Products collection domain service

As with our entity classes, we start by defining a base class for all the domain services. What the base class provides for us is a property that represents instances of pymongo.database.Database and db.mongodb.connection.Connection.

The constructor initializes these two properties using the connection to retrieve the database instance:

# sweetscomplete.domain.base
class Base :    
    db = None
    conn = None        
    def __init__(self, conn, database) :
        self.conn = conn
        self.db   = conn.getDatabase(database)

We then define a domain service class called sweetscomplete.domain.product.ProductService that inherits from the base class:

# sweetscomplete.domain.product
from sweetscomplete.domain.base import Base
from sweetscomplete.entity.product import Product
class ProductService(Base) :
    # useful methods definitions go here

We are then free to add useful methods as needed. These methods are wrappers for core pymongo collection methods including...