old_contents: from __future__ import with_statement
  from alembic import context
  from sqlalchemy import engine_from_config, pool
  from logging.config import fileConfig
  
  # So we can use the same config module for migrations as elsewhere,
  # add ../ to the path. This is a horrid, horrid thing I do, and I
  # blame both python and alembic.
  import sys
  import os.path
  sys.path.append(
      os.path.abspath(
          os.path.join(os.path.dirname(__file__),
                       os.path.pardir)))
  
  from config import config as app_config
  from app.db import db
  
  # this is the Alembic Config object, which provides
  # access to the values within the .ini file in use.
  config = context.config
  
  # Override db connection with our global flask_app config's
  config.set_main_option("sqlalchemy.url",
                         app_config.database_connection_string())
  
  # 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 = db.metadata
  
  # 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)
  
      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()
  
new_contents: from __future__ import with_statement
  from alembic import context
  from sqlalchemy import engine_from_config, pool
  from logging.config import fileConfig
  
  # So we can use the same config module for migrations as elsewhere,
  # add ../ to the path. This is a horrid, horrid thing I do, and I
  # blame both python and alembic.
  import sys
  import os
  sys.path.append(
      os.path.abspath(
          os.path.join(os.path.dirname(__file__),
                       os.path.pardir)))
  
  from app.db import db
  
  # this is the Alembic Config object, which provides
  # access to the values within the .ini file in use.
  config = context.config
  
  # Override db connection with our global flask_app config's
  config.set_main_option("sqlalchemy.url", os.environ['DATABASE_URL'])
  
  # 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 = db.metadata
  
  # 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)
  
      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()
  
subject: Update env.py