django-queryset

问题 I'm trying to tweak an application that is suffering in speed department. Because of that, I've started converting all the for-loop statements to list comprehensions when possible. Currently, I'm working on a function that needs to iterate through a dictionary of Django querysets. The old code uses for-loop statement to iterate through this and it works fine. My code that uses list comprehension returns django querysets instead of my model object. Here is the code: def get_children(parent): #

问题 I'm trying to tweak an application that is suffering in speed department. Because of that, I've started converting all the for-loop statements to list comprehensions when possible. Currently, I'm working on a function that needs to iterate through a dictionary of Django querysets. The old code uses for-loop statement to iterate through this and it works fine. My code that uses list comprehension returns django querysets instead of my model object. Here is the code: def get_children(parent): #

问题 How can I order a Django QuerySet from a serializer field? Since the field is too complicated, I couldn't order the QuerySet using annotate and I cannot store the value in the model as well. Edit: Serializer class DrinkListModelSerializer(serializers.ModelSerializer): count_need = serializers.SerializerMethodField() url = drink_detail_url class Meta: model = Drink fields = [ 'name', 'count_need', 'thumbnail', 'url' ] def get_count_need(self, obj): drink_ingredient_qs = obj.ingredients.all()

问题 [ Update : software versions Python 2.7.2, Django 1.3.1] Can anyone explain this console code? FinishingStep has a ForeignKey to a quote object, but that's not really relevant. >>> fins = FinishingStep.objects.filter(quote=jq) >>> fins [<FinishingStep: Tabbing>, <FinishingStep: Collator>] So far so good, we have returned a QuerySet with two objects. But now the confusion. Both objects now appear to be the same: >>> fins[0] <FinishingStep: Collator> >>> fins[1] <FinishingStep: Collator>

问题 (Please let me know if this is completely absurd, that is probably a reason why I haven't found anything on this.) This story has two models Ranking and Artist , Ranking is generically related to Artist (object_id, content_type... the whole shebang). I have a list of objects returned by Ranking.objects.values_list() ordered by a certain field (in my case score ). So obviously, if I want to display a list of artists that were ranked, I'd want them in the same order. I've tried different

问题 Need a way for calls to User.objects.filter/get to only return User objects with is_active set to True. I tried to define a custom Manager and monkey patch it onto the User model, like this: class CustomUserManager(UserManager): def get_query_set(self): return super(CustomUserManager, self).get_query_set(). filter(is_active=True) User.objects = CustomUserManager() User.objects_all = UserManager() But, when I try to make a call to User.objects.get(), I get: AttributeError: 'NoneType' object

问题 how to use not like in django queries Model.objects.filter(keywords not like "null" or "undefined") select * from model where keywords not like "%undefined%" or keywords not like "%null%"; 回答1: use the exclude function and Q objects Model.objects.exclude(Q(keyword__contains='undefined') | Q(keyword__contains='null')) 来源： https://stackoverflow.com/questions/4193097/django-not-like-statement

问题 this is realted to my other question django-rest-framework, multitable model inheritance, ModelSerializers and nested serializers In django rest framework we can define nested model serializer like so class OtherModelSerializer(serializer.ModelSerializer): mybasemodel_set = MyBaseModelSerializer(many=True) class Meta: model = OtherModel when we create an OtherModelSerializer, the MyBaseModelSerializer is instantiated before __init__ is run. I believe this is the case because if I override the

问题 I have the following models: class Foo(models.Model): pass class Bar(models.Model): foo = models.ForeignKey(Foo) is_successful = models.BooleanField() I would like to get all foo objects with an annotation if all of the bar objects associated with foo object have is_successful as True So far my queryset is: foos = Foo.objects.all().annotate(all_successful=Min('bar__is_successful')) The idea for the all_successful annotation is that if the minimum value of all is_successful rows is 1, then all

问题 I have a model with the a field data of type JSONField from django.contrib.postgres.fields . The json structure is like so: {'aa': 1, 'bb': 2, 'cc': 4} I want to aggregate the sums of the aa and cc keys - so in this case, it will be 5. Also - i cannot promise that either aa or cc will be in the json. Is this possible? If so - i want to order by the aggregated data. Example: id: 1, data = {'aa': 1, 'bb': 2, 'cc':4} id: 2, data = {'aa': 3, 'bb': 2} id: 3, data = {'cc': 7} id: 4, data = {'bb': 7