On 19 jan, 18:04, "Thiago F. Crepaldi" <togn...@gmail.com> wrote:
Absolutely not an answer to your question, but...
> below is the code required. I hope you can help me =)
>
#*****************************************************************************************************************************************************************
> # searchFeature
#*****************************************************************************************************************************************************************
> def searchFeature(request, view = None):
> if request.method == 'POST':
> form = SearchFeatureForm(request.POST)
> if form.is_valid():
> # Perform the query
>
> ftrQuery = Feature.objects.all().order_by('featureId',
> 'pk')
Since your going to filter this out, starting by querying all is
useless (thanks to querysets being lazy, it's at least _only_ useless.
Remember that Django has Q objects for building complex queries, and
that you can just collect Q objects in a list, then "or" or (like in
this case) "and" them together in just one pass.
>
> # Remove empty fields and start filtering
> if request.POST.__getitem__('featureId') != "":
First point : you should never directly access __magic_methods__ in
Python - they are here as implementation for operators. In this case,
you want:
if request.POST.get('featureId', '') != '':
Second point: since empty strings eval to false in a boolean context,
you don't have to explicitely compare them with the empty string. IOW:
if request.POST.get('featureId, ''):
> ftrQuery = ftrQuery.filter(featureId__contains =
> request.POST.__getitem__('featureId')).distinct()
Third point : you're doing the same access twice. Better to do it just
once:
featureId = request.POST.get('featureId, '')
if featureId:
# code here
While we're at it, attribute lookup is a somewhat costly operation in
Python, specially when the attribute resolves to a method. So if
you're going to heavily use the same method of the same object, it's
better to alias it to a local name:
get_from_post = request.POST.get
featureId = get_from_post('featureId, '')
if featureId:
# code here
While we're at it : your form object is supposed to give you access to
the validated (and possibly converted) data extracted from the
request. Is there any reason to not use this feature ?
Next point : you can pass dict objects to Queryset.filter(), (or to Q
objects) using the ** notation (cf the section of the official Python
tutorial about functions and named / keyword arguments). So you could
greatly simplify you code:
filters = [
# fieldname, lookup
("featureId", "featureId__contains"),
("name", "name__icontains")
("pf", "platform"),
("state", "state"),
("db", "drumbeat__pk"),
# etc
]
queries = []
add_q = queries.append
for fieldname, lookup in filters:
value = get_from_post(fieldname, '')
if value:
add_q(Q(**{lookup:value}))
# now "and" the Q objects:
filters = reduce(lambda q1, q1 : q1 & q2, filters)
# and do the query:
if filters:
queryset = Feature.objects.filter(filters)
else:
queryset = Feature.objects.all()
queryset = queryset.order_by('featureId', 'pk')
This can not apply to all your query construction (there are some
complex cases in it), but it should already help uncluttering it for
all the simple cases.
(snip)
> from datetime import date
Better to put import statements at the module's top-level.
> #Only way I could find to select with COUNT without
> writting the SQL code.
You might have a look at the example snippet for the 'extra' method of
querysets.
> if queryTeamSizeLow != '':
> for item in ftrQuery:
> if item.teammember_set.count() < int
> (queryTeamSizeLow):
Oh my. Pity this poor computer, and at least convert queryTeamSizeLow
to an int only once...
> ftrQuery = ftrQuery.exclude
> (featureId=item.featureId)
>
> if queryTeamSizeHigh != '':
> for item in ftrQuery:
> if item.teammember_set.count() > int
> (queryTeamSizeHigh):
> ftrQuery = ftrQuery.exclude
> (featureId=item.featureId)
Ok. Some things are better done building raw sql queries. Django's ORM
is here to help with the easy and boring 80%, not to replace SQL.
My 2 cents...
(snip)
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