68 lines
2.0 KiB
Python
68 lines
2.0 KiB
Python
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"""Database engine + session.
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Reads DATABASE_URL from the environment (provisioned Postgres). The engine is
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created with a short connect timeout and a probe: if Postgres is unreachable at
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startup, we fall back to a local SQLite file so the app still runs (Preview,
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offline dev). The rest of the app never chooses a database — it imports
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``SessionLocal`` and ``engine`` from here.
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"""
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from __future__ import annotations
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import os
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from collections.abc import Generator
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from sqlalchemy import create_engine, text
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from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker
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class Base(DeclarativeBase):
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pass
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def _normalize(url: str) -> str:
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# SQLAlchemy + psycopg3 wants the postgresql+psycopg driver.
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if url.startswith("postgresql://"):
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return url.replace("postgresql://", "postgresql+psycopg://", 1)
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if url.startswith("postgres://"):
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return url.replace("postgres://", "postgresql+psycopg://", 1)
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return url
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def _make_engine():
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url = os.getenv("DATABASE_URL", "").strip()
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if url:
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pg_url = _normalize(url)
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try:
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eng = create_engine(
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pg_url,
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pool_pre_ping=True,
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connect_args={"connect_timeout": 5},
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)
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with eng.connect() as conn:
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conn.execute(text("SELECT 1"))
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print("[db] using Postgres")
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return eng
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except Exception as exc: # noqa: BLE001
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print(f"[db] Postgres unreachable ({exc}); falling back to SQLite")
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sqlite_path = os.path.join(os.path.dirname(__file__), "..", "app_fallback.db")
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eng = create_engine(
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f"sqlite:///{os.path.abspath(sqlite_path)}",
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connect_args={"check_same_thread": False},
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)
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print("[db] using SQLite fallback")
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return eng
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engine = _make_engine()
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SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)
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def get_db() -> Generator[Session, None, None]:
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db = SessionLocal()
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try:
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yield db
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finally:
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db.close()
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