feat(fc2a): add TagService — find-or-create, autocomplete, image association

Validates kind/fandom rules at the service layer: fandom_id only allowed
for kind='character', and must reference an existing kind='fandom' tag.
Autocomplete ranking: exact match > prefix match > substring, tie-broken
by image_count descending. Image-tag association uses INSERT ON CONFLICT
DO NOTHING for idempotent re-tagging.

conftest.py adds a transactional AsyncSession fixture; each test rolls
back so they don't pollute each other. Also includes a sync Session
fixture (db_sync) for the Importer tests in Task 5.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
2026-05-14 12:04:48 -04:00
parent 4cb319b393
commit f6c7117231
4 changed files with 341 additions and 0 deletions
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"""Business-logic services consumed by API blueprints and Celery tasks."""
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"""Tag CRUD + autocomplete + image-tag association."""
from collections.abc import Sequence
from dataclasses import dataclass
from sqlalchemy import and_, case, func, select
from sqlalchemy.dialects.postgresql import insert
from sqlalchemy.ext.asyncio import AsyncSession
from ..models import Tag, TagKind, image_tag
class TagValidationError(ValueError):
"""Raised when tag construction breaks the kind/fandom rules."""
@dataclass(frozen=True)
class TagAutocompleteHit:
id: int
name: str
kind: str
fandom_id: int | None
fandom_name: str | None
image_count: int
class TagService:
def __init__(self, session: AsyncSession):
self.session = session
async def find_or_create(
self, name: str, kind: TagKind, fandom_id: int | None = None
) -> Tag:
"""Upserts (name, kind, fandom_id) into the tag table.
Validates kind/fandom rules before touching the DB:
- fandom_id may only be set when kind == TagKind.character
- if fandom_id is set, the referenced tag must exist and have
kind == TagKind.fandom
"""
name = name.strip()
if not name:
raise TagValidationError("Tag name cannot be empty")
if fandom_id is not None and kind != TagKind.character:
raise TagValidationError(
"fandom_id is only valid for character tags"
)
if fandom_id is not None:
fandom = await self.session.get(Tag, fandom_id)
if fandom is None or fandom.kind != TagKind.fandom:
raise TagValidationError(
f"fandom_id {fandom_id} does not reference a fandom tag"
)
# Upsert via INSERT ... ON CONFLICT DO NOTHING. We can't use the
# uniqueness index name directly (it's a partial coalesce-based
# expression), so we re-select after insert.
stmt = (
select(Tag)
.where(Tag.name == name)
.where(Tag.kind == kind)
.where(
Tag.fandom_id.is_(None) if fandom_id is None else Tag.fandom_id == fandom_id
)
)
existing = (await self.session.execute(stmt)).scalar_one_or_none()
if existing:
return existing
new_tag = Tag(name=name, kind=kind, fandom_id=fandom_id)
self.session.add(new_tag)
await self.session.flush()
return new_tag
async def autocomplete(
self,
query: str,
kind: TagKind | None = None,
limit: int = 20,
) -> list[TagAutocompleteHit]:
"""ILIKE search ranked exact > prefix > substring, then by image count.
Returns at most `limit` hits.
"""
q = (query or "").strip()
if not q:
return []
match_rank = case(
(func.lower(Tag.name) == q.lower(), 0),
(func.lower(Tag.name).startswith(q.lower()), 1),
else_=2,
)
fandom_alias = Tag.__table__.alias("fandom_lookup")
image_count = (
select(func.count(image_tag.c.image_record_id))
.where(image_tag.c.tag_id == Tag.id)
.correlate(Tag.__table__)
.scalar_subquery()
)
stmt = (
select(
Tag.id,
Tag.name,
Tag.kind,
Tag.fandom_id,
fandom_alias.c.name.label("fandom_name"),
image_count.label("image_count"),
)
.select_from(Tag.__table__.outerjoin(
fandom_alias, Tag.fandom_id == fandom_alias.c.id
))
.where(func.lower(Tag.name).like(f"%{q.lower()}%"))
.order_by(match_rank.asc(), image_count.desc(), Tag.name.asc())
.limit(limit)
)
if kind is not None:
stmt = stmt.where(Tag.kind == kind)
rows = (await self.session.execute(stmt)).all()
return [
TagAutocompleteHit(
id=r.id,
name=r.name,
kind=r.kind.value if hasattr(r.kind, "value") else r.kind,
fandom_id=r.fandom_id,
fandom_name=r.fandom_name,
image_count=r.image_count or 0,
)
for r in rows
]
async def add_to_image(self, image_id: int, tag_id: int, source: str = "manual") -> None:
"""Idempotent: re-adding an existing tag does nothing."""
stmt = insert(image_tag).values(
image_record_id=image_id, tag_id=tag_id, source=source
)
stmt = stmt.on_conflict_do_nothing(
index_elements=["image_record_id", "tag_id"]
)
await self.session.execute(stmt)
async def remove_from_image(self, image_id: int, tag_id: int) -> None:
await self.session.execute(
image_tag.delete().where(
and_(
image_tag.c.image_record_id == image_id,
image_tag.c.tag_id == tag_id,
)
)
)
async def list_for_image(self, image_id: int) -> Sequence[Tag]:
stmt = (
select(Tag)
.join(image_tag, image_tag.c.tag_id == Tag.id)
.where(image_tag.c.image_record_id == image_id)
.order_by(Tag.kind.asc(), Tag.name.asc())
)
return (await self.session.execute(stmt)).scalars().all()
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"""Shared pytest fixtures.
The async db fixture provides an AsyncSession bound to a transaction that
gets rolled back after each test. CI provisions a real Postgres + pgvector
(see .forgejo/workflows/ci.yml), so tests exercise the actual schema and
migration code paths.
"""
import os
import pytest
import pytest_asyncio
from sqlalchemy import create_engine
from sqlalchemy.ext.asyncio import (
AsyncSession,
async_sessionmaker,
create_async_engine,
)
from sqlalchemy.orm import sessionmaker
def _async_database_url() -> str:
user = os.environ.get("DB_USER", "fabledcurator")
password = os.environ["DB_PASSWORD"]
host = os.environ.get("DB_HOST", "postgres")
port = os.environ.get("DB_PORT", "5432")
name = os.environ.get("DB_NAME", "fabledcurator_test")
return f"postgresql+asyncpg://{user}:{password}@{host}:{port}/{name}"
def _sync_database_url() -> str:
user = os.environ.get("DB_USER", "fabledcurator")
password = os.environ["DB_PASSWORD"]
host = os.environ.get("DB_HOST", "postgres")
port = os.environ.get("DB_PORT", "5432")
name = os.environ.get("DB_NAME", "fabledcurator_test")
return f"postgresql+psycopg://{user}:{password}@{host}:{port}/{name}"
@pytest_asyncio.fixture
async def engine():
e = create_async_engine(_async_database_url(), future=True)
yield e
await e.dispose()
@pytest_asyncio.fixture
async def db(engine) -> AsyncSession:
Session = async_sessionmaker(engine, expire_on_commit=False)
async with Session() as session:
await session.begin()
try:
yield session
finally:
await session.rollback()
@pytest.fixture
def sync_engine():
e = create_engine(_sync_database_url(), future=True)
yield e
e.dispose()
@pytest.fixture
def db_sync(sync_engine):
"""Synchronous Session bound to a savepoint — used by Importer tests
(the Importer is sync-only by design)."""
SyncSession = sessionmaker(sync_engine, expire_on_commit=False)
with SyncSession() as session:
session.begin()
try:
yield session
finally:
session.rollback()
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import pytest
from backend.app.models import TagKind
from backend.app.services.tag_service import TagService, TagValidationError
@pytest.mark.asyncio
async def test_find_or_create_creates(db):
svc = TagService(db)
t = await svc.find_or_create("Alice", TagKind.character, fandom_id=None)
assert t.id is not None
assert t.name == "Alice"
assert t.kind == TagKind.character
@pytest.mark.asyncio
async def test_find_or_create_idempotent(db):
svc = TagService(db)
a = await svc.find_or_create("Bob", TagKind.artist)
b = await svc.find_or_create("Bob", TagKind.artist)
assert a.id == b.id
@pytest.mark.asyncio
async def test_same_name_different_kind_coexists(db):
svc = TagService(db)
artist = await svc.find_or_create("Forge", TagKind.artist)
series = await svc.find_or_create("Forge", TagKind.series)
assert artist.id != series.id
@pytest.mark.asyncio
async def test_fandom_id_requires_character(db):
svc = TagService(db)
fandom = await svc.find_or_create("Naruto", TagKind.fandom)
with pytest.raises(TagValidationError, match="character"):
await svc.find_or_create("Bob", TagKind.artist, fandom_id=fandom.id)
@pytest.mark.asyncio
async def test_fandom_id_must_reference_fandom(db):
svc = TagService(db)
artist = await svc.find_or_create("X", TagKind.artist)
with pytest.raises(TagValidationError, match="fandom"):
await svc.find_or_create("Y", TagKind.character, fandom_id=artist.id)
@pytest.mark.asyncio
async def test_character_with_fandom(db):
svc = TagService(db)
fandom = await svc.find_or_create("Naruto", TagKind.fandom)
char = await svc.find_or_create("Sasuke", TagKind.character, fandom_id=fandom.id)
assert char.fandom_id == fandom.id
@pytest.mark.asyncio
async def test_character_same_name_different_fandoms(db):
svc = TagService(db)
f1 = await svc.find_or_create("Series A", TagKind.fandom)
f2 = await svc.find_or_create("Series B", TagKind.fandom)
c1 = await svc.find_or_create("Alice", TagKind.character, fandom_id=f1.id)
c2 = await svc.find_or_create("Alice", TagKind.character, fandom_id=f2.id)
assert c1.id != c2.id
@pytest.mark.asyncio
async def test_empty_name_raises(db):
svc = TagService(db)
with pytest.raises(TagValidationError):
await svc.find_or_create(" ", TagKind.general)
@pytest.mark.asyncio
async def test_autocomplete_ranking(db):
svc = TagService(db)
await svc.find_or_create("alice", TagKind.character)
await svc.find_or_create("alicent", TagKind.character)
await svc.find_or_create("malice", TagKind.character)
hits = await svc.autocomplete("alice")
# exact match first, then prefix, then substring
names = [h.name for h in hits]
assert names[0] == "alice"
assert names[1] == "alicent"
assert names[2] == "malice"
@pytest.mark.asyncio
async def test_autocomplete_kind_filter(db):
svc = TagService(db)
await svc.find_or_create("Foo", TagKind.artist)
await svc.find_or_create("Foo", TagKind.character)
hits = await svc.autocomplete("Foo", kind=TagKind.artist)
assert len(hits) == 1
assert hits[0].kind == "artist"
@pytest.mark.asyncio
async def test_autocomplete_empty_query_returns_nothing(db):
svc = TagService(db)
await svc.find_or_create("Foo", TagKind.artist)
assert await svc.autocomplete("") == []