Mojo.Backends¶

Mojo abstracts the database interaction away from the object mapper through the use of a backend. These backends offer a ‘safe’ interface for the model prototype to use to access base functions of the driver (such as save, find, find_one etc.).

The back-ends essentially treanslate the input parameters down to the base driver. Currently Mojo ships with two backends: one for Pymongo and the other for Asyncmongo.

Part of the reason for developing Mojo was to be able to easily decide what style of driver to use without having to rewrite many functions (or at least with only minor changes), as the asynchronous style of writing is so different from traditional development while retaining data integrity in your schemas.

Mojo supports both blocking and non-blocking drivers to ensure that both styles of development can be harnessed without forcing the developer down a specific path.

It is easy to add new back-ends by subclassing the Mojo.Backends.base_interface and referencing it in your settings file.

class Mojo.Backends.base_interface.CollectionModelInterface(session, model)¶

The CollectionModelInterface exposes the basic functions of the driver to the ModelPrototype, it will expect to have these functions at least in order to be fully functional:

• find
• find_one
• save
• delete

To create your own back-end, subclass this class and override all the functions with the relevant access functions and parameter styles.

Mojo tends to use Pymongo style dictionary access, it is recommended to try to adhere to this format.

delete(documents, *args, **kwargs)¶

Override this to enable delete in the database

find(*args, **kwargs)¶

Override this to enable find in the database

find_one(*args, **kwargs)¶

Override this to enable find-one in the database

insert(documents, *args, **kwargs)¶

Override this to enable insert in the database

save(document, *args, **kwargs)¶

Override this to enable save in the database

class Mojo.Backends.base_interface.SessionInterface(host='127.0.0.1', port=27017, db_name=None)¶

Session wrapper around the database connection, takes host, port and database information to enable the database session.

If your database has a specific style of connecting, subclass this class and override the _setup_connection function to connect to make the connection available to your backend.

Back-ends access the Session through a session._db property that is assigned during the server boot up:

#Snippet from the Pymongo backend

def find_one(self, *args, **kwargs):
    return_dict = self.session._db[self.collection_name].find_one(*args, **kwargs)
    return self._return_model_object(return_dict)

DATABASE = {
    'backend': 'Mojo.Backends.<BACKEND-MODULE>.<BACKEND>',
    'is_async': False,
    'name': 'test',
    'host': '127.0.0.1',
    'port': 27017
}

DATABASE = {
    'backend': 'Mojo.Backends.AsyncmongoBackend.asyncmongo_backend',
    'is_async': False,
    'name': 'test',
    'host': '127.0.0.1',
    'port': 27017
}

class thisHandler(MojoRequestHandler, MojoAuthMixin, SessionMixin_Async):

    @tornado.web.asynchronous
    @gen.engine
    def get(self):

        this_user = yield gen.Task(Users.find_one_async,{'username':'martin'})

        if this_user:
            print 'Returned user: ', this_user.username

        self.render('template.html', this_user=this_user)

class thisHandler(MojoRequestHandler, MojoAuthMixin, SessionMixin_Async):

        def get(self):

            this_user = Users.find_one({'username':'martin'})

            if this_user:
                print 'Returned user: ', this_user.username

            self.render('template.html', this_user=this_user)