timpo

“

The basics

A settings file is just a Python module with module-level variables.

Here are a couple of example settings:

DEBUG = False
DEFAULT_FROM_EMAIL = 'webmaster@example.com'
TEMPLATE_DIRS = ('/home/templates/mike', '/home/templates/john')

Because a settings file is a Python module, the following apply:

• It doesn't allow for Python syntax errors.

• It can assign settings dynamically using normal Python syntax. For example:

  MY_SETTING = [str(i) for i in range(30)]
  

• It can import values from other settings files.

”

“

How can I subclass Table/Column to provide certain behaviors/configurations? ¶

Table and Column can be subclassed but not without using code which is specific to SQLAlchemy internals (which can change at any time). To date, we have yet to see a use case for "subclassing" which goes beyond specifying a particular set of constructs and options during creation. Therefore, it is much easier and 100% future-proof to use functions that return pre-configured Table and Column instances instead.

A Table example:

def TimeStampTable(*args, **kwargs):
    args = args + (Column('created_at', DateTime, nullable=False, default=datetime.now),
                   Column('updated_at', DateTime, onupdate=datetime.now)
                  )
    return Table(*args, **kwargs)

my_table = TimeStampTable('my_table', metadata, 
    Column('id', Integer, primary_key=True)
)

A Column example:

def NotNullColumn(*args, **kwargs):
    kwargs.setdefault('null', False)
    return Column(*args, **kwargs)

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