its a little unfortunate that Invoice.item.distinct() is recursion overflowing
like that, but in general if you want to select distinct Item objects you'd be
saying query(Item).distinct().
not sure I understand what invoices that have distinct items means. I
understand invoices that have items. If Invoice inv1 and inv2 both
reference item im1, are you saying you don't want either of them ? Only
invoice inv3, which references im2, and nobody else references im2 ?
thats a fairly tricky query, probably using EXISTS:
from sqlalchemy.orm import aliased
from sqlalchemy import and_
inv = aliased(Invoice)
query(Invoice).filter(~Invoice.any(and_(Invoice.item_id==inv.item_id,
Invoice.id!=inv.id)))
On Jan 20, 2011, at 6:33 AM, NiL wrote:
hi list,
I have the following (elixir) definitions
class Invoice(Entity):
user_name = Field(Unicode(255))
item = ManyToOne(Item)
class Item(Entity):
item_id = Field(Integer, primary_key=True)
service_id = Field(Unicode(255), primary_key=True)
item_class = Field(Unicode(255), primary_key=True)
I wish to select invoices that have distinct items
(Pdb) Session.query(Invoice.item.distinct())
*** RuntimeError: maximum recursion depth exceeded while calling a
Python object
this works
(Pdb) Session.query(Invoice.item_item_id.distinct())
sqlalchemy.orm.query.Query object at 0x988e7ec
but doesn't lead to the expected result
here is the invoice's table description
CREATE TABLE invoice (
id INTEGER NOT NULL,
user_name VARCHAR(255),
item_item_id INTEGER,
item_service_id VARCHAR(255),
item_item_class VARCHAR(255),
PRIMARY KEY (id),
CONSTRAINT invoice_item_item_id_item_service_id_item_item_class_fk
FOREIGN KEY(item_item_id, item_service_id, item_item_class) REFERENCES
item (item_id, service_id, item_class)
)
How can I achieve my query ?
regards
NIL
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