Styjun

First of all, my apologize for mistakes in English.

I have three Models: Books (General Model), BookInfo (Information about book), Location (Position in Library) with Foreign Key.

models.py

class Location(models.Model):
 room = models.PositiveIntegerField()
 bookcase = models.PositiveIntegerField()
 shelf = models.PositiveIntegerField()


class BookInfo(models.Model):
 title = models.CharField(max_length=120)
 author = models.CharField(max_length=150)
 published = models.CharField(max_length=4)
 position = models.ForeignKey(Location, on_delete = models.CASCADE, related_name = 'position_information')

 def __str__(self):
 return self.title
 class Meta:
 ordering = ['-id']
 unique_together = ['title', 'author']


class Books(models.Model):

 ON_HANDS = 1
 IN_LIBRARY = 0
 ALARM = -1

 STATUS = (
 (ON_HANDS, 'The book is on hands'),
 (IN_LIBRARY, 'The book is in library'),
 (ALARM, 'Need to return the book')
 )

 book = models.ForeignKey('BookInfo', on_delete = models.CASCADE, related_name = 'book_information')
 date_of_issue = models.DateField(blank= True, default=timezone.now)
 date_of_return = models.DateField(blank= True, default=date.today() + timedelta(days=14))
 status_of_book = models.IntegerField(choices = STATUS, default = 0)

 def __str__(self):
 return self.book.title

 class Meta:
 ordering = ['-id']

forms.py

 class BookFormUpdate(forms.ModelForm):
 class Meta:
 model = Books

 fields = ['book','date_of_issue','date_of_return','status_of_book']
 widgets = 
 'date_of_issue': forms.DateInput(format=('%Y-%m-%d'), attrs='class':'form-control', 'placeholder':'Select a date', 'type':'date'),
 'date_of_return': forms.DateInput(format=('%Y-%m-%d'), attrs='class':'form-control', 'placeholder':'Select a date', 'type':'date')
 

When I use Update Form for Books and change status of book to 1 or -1, I want automatically change the position of Book to (0,0,0). I overwrite my UpdateView but got some problem.

views.py

class MainUpdate(UpdateView): 
 model = Books
 template_name = 'core/detail.html'
 form = BookFormUpdate

 def form_valid(self, form):
 form.save()
 categories = get_object_or_404(self.model, pk=self.kwargs.get('pk'))
 stat = form.cleaned_data['status_of_book']
 if stat == 1 or stat == -1:
 book_id = categories.book.id
 BookInfo.objects.filter(id=book_id).update(position=Location.objects.get(id=32))
 return redirect('/books-info/')

For updating the postion I used Location.objects.get(id=32) (id=32 corresponds to position (0,0,0)).
Is there another solution or better way without overwriting the UpdateView to change the position automatically?

I was trying to use such code:

# Not work
BookInfo.objects.filter(id=book_id).update(position__room=0,position__bookcase=0,position__shelf=0)

# Not work
BookInfo.objects.select_related().filter(id=book_id).update(position__room=0,position__bookcase=0,position__shelf=0)

# Not work
test = BookInfo.objects.get(id=book_id)
test.position__room=0
test.position__bookcase=0
test.position__shelf=0
test.save(update_fields=['position__room','position__bookcase','position__shelf'])

Thanks for advise and help