+class ORMObject(object):
+ """
+ ORMObject is a base class for all ORM classes mapped by SQLalchemy. All
+ derived classes must implement the summary() method.
+ """
+
+ def properties(self):
+ '''
+ This method should be implemented by all derived classes and returns a
+ list of the important properties. The properties 'created' and
+ 'modified' will be added automatically. A suffix '_count' should be
+ added to properties that are lists or query objects. The most important
+ property name should be returned as the first element in the list
+ because it is used by repr().
+ '''
+ return []
+
+ def json(self):
+ '''
+ Returns a JSON representation of the object based on the properties
+ returned from the properties() method.
+ '''
+ data = {}
+ # add created and modified
+ all_properties = self.properties() + ['created', 'modified']
+ for property in all_properties:
+ # check for list or query
+ if property[-6:] == '_count':
+ value = getattr(self, property[:-6])
+ if hasattr(value, '__len__'):
+ # list
+ value = len(value)
+ elif hasattr(value, 'count'):
+ # query
+ value = value.count()
+ else:
+ raise KeyError('Do not understand property %s.' % property)
+ else:
+ # plain object
+ value = getattr(self, property)
+ if value is None:
+ # skip None
+ pass
+ elif isinstance(value, ORMObject):
+ # use repr() for ORMObject types
+ value = repr(value)
+ else:
+ # we want a string for all other types because json cannot
+ # everything
+ value = str(value)
+ data[property] = value
+ return json.dumps(data)
+
+ def classname(self):
+ '''
+ Returns the name of the class.
+ '''
+ return type(self).__name__
+
+ def __repr__(self):
+ '''
+ Returns a short string representation of the object using the first
+ element from the properties() method.
+ '''
+ primary_property = self.properties()[0]
+ value = getattr(self, primary_property)
+ return '<%s %s>' % (self.classname(), str(value))
+
+ def __str__(self):
+ '''
+ Returns a human readable form of the object using the properties()
+ method.
+ '''
+ return '<%s %s>' % (self.classname(), self.json())
+
+__all__.append('ORMObject')
+
+################################################################################
+
+class Architecture(ORMObject):