from __future__ import with_statement

from alembic import context

from sqlalchemy import engine_from_config, pool

from logging.config import fileConfig

# 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.

fileConfig(config.config_file_name)

# add your model's MetaData object here

# for 'autogenerate' support

# from myapp import mymodel

# target_metadata = mymodel.Base.metadata

target_metadata = None

# 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():

    """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)

    with context.begin_transaction():

        context.run_migrations()

def run_migrations_online():

    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine

    and associate a connection with the context.

    """

    engine = engine_from_config(

                config.get_section(config.config_ini_section),

                prefix='sqlalchemy.',

                poolclass=pool.NullPool)

    connection = engine.connect()

    context.configure(

                connection=connection,

                target_metadata=target_metadata

                )

    try:

        with context.begin_transaction():

            context.run_migrations()

    finally:

        connection.close()

if context.is_offline_mode():

    run_migrations_offline()

else:

    run_migrations_online()