On 1/26/11 6:13 AM, Wade Leftwich wrote:
I've been dealing with similar issues on my first-ever Pyramid
project, also using sqlalchemy and traversal.
This may be indirection overkill, but I separated Context objects from
Data objects. Note this is a reporting application, so it's more into
displaying the results of queries than in interacting with individual
objects in the model. The Context objects organize the tree and
queries the database.
# in resources package
# sqlalchemy declarative classes
from orm import Site
from orm import SiteMonth
DBSession =
scoped_session(sessionmaker(extension=ZopeTransactionExtension()))
class Context(object):
__name__ = None
__parent__ = None
children = {}
def __getitem__(self, name):
return self.children[name]
def add_child(self, child, name):
child.__name__ = name
child.__parent__ = self
self.children[name] = child
maybe you omitted code for brevity, but you don't really want `children`
to be defined at the class level, do you? i.e. you have an
__init__(self) method that sets `self.children = {}`, either here or in
all of the base classes right? otherwise all of your instances are
sharing the same children:
>>> class B(object):
... foo = {}
...
>>> class C(B):
... pass
...
>>> b = B()
>>> c = C()
>>> b.foo
{}
>>> c.foo
{}
>>> b.foo['bar'] = 'baz'
>>> b.foo
{'bar': 'baz'}
>>> c.foo
{'bar': 'baz'}
also, while this isn't necessary, you could override __setitem__ to do
the same thing add_child is doing, then you could maintain the
dictionary-like API, like so:
root['report'] = Report()
and if you subclass from dict or UserDict, and define __delitem__ and
keys methods, you can get the rest of the dictionary API pretty much for
free.
-r
class Root(Context):
def get_sites(self, like=None):
session = DBSession()
query = session.query(Site).order_by(Site.host)
if like:
if '%' not in like:
like += '%'
query = query.filter(Site.host.like(like))
return iter(query)
class Report(Context):
def get_report(self, hosts=None, startdate=None, enddate=None):
session = DBSession()
query = session.query(SiteMonth).order_by(SiteMonth.host,
SiteMonth.month)
if hosts:
query = query.filter(SiteMonth.host.in_(hosts))
if startdate:
query = query.filter(SiteMonth.month>= startdate)
if enddate:
query = query.filter(SiteMonth.month<= enddate)
return iter(query)
root = Root()
root.add_child(Report(), 'report')
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