This seems so blatant that it couldn't really be a bug without someone
noticing. Django 1.2
qs = Apt.objects.filter(list_on_web=True,is_available=True)
# FastAdderStatus has Apt and Service as fk
qs = qs.filter(fastadderstatus__service=self.service)
# later on here's another filter on the same table
qs = qs.filter(fastadderstatus__running_status__in= (2, 3, 4))
produces this:
SELECT U0."id" FROM "nsproperties_apt" U0 INNER JOIN
"fastadder_fastadderstatus" U1 ON (U0."id" = U1."apt_id") INNER JOIN
"fastadder_fastadderstatus" U3 ON (U0."id" = U3."apt_id") WHERE
(U0."list_on_web" = True AND U0."is_available" = True AND
U1."service_id" = 4 AND U3."running_status" IN (2, 3, 4))
Note that it joins the same table twice, and the Apt is not returning
distinct. Postgres is not liking the query.
count: 2837
[<Apt: Property #12297>, <Apt: Property #12297>, <Apt: Property
#12297>, <Apt: Property #12304>, <Apt: Property #12304>, <Apt:
Property #12304>, <Apt: Property #12305>, <Apt: Property #12305>,
<Apt: Property #12305>, <Apt: Property #12308>, <Apt: Property
#12308>, <Apt: Property #12308>, <Apt: Property #12309>, <Apt:
Property #12309>, <Apt: Property #12309>, <Apt: Property #12311>,
<Apt: Property #12311>, <Apt: Property #12311>, <Apt: Property
#12314>, <Apt: Property #12314>, '...(remaining elements
truncated)...']
what it should say (manually fixed) :
SELECT U0."id" FROM "nsproperties_apt" U0 INNER JOIN
"fastadder_fastadderstatus" U1 ON (U0."id" = U1."apt_id") WHERE
(U0."list_on_web" = True AND U0."is_available" = True AND
U1."service_id" = 4 AND U1."running_status" IN (2, 3, 4))
count: 611, no dups
My solution:
params = {}
if self.service:
params['fastadderstatus__service'] = self.service
if self.agent:
params['agents'] = self.agent
if self.status:
params.update(
FastAdderStatus.objects.filter_params_for_status(self.status,'fastadderstatus')
)
# a single call to filter
qs = qs.filter(**params)
which avoids the (?) bug and also is vastly more efficient.
Having just stepped through with the debugger and seen how much work
is involved with .filter I am in future going to avoid any multiple
calls to filter. Its better to pass around dicts.
SELECT U0."id" FROM "nsproperties_apt" U0 INNER JOIN
"fastadder_fastadderstatus" U1 ON (U0."id" = U1."apt_id") INNER JOIN
"nsproperties_apt_agents" U2 ON (U0."id" = U2."apt_id") WHERE
(U0."is_available" = True AND U0."list_on_web" = True AND
U1."running_status" IN (2, 3, 4) AND U2."agent_id" = 175 AND
U1."service_id" = 4 )
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