mmh, cant really grasp what u want to do.
what are Line.* attributes?
.filter does and(), so this can be simplified:
q = query(Line).filter( models.Line.LineDiscarded == LineDiscarded )
if ...:
return q.filter( sites...)
else:
return q.filter( sites...)
On Monday 19 January 2009 23:28:55 boudewijnector wrote:
> 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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