django-queryset

问题 This question already has answers here : A QuerySet by aggregate field value (3 answers) Closed 5 years ago . I have a handful of records that I would like to sort based on a computed value. Got the answer over here... like so: sorted(Profile.objects.all(), key=lambda p: p.reputation) on a Profile class like this: class Profile(models.Model): ... @property def reputation(self): ... Unfortunately the generic view is expecting a queryset object and throws an error if I give it a list. Is there

问题 Here's what my model structure looks like: class Visitor(models.Model): id = models.AutoField(primary_key=True) class Session(models.Model): id = models.AutoField(primary_key=True) visit = models.ForeignKey(Visitor) sequence_no = models.IntegerField(null=False) class Track(models.Model): id = models.AutoField(primary_key=True) session = models.ForeignKey(Session) action = models.ForeignKey(Action) when = models.DateTimeField(null=False, auto_now_add=True) sequence_no = models.IntegerField

问题 Here's what my model structure looks like: class Visitor(models.Model): id = models.AutoField(primary_key=True) class Session(models.Model): id = models.AutoField(primary_key=True) visit = models.ForeignKey(Visitor) sequence_no = models.IntegerField(null=False) class Track(models.Model): id = models.AutoField(primary_key=True) session = models.ForeignKey(Session) action = models.ForeignKey(Action) when = models.DateTimeField(null=False, auto_now_add=True) sequence_no = models.IntegerField

问题 Follow up question to this one: Django merge 2 querysets in staggered/alternating fashion? I'm wondering is there an efficient way to avoid duplicates in the result? i.e. the generators will only return items we have not seen before. 来源： https://stackoverflow.com/questions/45834009/django-merge-2-querysets-in-staggered-alternating-fashion-without-duplicates

问题 I have a model with field: class Product(models.Model): subproducts = models.ManyToManyField("self", blank=True) I need to overwrite admin's field queryset, to display only that objects that don't belong to any m2m relation. I have no idea how to get them. So if I have: product1, product2, product3, product4. product1 contains in subproducts: product2 I need a query that will get, in that situation, product3 and product4 Any idea how to get that? 回答1: I think that did the trick: Product

问题 I have a multiple choice field with a foreign key. I want to save which keeper was attending a training session and I want to list all keepers as a multiple choice field. class AddAttendance(forms.ModelForm): attendanceKeeper = Attendance.objects.only("keeper","present").all() keeperValues = Attendance.objects.values_list("keeper__id", flat=True).distinct() keeper = forms.ModelMultipleChoiceField(widget=forms.widgets.CheckboxSelectMultiple, queryset=Keeper.objects.filter(id__in=keeperValues,

问题 I have a Session model like this: class Session(models.Model): user = models.ForeignKey(User, null=True, blank=True, on_delete=models.CASCADE, related_name="sessions") flavor = models.ForeignKey(Flavor, null=True, blank=True, on_delete=models.CASCADE, related_name="sessions") .... And I'm trying to run a query: sessions = Session.objects.all().values('flavor__pk', 'user__pk').distinct() But when I then print the sessions object I get this: <QuerySet [{'user__pk': 14544, 'flavor__pk': 1}, {

问题 I have a model for a company. Then I have a base model for company posts. It contains common posts attributes. An attribute is the company that publishes the posts. It refers to the Company model with a ForeignKey. Finally I have a child model (based on the CompanyPost base model) for posts of type A: class Company(models.Model): name = models.CharField(...) ... class CompanyPost(models.Model): company = models.ForeignKey(Company,...) ... class PostA(CompanyPost): name = ... In a template I

问题 I need to check a table from a remote db and update another table in my db. The models have same fields but checking with difference method will return an error: qs1 get the data from one postgresql db qs2 get the data from one mysql db qs1 = (Local.objects .values_list('ref') ) qs2 = (Remote.objects .filter() .values_list('ref')) >>> qs1.difference(qs1, qs2) DatabaseError: intersection not supported on this database backend. 回答1: I'm not exactly sure what you think your code is doind. qs1

问题 I have created an app here people can upload 'csv' files of their items details to the server, and then perform various opertaions upon it. But, because every item has it's own unique ID, whenever a csv is uploaded, there is no way to figure out which item-batch was uploaded last. Upload function This is my function in views.py importing the data in the Itembatch model: @method_decorator([login_required, teacher_required], name='dispatch') class UploadedItems(ListView): model = ItemBatch