Hi Germano, When you use "ManyToMany", you're saying "any book can have any chapter and vice versa". That's obviously what you don't want. What you want is "A book has a closed set of chapters". This is done by thinking a bit on the other way with Django: Instead of saying "There is a list of chapters of this book", you say "The chapter belongs to a single book" with a foreign key:
class Book(models.Model): title = models.CharField(max_length=250) class Chapters(models.Model): title = models.CharField(max_length=250) text = models.TextField() book = models.ForeignKey(Book) Now a chapter can belong only to a book. On Thu, Aug 9, 2018 at 4:34 PM, Germano Carella <[email protected]> wrote: > Hi, > I'm Germano from Italy. I'm new of django. > Probably this discussion has many many examples, but I can't find > my situation. > I have two models, Book and Chapters. > These are simple models, I need them only for educational purpose. > > class Book(models.Model): > title=models.CharField(max_length=250) > chapters = models.ManyToManyField('Chapters') > > class Chapters(models.Model): > title_of_chapter = models.CharField(max_length=250) > text=models.TextField() > > Now, in admin interface I can add chapters on a new book and it works fine. > So, whdn I try to add a second book I can see chapters of book I added > previously. > > When I add a new book I want see only chapter of this book. List must be > empty if I'm adding a new book. > It's very simple, but I can't find a way to make it working. > > I tried somethings, such as > chapters= models.ManyToManyField('Chapters',limit_choices_to=Q(' > book__title'=title)) > But this not works. > I know Chapters has book_set, that is the set of references for a chapter. > > There is a way to make it working? > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/django-users. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/django-users/2f104d64-50f4-433b-a764-be29d9a77f0c%40googlegroups.com > <https://groups.google.com/d/msgid/django-users/2f104d64-50f4-433b-a764-be29d9a77f0c%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- *Julio Biason*, Sofware Engineer *AZION* | Deliver. Accelerate. Protect. Office: +55 51 3083 8101 <callto:+555130838101> | Mobile: +55 51 <callto:+5551996209291>*99907 0554* -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CAEM7gE0rAfJPYbgKxgHCRYwVuAEBGQrz5X2WxOJdOW6mG%3DzK3Q%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
