backend/migrations/env.py

import asyncio
from logging.config import fileConfig

from sqlalchemy import pool
from sqlalchemy.engine import Connection
from sqlalchemy.ext.asyncio import async_engine_from_config

from alembic import context

# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config

# Interpret the config file for Python logging.
# This line sets up loggers basically.
if config.config_file_name is not None:
    fileConfig(config.config_file_name)

import os
import sys
from dotenv import load_dotenv

# Load .env from workspace root if present
load_dotenv(os.path.join(os.path.dirname(os.path.dirname(os.path.dirname(__file__))), ".env"))
sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))

# Import unified production model registry
from app.models import Base
target_metadata = Base.metadata

# Load DATABASE_URL from environment or fallback config
database_url = os.environ.get("DATABASE_URL")
if not database_url:
    try:
        from database.db import DATABASE_URL
        database_url = DATABASE_URL
    except ImportError:
        database_url = "postgresql+asyncpg://datavision:datavision_dev@localhost:5433/datavision"

if database_url.startswith("postgres://"):
    database_url = database_url.replace("postgres://", "postgresql+asyncpg://", 1)
elif database_url.startswith("postgresql://") and not database_url.startswith("postgresql+asyncpg://"):
    database_url = database_url.replace("postgresql://", "postgresql+asyncpg://", 1)

config.set_main_option("sqlalchemy.url", database_url.replace('%', '%%'))

# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.


def run_migrations_offline() -> None:
    """Run migrations in 'offline' mode.

    This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
    )

    with context.begin_transaction():
        context.run_migrations()


def do_run_migrations(connection: Connection) -> None:
    context.configure(connection=connection, target_metadata=target_metadata)

    with context.begin_transaction():
        context.run_migrations()


async def run_async_migrations() -> None:
    """In this scenario we need to create an Engine
    and associate a connection with the context.

    """

    connectable = async_engine_from_config(
        config.get_section(config.config_ini_section, {}),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

    async with connectable.connect() as connection:
        await connection.run_sync(do_run_migrations)

    await connectable.dispose()


def run_migrations_online() -> None:
    """Run migrations in 'online' mode."""

    asyncio.run(run_async_migrations())


if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()