[storm] Query questions and misc. comments

[Håvard Gulldahl]

[Re-sending the reply that I by accident sent to Morten privately]


Hi Morten,

I feel your frustration. I've only just started using storm myself.
While the tutorial is great for learning the tutorial, all the other
stuff is a bit more veiled. In my experience, the best way to explore
storm is

1) study the source files  (obviously ;)
2) turn on debugging, since you'll see the sql query that storm
expands from your code:

import storm.database
storm.database.DEBUG = True


On 12/9/07, Morten Siebuhr <msiebuhr at sbhr.dk> wrote:
>      1. It is in no way obvious from the tutorial or manual-page how one
>         does stuff like NOT, LIKE, IN, AND and OR in Storm. I've seen

It's not obvious at first. After a while it's just easy as pie. Check
it (code semi-tested):

LIKE:
store.find(klass, klass.col.like('%skabelone'))

NOT:
from storm.expr import Not
store.find(klass, Not(klass.col < 10))

IN:
from storm.expr import In
store.find(klass, In(klass.id, [1,2,3,10,11,12]))

AND/OR:
from storm.expr import And, Or
expr1 = And(klass.col == 2, klass.disabled == False)
store.find(klass, Or(klass.sticky, expr1))


So, since this is all serializable, you can easily build up a python
list of expressions, and then, And() or Or() it together, depending on
your application:

expressions = []
#... loop through input and build atomic expressions, e.g. ...
#  expressions += [ stormer.lastname.like('%buhr') ]
#  expressions += [ stormer.gender == 'Male' ]
# and then:
store.find(stormer, And(*expressions))



>      2. From reading the generated documentation - it seems sub-queries
>         are possible, but I can't really figure out how.

SELECT:
from storm.expr import Select, In
expr1 = Select(klass2, klass2.enabled == True)
store.find(klass, In(klass.foreignId, expr1))


>      3. How - if at all - does Storm handle VIEWs? I'd really like to
>         hide away some of the complex queries, but I'd prefer not to
>         give up using Storm-objects.

I don't know anything about this.

Hope this helps,

Håvard

--
Håvard Gulldahl <havard at gulldahl.no>