Time for action creating instances

The next method we look at is the constructor the __init__() method. It will be used to create individual instances of an entity. The constructor can be called in two ways:

  • With a single id argument, in which case, an existing record will be retrieved from the database and the instance initialized with the column values of this record, or
  • With a number of keyword arguments to create a new instance and save this as a new database record

The code to implement this behavior looks like the following:


def __init__(self,id=None,**kw):
		for k in kw:
			if not k in self.__class__.columns :
				raise KeyError("unknown column") cursor=self.threadlocal.connection.cursor() if id: if len(kw): raise KeyError("columns ...

Get Python 3 Web Development Beginner's Guide now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.