[sqlalchemy] Re: how to make a query for multilevel reference?
okay, how would u do something like (person.address1.country.name == 'France' or person.address2.country.name == 'Germany') note there are 2 different address1 and address2 fields of the person. and, how would this be like: (person.address1.country.name == 'France' or person.company.name == 'Acme') --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: how to make a query for multilevel reference?
svilen wrote: But then query.select_by( name='whatever') may find different .name 's in the obj.hierarchy depending on dict.hashes/iteration, within same run or between different runs, returning very different queries... then just use select() for more specificity. Which means - cripple the _locate_prop() to look only 1 level down, making it predictable. it will match the first level it finds. its predictable. or.. let the wishful ones to hang themselves using literal strings into **kwargs ... (-:) Matching for key-subpaths within a key-tree (that is, object-attr-hierarchy) is a very powerful thing.. no need for wishing... just make yourself a MapperExtension that plugs whatever functionality you want into the select_by() method. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: how to make a query for multilevel reference?
Which means - cripple the _locate_prop() to look only 1 level down, making it predictable. it will match the first level it finds. its predictable. you have multiple levels of dictionaries. Traversing them is not really predictable (although stable if noone changes them, within same run). So if there is: class Address: street =Text() class Person: address_real = Address() address_official = Address() mother = Person() traversing through some person's attributes may in one run first find .street in person.address_real, in another run (or later in same run) in person.address_official. thus it's not really predictable. okay, i'm not arguing, maybe just put some warning about it in the doco or something. Making some dictionaries ordered maybe also a way, if dynamic adding of attributes/relations is not allowed. ciao svil --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: how to make a query for multilevel reference?
yes, if you have two relations at the *same* level, both of which will lead to the same named property within, then select_by() by itself is useless. if you are querying for a relaton that you think is local, and its not and then it magically traverses down and finds the wrong property, then its wrong regardless of whether multiple matching relationships exist or not...you expected it to only remain within the first level. the error in that behavior will become apparent very quickly. if you are relying upon the deep traversal behavior, then you'd better know what youre doing. so far, nobody's ever had a problem with it. my litmus test to remove an API and replace with something else usually starts with users keep getting errors with the current API, so this is not hitting that point yet. the best way by far is to just use SelectResults and be explicit. I should add a select_by() to SelectResults though. im not thrilled with the inconvenience of using SelectResults and wish I had written Query to be more like it in the first place; but it is a different approach than Query and I would rather not conflate the two approaches. On Jan 23, 2007, at 12:53 PM, svilen wrote: Which means - cripple the _locate_prop() to look only 1 level down, making it predictable. it will match the first level it finds. its predictable. you have multiple levels of dictionaries. Traversing them is not really predictable (although stable if noone changes them, within same run). So if there is: class Address: street =Text() class Person: address_real = Address() address_official = Address() mother = Person() traversing through some person's attributes may in one run first find .street in person.address_real, in another run (or later in same run) in person.address_official. thus it's not really predictable. okay, i'm not arguing, maybe just put some warning about it in the doco or something. Making some dictionaries ordered maybe also a way, if dynamic adding of attributes/relations is not allowed. ciao svil --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: how to make a query for multilevel reference?
Lets have a Person having .address having .country having .name.
How would give-me-persons-which-live-in France be expressed in
SA (sorry for my SQL ignorance)?
e.g. all-persons-for-which person.address.country.name ==
'France'
http://www.sqlalchemy.org/docs/datamapping.myt#datamapping_selectrelations_relselectby
Unfortunately I think if your Person has a name attribute too you
have no alternative but to write the join out the long way. (I'd
love to find out I'm wrong though. :)
ahha. Maybe the underlying query._locate_prop() can be tweaked to
accept hierarchical keys in some form (e.g. a.b.c.d.e.f ), and then
not search but just follow the hierarchy...
e.g.
#put in orm.query.Query
#will search for the spec.hierarchycal key as a subkey, not just as
root)
def _locate_prop(self, key, start=None):
import properties
keys = []
seen = util.Set()
def search_for_prop(mapper_, fullkey):
if mapper_ in seen:
return None
seen.add(mapper_)
key = fullkey[0]
if mapper_.props.has_key(key):
prop = mapper_.props[key]
if len(fullkey)==1:
if isinstance(prop, properties.SynonymProperty):
prop = mapper_.props[prop.name]
if isinstance(prop, properties.PropertyLoader):
keys.insert(0, prop.key)
return prop
else:
props = [prop]
fullkey = fullkey[1:]
for prop in mapper_.props.values():
if not isinstance(prop, properties.PropertyLoader):
continue
x = search_for_prop(prop.mapper, fullkey)
if x:
keys.insert(0, prop.key)
return x
return None
p = search_for_prop(start or self.mapper, key.split('.') )
if p is None:
raise exceptions.InvalidRequestError(Cant locate property
named '%s' % key)
return [keys, p]
..
person = Person()
person.address = Address()
person.address.country = Country()
person.address.country.name = 'france'
session.save(person)
q1 = session.query(D).select_by( name='france')
q2 = session.query(D).select_by( **{'country.name':'france'} )
q3 = session.query(D).select_by( **{'address.country.name':'france'} )
assert q1 == q2 == q3
...
do try it, it seems to work...
have fun
svil
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[sqlalchemy] Re: how to make a query for multilevel reference?
how about q = session.query(D) q.select(q.join_via([address, country]) (Country.c.name == 'france')) or q = SelectResults(session.query(D)) q.join_to(address).join_to(country).select(Country.c.name=='france') im not down with shoving literal strings into **kwargs at all --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: how to make a query for multilevel reference?
Hey what's with the bitwise AND operator? Does that actually work to AND together parts of WHERE clauses? On 1/21/07, Michael Bayer [EMAIL PROTECTED] wrote: how about q = session.query(D) q.select(q.join_via([address, country]) (Country.c.name == 'france')) or q = SelectResults(session.query(D)) q.join_to(address).join_to(country).select(Country.c.name=='france') im not down with shoving literal strings into **kwargs at all --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: how to make a query for multilevel reference?
yes, although its a little inconvenient because it takes a high precedence in the order of operations (thus you have to put () around all expressions) --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
