Hi Guys,
Currently I'm maintaining a python-2.5 (pylons) webapplication, which
uses sqlaclhemy as its ORM.
I've been messing around for some time with this (quite stupid)
problem, but still can't het it to work the way I want it to.
Situation:
There's 2 tables, Fiber and Line. A line consists of a (or maybe in
the future, more) Fiber.
My definitions:
fiberdb=# \d "Fiber";
Table "public.Fiber"
Column | Type
| Modifiers
------------------------+--------------------------
+-----------------------------------------------------------
FiberID | integer | not null default
nextval('"Fiber_FiberID_seq"'::regclass)
LineName | character varying(50) |
FiberUsed | character(1) |
Indexes:
"PRI_Fiber" PRIMARY KEY, btree ("FiberID")
"FKI_Fiber_Line" btree ("LineName")
"fki_" btree ("LineName")
Foreign-key constraints:
"FK_Fiber_Line" FOREIGN KEY ("LineName") REFERENCES
"Line"("LineName") ON UPDATE CASCADE ON DELETE RESTRICT
fiberdb=# \d "Line";
Table "public.Line"
Column | Type
|
Modifiers
----------------------------+-----------------------------
+---------------------------------------------------------
LineName | character varying(50) | not
null
"PRI_Line" PRIMARY KEY, btree ("LineName")
As you can see, pretty straightforward.
But, in my code I'd like to search for all Fibers which belong to a
group of Lines. The Lines are chosen by the user , and I'd like to
filter these Fibers depending on some conditions (like FiberUsed =
True).
Because there might be a lot of branches for this search (as we add
options to the search engine, branches in the code will be added to),
I'd like to do the join seperately in the head of the function and
save the result of the join in some variable.
This variable should be used in the branches of my code. This allows
me to easily change the join conditions without changing the join in
10 branches of my code.
My current code is like this:
def _get_list_Lines_between_Sites(self, site1, site2,
LineDiscarded):
query = models.Session.query
(models.Line)
if site2 ==
None:
return query.filter(and_
(models.Line.LineDiscarded == LineDiscarded, or_
(models.Line.SiteLocationCodeA == site1,models.Line.SiteLocationCodeB
== site1)))
else:
return query.filter(and_
(models.Line.LineDiscarded == LineDiscarded, or_(and_
(models.Line.SiteLocationCodeA == site1,models.Line.SiteLocationCodeB
== site2),and_(models.Line.SiteLocationCodeA ==
site2,models.Line.SiteLocationCodeB == site1) )))
The "query = " seems to be pretty invalid, but although I've tried
about 10 alternatives (3 parameter for the join, using quotes, not
using quotes, etc), I can't get this to work.
Would anybody mind giving me a hand on this one?
Yours sincerely,
Boudewijn Ector
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