How to update two models with one form? - django

Question

I want to be able to have a user update two models with one submit button. The first model will house all of the book titles (unique) and pages that users submit. The other will show which users submitted which books.
Ideally, I'd like to do something like this:
if request.method == "POST":
form = AddBookForm(request.POST)
if form.is_valid():
books = form.save(commit=False)
ub = UserBooks()
books.book_title = form.cleaned_data['book_title']
books.book_total_pages = form.cleaned_data['book_total_pages']
ub.user = request.user
ub.book_title = form.cleaned_data['book_title']
ub.save()
books.save()
return redirect('new_book')
But that's giving me the error:
Cannot assign "'Some Book Title'": "UserBooks.book_title" must be a
"Books" instance.
What would be the best way to update two models with one form?
Here are the other files.
models.py
class Books(models.Model):
created = models.DateTimeField(auto_now_add=True, editable=False)
last_updated = models.DateTimeField(auto_now=True, editable=False)
book_title = models.CharField(max_length=100, unique=True)
book_total_pages = models.IntegerField()
class Meta:
ordering = ('-created',)
def __str__(self):
return '{0}'.format(self.book_title)
class UserBooks(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE, null=False, blank=False)
book_title = models.ForeignKey(Books, on_delete=models.CASCADE, null=False, blank=False)
views.py
def new_book(request):
user = request.user
if request.method == "POST":
form = AddBookForm(request.POST)
if form.is_valid():
books = form.save(commit=False)
books.book_title = form.cleaned_data['book_title']
books.book_total_pages = form.cleaned_data['book_total_pages']
books.save()
return redirect('new_book')
else:
form = AddBookForm()
return render(request, 'main/addanewbook.html', {
'form': form,
'allBooks': allBooks,
'userbooks': userbooks,
})
forms.py
class AddBookForm(forms.ModelForm):
class Meta:
model = Books
fields = ('book_title', 'book_total_pages')

Answer 1

you need to change a bit in the view
if form.is_valid():
books = form.save(commit=False)
ub = UserBooks()
books.book_title = form.cleaned_data['book_title']
books.book_total_pages = form.cleaned_data['book_total_pages']
books = books.save()
ub.user = request.user
ub.book_title = books
ub.save()
return redirect('new_book')
this will do it