Database tier

You can use SQLAlchemy or its declarative layer Elixir with Nagare. For each request received, Nagare creates a database transaction which is commited at the end of the request handling or rollbacked if an exception is raised.

The database connection is activated and configurated in the [database] section of the application configuration file as described in ApplicationConfiguration#database-section. One of the parameters in this section is the location of the __metadata__ object of SQLAlchemy:

• which must be explicitly created:

  from elixir import *
  from sqlalchemy import MetaData
  
  __metadata__ = MetaData()
  
  # Database definitions
  ...
  

• which Nagare automatically binds to the database engine when the application is launched

• where your code must explicitly register the table definitions if you are using SQLAlchemy only

• where Elixir automatically register the entities defined (see for example the Wiki entities definition at examples/nagare/examples/wiki/wikidata.py)