parameters: ()
docstring: Run migrations in 'online' mode.
  
      In this scenario we need to create an Engine
      and associate a connection with the context.
docstring_summary: Run migrations in 'online' mode.
docstring_tokens: Run migrations in online mode .
function: 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.
  
      """
  
      # this callback is used to prevent an auto-migration from being generated
      # when there are no changes to the schema
      # reference: http://alembic.readthedocs.org/en/latest/cookbook.html
      def process_revision_directives(context, revision, directives):
          if getattr(config.cmd_opts, 'autogenerate', False):
              script = directives[0]
              if script.upgrade_ops.is_empty():
                  directives[:] = []
                  logger.info('No changes in schema detected.')
  
      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,
                        process_revision_directives=process_revision_directives,
                        **current_app.extensions['migrate'].configure_args)
  
      try:
          with context.begin_transaction():
              context.run_migrations()
      finally:
          connection.close()
function_tokens: def run_migrations_online ( ) : # this callback is used to prevent an auto-migration from being generated # when there are no changes to the schema # reference: http://alembic.readthedocs.org/en/latest/cookbook.html def process_revision_directives ( context , revision , directives ) : if getattr ( config . cmd_opts , 'autogenerate' , False ) : script = directives [ 0 ] if script . upgrade_ops . is_empty ( ) : directives [ : ] = [ ] logger . info ( 'No changes in schema detected.' ) 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 , process_revision_directives = process_revision_directives , * * current_app . extensions [ 'migrate' ] . configure_args ) try : with context . begin_transaction ( ) : context . run_migrations ( ) finally : connection . close ( )