unwind/alembic/env.py

import asyncio
from logging.config import fileConfig

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

from alembic import context
from unwind import db, models

# 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)


def is_different_type(
    context,
    inspected_column: sa.Column,
    metadata_column: sa.Column,
    inspected_type: sa.types.TypeEngine,
    metadata_type: sa.types.TypeEngine,
) -> bool | None:
    # We used "TEXT" in our manual SQL, which in SQLite is the same as VARCHAR, but
    # for SQLAlchemy/Alembic looks different.
    equiv_types = [(sa.TEXT, sa.String)]
    for types in equiv_types:
        if isinstance(inspected_type, types) and isinstance(metadata_type, types):
            return False
    return None  # defer to default compare implementation


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.

    """
    context.configure(
        url=db._connection_uri(),
        target_metadata=models.metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        compare_type=is_different_type,
        render_as_batch=True,
    )

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


def do_run_migrations(connection: Connection) -> None:
    context.configure(
        connection=connection,
        target_metadata=models.metadata,
        compare_type=is_different_type,
        render_as_batch=True,
    )

    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.",
        url=db._connection_uri(),
        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."""
    # Support having a (sync) connection passed in from another script.
    if (conn := config.attributes.get("connection")) and isinstance(
        conn, sa.Connection
    ):
        do_run_migrations(conn)
    else:
        asyncio.run(run_async_migrations())


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