Interface

Access and CRUD operations in the various types of databases are standardized in two objects: Connection and Session objects.

Constructors

Access to the database is made available through Connection objects. The module must provide the following constructor for these:

>>> connection = Connection(*args, **kwargs)

The Connection object allows you to access the database and operate directly at the database server level. This object has a connect method that returns a Session object. It takes a number of parameters which are database dependent.

>>> session = connection.connect(*args, **kwargs)

With Session object you can operate directly on the database data specified when creating the Connection object.

Note

This division of objects allows you to have more flexibility in case you want to change databases. It is not necessary to create a new object to connect to a different database.

Globals

api_level is a global variable to check compatibility with the names defined in this document. Currently the level is 1.0.

CONNECTION is a global variable where to save a global Connection object.

SESSION is a global variable where to save a global Session object.

Exceptions

All defined exceptions derive from the general exception Error based on Exception class, which tends not to be used directly.

>>> raise Error("Don't use this, but its subclasses!")

Name	Base	Description
Error	Exception	Exception that is the base class of all other error exceptions. Use only for checks.
UnknownError	Error	Exception raised when an unspecified error occurred.
ConnectError	Error	Exception raised for errors that are related to the database connection.
CloseError	Error	Exception raised for errors that are related to the database close connection.
DatabaseError	Error	Exception raised for errors that are related to the database, generally.
DatabaseCreationError	DatabaseError	Exception raised for errors that are related to the creation of a database.
DatabaseDeletionError	DatabaseError	Exception raised for errors that are related to the deletion of a database.
SessionError	Error	Exception raised for errors that are related to the session, generally.
SessionInsertingError	SessionError	Exception raised for errors that are related to the inserting data on a database session.
SessionUpdatingError	SessionError	Exception raised for errors that are related to the updating data on a database session.
SessionDeletingError	SessionError	Exception raised for errors that are related to the deletion data on a database session.
SessionClosingError	SessionError	Exception raised for errors that are related to the closing database session.
SessionFindingError	SessionError	Exception raised for errors that are related to the finding data on a database session.
SessionACLError	SessionError	Exception raised for errors that are related to the grant or revoke permission on a database.
SelectorError	Error	Exception raised for errors that are related to the selectors in general.
SelectorAttributeError	SelectorError	Exception raised for errors that are related to the selectors attribute.

The tree of exceptions:

Exception
|__Error
   |__UnknownError
   |__ConnectError
   |__CloseError
   |__DatabaseError
   |  |__DatabaseCreationError
   |  |__DatabaseDeletionError
   |__SessionError
   |  |__SessionInsertingError
   |  |__SessionUpdatingError
   |  |__SessionDeletingError
   |  |__SessionClosingError
   |  |__SessionFindingError
   |  |__SessionACLError
   |__SelectorError
      |__SelectorAttributeError

Selectors

NOSQL databases do not use SQL syntax, or if they do, it is encapsulated in a shell or interpreter. The selection queries will be driven through Selector objects which will then be passed to the find method of a Session object.

>>> selector = Selector(*args, **kwargs)
>>> session.find(selector)

Note

A string representing the language of the selector can also be passed to the find method.