I'm trying to order a queryset by the CharField 'name', but I want to exclude the 'Other' entry and add it as a last option for the user to choose...
self.fields["acquisition"].queryset = AcquisitionChannel.objects.exclude(name = "Other").order_by('name')
The above is obviously not good because it excludes the 'Other'...
Could it be done in Django? or I must use Javascript?
Thanks!
To manually add objects to a QuerySet, try _result_cache:
other = AcquisitionChannel.objects.get(name="Other")
objs = AcquisitionChannel.objects.exclude(name="Other").order_by("name")
len(objs) #hit the db to evaluate the queryset.
objs = objs._result_cache.append(other)
self.fields["acquisition"].queryset = objs
Quick and simple: add an order column that takes a special value using extra():
self.fields["acquisition"].queryset = (
AcquisitionChannel.objects
.extra(select={'order': '(CASE name WHEN %s THEN 1 ELSE 0 END)'},
select_params=['Other'],
order_by=['order', 'name']))
Using params, this method works on any DB (that supports CASE).
It's something like:
def get_choices():
choices = AcquisitionChannel.objects.exclude(name = "Other").order_by('name').values_list('value_column', 'text_column')
other = AcquisitionChannel.objects.filter(name = "Other").values_list('value_column', 'text_column')
choices = list(choices)
other = list(other)
return choices + other
then:
acquisition = forms.ChoiceField(choices=get_choices())
Related
I have the following models:
## Tags for issues
class issueTags(models.Model):
name = models.CharField(max_length=400)
class issues(models.Model):
tags = models.ManyToManyField(issueTags,blank = True)
In my view I get an array from some client side JavaScript i.e.
(Pdb) array_data = request.POST['arr']
(Pdb) array_data
'["2","3"]'
How should I filter my issues object to find all issues which match all tags in the array? (the 2,3 are the ID values for tag__id.
If there is a better way to arrange the objects that would also work so I can search in this fashion.
At the time of writing this, the existing answers are either incorrect (e.g. filtering matching all Issues that have any of the specified tags and the correct tag count) or inefficient (e.g. attaching filters in a loop).
For the following models:
class IssueTag(models.Model):
name = models.CharField(max_length=400, blank=True)
class Issue(models.Model):
label = models.CharField(max_length=50, blank=True)
tags = models.ManyToManyField(IssueTag, related_name='issues')
I suggest using Django Annotation in conjunction with a filter like so:
from django.db.models import Count, Q
tags_to_match = ['tag1', 'tag2']
issues_containing_all_tags = Issue.objects \
.annotate(num_correct_tags=Count('tags',
filter=Q(tags__name__in=tags_to_match))) \
.filter(num_correct_tags=2)
to get all Issues that have all required tags (but may have additional tags, as is required in the question).
This will produce the following SQL query, that resolves all tag matching in a single IN clause:
SELECT "my_app_issue"."id", "my_app_issue"."label",
COUNT("my_app_issue_tags"."issuetag_id")
FILTER (WHERE "my_app_issuetag"."name" IN ('tag1', 'tag2'))
AS "num_correct_tags"
FROM "my_app_issue"
LEFT OUTER JOIN "my_app_issue_tags" ON ("my_app_issue"."id" = "my_app_issue_tags"."issue_id")
LEFT OUTER JOIN "my_app_issuetag" ON ("my_app_issue_tags"."issuetag_id" = "my_app_issuetag"."id")
GROUP BY "my_app_issue"."id", "my_app_issue"."label"
HAVING COUNT("my_app_issue_tags"."issuetag_id")
FILTER (WHERE ("my_app_issuetag"."name" IN ('tag1', 'tag2'))) = 2;
args=('tag1', 'tag2', 'tag1', 'tag2', 2)
I haven't tested this, but I think you could do the following:
from django.db.models import Q
array_data = array_data.split(',')
issues.objects.filter(
tags__in=array_data,
).exclude(
# Exclude any that aren't in array_data
~Q(tags__in=array_data)
).annotate(
matches=Count(tags, distinct=True)
).filter(
# Make sure the number found is right.
matches=len(array_data)
)
FYI, you should be using Issue, IssueTag for your model names to follow Django's naming pattern.
It isn't most elegant solution or pythonic but I ended up just looping around the resulting filter.
def filter_on_category(issue_object,array_of_tags):
#keep filtering to make an and
i = 0
current_filter = issue_object
while (i < (len(array_of_tags))):
#lets filter again
current_filter=current_filter.filter(tags__id__in=array_of_tags[i])
i=i+1
return current_filter
Django field lookups argument (__) for many-to-many fields needs list argument. I have created a dummy list for each array element of IssueTags and pass it to lookups argument and it works as expected.
Let you have this models:
class IssueTags(models.Model):
name = models.CharField(max_length=400)
class Issues(models.Model):
tags = models.ManyToManyField(IssueTags,blank = True)
You want to get Issues which contains all of these IssueTags = ["1","2","3"]
issue_tags_array = ["1","2","3"]
#First initialize queryset
queryset = Issues.objects.all()
i = 0
while i < len(issue_tags_array):
#dummy issue_tag list
issue_tag = [issue_tags_array[i]]
#lets filter again
queryset = queryset.filter(tags__id__in=issue_tag)
i=i+1
return queryset
My models are:
models.User:
id = pk
username = text
models.Offer
id = pk
description = text
publicationDate = Date
user = Fk(User)
my serializer is:
class UserOfferSerializer(ModelSerializer):
offers = OfferSerializerAll(many=True, read_only=True)
class Meta:
model = User
fields = ('id', 'username', 'offers')
I am trying to apply more than one filter on the queryset:
users = users.filter(offers__publicationDate__range=[startdate, enddate]). prefetch_related(Prefetch('offers', queryset=Offer.objects.filter(
publicationDate__range=[startdate, enddate]))).distinct()
then
users = users.filter(offers__description__icontains=sometext).prefetch_related(Prefetch('offers', queryset=Offer.objects.filter(description__icontains=sometext))).distinct()
First one works fine and the other one throws the following exception:
ValueError: 'offers' lookup was already seen with a different queryset. You may need to adjust the ordering of your lookups.
Update:
My current code is:
if (offerBeginDate != None and offerEndDate != None):
b = offerBeginDate.split('-')
e = offerEndDate.split('-')
startdate = datetime.date(int(b[0]), int(b[1]), int(b[2]))
enddate = datetime.date(int(e[0]), int(e[1]), int(e[2]))
users = users.filter(offers__publicationDate__range=[startdate, enddate])
offers = offers.filter(publicationDate__range=[startdate, enddate])
if (descriptionText != None):
users = users.filter(offers__functionDescription__icontains=descriptionText.strip())
offers = offers.filter(functionDescription__icontains=descriptionText.strip())
users = users.prefetch_related('offers', Prefetch(queryset=offers))
Any help? Thank you all :)))
You can use to_attr argument of Prefetch object to prefetch additional queryset:
users = users.filter(offers__description__icontains=sometext).prefetch_related(
Prefetch('offers', queryset=Offer.objects.filter(
publicationDate__range=[startdate, enddate]), to_attr='date_offers'),
Prefetch('offers', queryset=Offer.objects.filter(description__icontains=sometext), to_attr='description_offers')).distinct()
UPD
If you need dynamically add filters to prefetched queryset you can define it separately like this:
if some_case:
users = users.filter(offers__description__icontains=sometext)
offers=Offer.objects.filter(description__icontains=sometext)
if some_case_2:
users = users.filter(**conditions)
offers = offers.filter(**conditions)
users = users.prefetch_related(Prefetch('offers', queryset=offers))
Now each user in users queryset will have two attributes: user.date_offers and user.description_offers.
I'm stuck on a seemingly simple issue. I want to do a different queryset if sold_data is empty. Is there an effective way to do this? Or do I need to use a for loop and loop over all the listing objects and check each one?
class Listing(models.Model):
list_price = models.IntegerField()
sold_price = models.IntegerField(null=True, blank=True)
... other fields
data = Listing.objects.filter(...) # Note: I had already made other queries
if sold_price == None:
data = data.filter(list_price__gte=1)
else:
data = data.filter(sold_price__gte=1)
You can do it using Q object.
from django.db.models import Q
# your filtered queryset is in 'data' varibale
data.filter(Q(sold_price__isnull=False, sold_price__gte=1) | Q(sold_price__isnull=True, list_price__gte=1))
if you wanna check if an object is None use the is operator
I'm not sure if I did understand your question here is what I get : you wanna filter list_price if the data contains an object with empty value else filter sold_price
You can try this
if data.filter(sold_price__isnull=True).exists():
data = data.filter(list_price__gte=1)
else:
data = data.filter(sold_price__gte=1)
I have this url after you hit the search button:
127.0.0.1:8000/results/?name=blab&city=bla&km=12
my view:
def search(request):
name = request.GET.get('name')
city = request.GET.get('city')
km = request.GET.get('km')
if name!="" and name != None:
locations = Location.objects.filter(name__istartswith=name)
return render_to_response("result-page.html",{'locations':locations},context_instance=RequestContext(request))
if city!="" and city != None:
locations = Location.objects.filter(city__istartswith=city)
return render_to_response("result-page.html",{'locations':locations},context_instance=RequestContext(request))
but now, if i look for both name and city, it is giving ony the results search after name. e.g. the first paramater. second one is not being taken.
what is the best logic for this? i also want to able to sort the search result. can you please give me some hints how to this kind of things in clean logic.
thanks
You are returning on the first if, if you want to filter on either or both or no parameters try using one QuerySet with dynamic filters e.g. something like
search_kwargs = {}
if request.GET.get('name'):
search_kwargs['name__istartswith'] = request.GET.get('name')
if request.GET.get('city'):
search_kwargs['city__istartswith'] = request.GET.get('city')
locations = Location.objects.filter(**search_kwargs)
return render_to_response("result-page.html",{'locations':locations},context_instance=RequestContext(request))
or even something like
filter_fields = ['city','name']
for f in filter_fields:
if f in request.GET:
search_kwargs['%s__istartswith' % f] = request.GET.get(f)
Why is Django executing statements such as this:
SELECT (1) AS [a] FROM [my_table]
WHERE ([my_table].[id] = ?
AND NOT ([my_table].[id] = ? )) (1, 1)
This happens when calling is_valid() on a formset created the following way:
MyFormSet = modelformset_factory(Table, fields=['my_field'], extra=0)
my_form_set = MyFormSet(request.POST,
queryset=Table.objects.all())
where Table and MyForm are as simple as, say:
class Table(models.Model):
my_field = models.CharField(max_length=10)
class MyForm(forms.ModelForm):
class Meta:
model = Table
Hint: I looked at the call stack and the code responsible for it (in django/forms/models.py) is below:
def _perform_unique_checks(self, unique_checks):
import pdb; pdb.set_trace()
bad_fields = set()
form_errors = []
for unique_check in unique_checks:
# Try to look up an existing object with the same values as this
# object's values for all the unique field.
lookup_kwargs = {}
for field_name in unique_check:
lookup_value = self.cleaned_data[field_name]
# ModelChoiceField will return an object instance rather than
# a raw primary key value, so convert it to a pk value before
# using it in a lookup.
if isinstance(self.fields[field_name], ModelChoiceField):
lookup_value = lookup_value.pk
lookup_kwargs[str(field_name)] = lookup_value
qs = self.instance.__class__._default_manager.filter(**lookup_kwargs)
# Exclude the current object from the query if we are editing an
# instance (as opposed to creating a new one)
if self.instance.pk is not None:
qs = qs.exclude(pk=self.instance.pk)
Basically the pk is both included for the uniqueness check and excluded. Looks like Django can be smarter and avoid such inefficiency.
I haven't looked at it in detail, but I think you are right that Django could shortcut this query. Please file a ticket at http://code.djangoproject.com/.
Looks like this has been fixed already in trunk (by adding new functionality that also fixes this particular problem)