0] # already sorted by id ASC
drop_ids = [p[0] for p in posts if p[0] != keep_id]
for drop_id in drop_ids:
# Pre-delete image_provenance rows under drop_ whose
# image_record_id ALREADY has a provenance under keep —
# the UPDATE below would otherwise repoint them and
# trip uq_image_provenance_image_post (alembic 0021)
# row-by-row before any after-the-fact dedupe could
# run. Operator's v26.05.26.3 deploy 2026-05-26 tripped
# this at line 123.
conn.execute(
text("""
DELETE FROM image_provenance
WHERE post_id = :drop_
AND image_record_id IN (
SELECT image_record_id FROM image_provenance
WHERE post_id = :keep
)
"""),
{"keep": keep_id, "drop_": drop_id},
)
# Now safe to repoint the survivors.
conn.execute(
text("""
UPDATE image_provenance SET post_id = :keep
WHERE post_id = :drop_
"""),
{"keep": keep_id, "drop_": drop_id},
)
conn.execute(
text("""
UPDATE image_record SET primary_post_id = :keep
WHERE primary_post_id = :drop_
"""),
{"keep": keep_id, "drop_": drop_id},
)
conn.execute(
text("DELETE FROM post WHERE id = :drop_"),
{"drop_": drop_id},
)
# STEP 3: Bulk reparent the remaining Posts off the other
# Sources. After step 2, no collisions on
# (canonical, external_post_id) are possible.
conn.execute(
text("""
UPDATE post SET source_id = :canonical
WHERE source_id = ANY(:others)
"""),
{"canonical": canonical_id, "others": other_ids},
)
# STEP 4: Reparent ImageProvenance.source_id (denormalized FK).
# No UNIQUE on source_id; safe bulk update.
conn.execute(
text("""
UPDATE image_provenance SET source_id = :canonical
WHERE source_id = ANY(:others)
"""),
{"canonical": canonical_id, "others": other_ids},
)
# STEP 5: Drop the orphan Sources.
conn.execute(
text("DELETE FROM source WHERE id = ANY(:others)"),
{"others": other_ids},
)
# If the canonical's URL still looks per-post (no campaign URL
# existed among the candidates), rewrite to a synthetic anchor so
# the artist detail page renders something readable.
canonical_url = conn.execute(
text("SELECT url FROM source WHERE id = :id"),
{"id": canonical_id},
).scalar_one()
if _matches_post_url(canonical_url):
slug = conn.execute(
text("SELECT slug FROM artist WHERE id = :id"),
{"id": artist_id},
).scalar_one()
conn.execute(
text("""
UPDATE source
SET url = :new_url, enabled = false
WHERE id = :id
"""),
{
"id": canonical_id,
"new_url": f"sidecar:{platform}:{slug}",
},
)
def downgrade() -> None:
# Lossy migration — orphan Sources deleted, Posts reparented, Posts
# merged. No safe downgrade. If you need to roll back the schema
# invariant, fork from 0021 and re-run filesystem imports.
pass
def _matches_post_url(url: str) -> bool:
"""True if url ends with /posts/<token> (gallery-dl-style per-post URL)."""
import re
return bool(re.search(_POST_URL_RE, url or ""))