The example was a bit simplified. In the real process I fetch data from the
database, calculate scores and rankings and then return the result. So it's
not just for database queries, but all calculations.
The reason I'm using cache_property is that many methods in the class use
the same data, so if I call "classinstance.participant_ranking" and
"classinstance.all_participant_rankings", they both use the same cached
data in the class (you cannot calculate ranking of one participant without
calculating it for all). Otherwise I would need to manually check if the
query and calculation has been already made if I don't want to duplicate
the calculation.
I've understood that caches (cache.ram, cache.disk, memcache and redis) are
server level caches. So if my data changes per user, I cannot really use
them(?)
Ykä
On Friday, August 16, 2013 12:39:20 PM UTC+3, Niphlod wrote:
>
> That's a good way to eat up memory in the python process. I would have
> saved a lot of headaches and just used select() with cache, possibly
> exploiting memcache or redis to do the hard job. Don't take this the wrong
> way, the cached_property is a neat trick, it's just not that suitable for
> storing your zillions participant when you'll grow big.
>
> On Friday, August 16, 2013 10:25:32 AM UTC+2, Ykä Marjanen wrote:
>>
>> Hi,
>>
>> After learning Python and web2py deeper, I've restructured my web2py
>> application so that all functions and data are now in classes with lazy
>> methods in my own module. The lazy property class turns any method into a
>> "cached attribute", thus I can make a db query that returns rows and if it
>> is called again it uses the previous result.
>>
>> What this has allowed me to do, is to clean practically all code in my
>> controller as the logic and variables are in a class. Now I just pass the
>> class to the view and the view prints the "attributes" directly without
>> separate call and saving to dict. I've read that some don't like any logic
>> in the view, but that's unavoidable as in the view you need to print stuff
>> depending who the user is and is he logged in or not.
>>
>> I'd like your opinions and comments on my strategy. Here are few
>> simplified examples from my code:
>>
>> Module:
>>
>> class MyClass(object):
>> def __init__(self):
>> self.db = current.db
>>
>> @cached_property
>> def all_participants(self):
>> return self.db(self.db.participant.id>0).select()
>>
>> class MyClassParticipant(MyClass):
>> "Inherits base class"
>> def __init__(self, auth_user_id=None):
>> self.auth_user_id = auth_user_id
>>
>> super(MyClassParticipant, self).__init__()
>>
>> @cached_property
>> def participant_stats(self):
>> return
>> self.db(self.db.participant.auth_user_id==self.auth_user_id).select()
>>
>> Controller:
>>
>> def index():
>> if auth.user:
>> xclassinstance =
>> module.MyClassParticipant(auth_user_id=auth.user_id)
>> else:
>> xclassinstance = module.MyClass()
>>
>> return dict(xclassinstance=xclassinstance)
>>
>> View:
>>
>> {{if auth.user:}}
>> Your ranking is {{=xclassinstance.participant_stats.ranking}}
>>
>> Rankings of all participants
>> <br />
>> {{for participant in xclassinstance.all_participants:}}
>> {{=participant.name}} ranking is {{=participant.ranking}}
>> <br />
>>
>> Ykä
>>
>>
>>
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