Django movie and director relation. Movie is not attached to the director

Question

I'm making a model, consisting of a movie and a director. When I create a movie, I want the movie to be automatically owned by the director I selected but it's not working.

class Movie(models.Model):
    name = models.CharField(max_length=100)
    category = models.CharField(max_length=100)
    imdb = models.DecimalField(max_digits=2, decimal_places=1)     
    director = models.ForeignKey('Director', on_delete=models.DO_NOTHING)

    class Meta:
        verbose_name_plural = 'Movies'

    def __str__(self):
        return self.name


class Director(models.Model):
    name = models.CharField(max_length=150)
    movies = models.ManyToManyField(Movie, related_name='movies', blank=True)

    class Meta:
        verbose_name_plural = 'Directors'

    def __str__(self):
        return self.name
    

I am creating a new movie using django-admin page. for instance;django-admin creating movie

However the movie is not automatically added to the director. Director

I also want a movie to belong to only one director. How can I do these. I will be very glad if you can help me. Thanks in advance

Answer 1

That's already the case without any need for an extra relation. Indeed, you define this as:

class Movie(models.Model):
    name = models.CharField(max_length=100)
    category = models.CharField(max_length=100)
    imdb = models.DecimalField(max_digits=2, decimal_places=1)
    director = models.ForeignKey(
        'Director', on_delete=models.DO_NOTHING, related_name='movies'
    )

    class Meta:
        verbose_name_plural = 'Movies'

    def __str__(self):
        return self.name


class Director(models.Model):
    name = models.CharField(max_length=150)

    class Meta:
        verbose_name_plural = 'Directors'

    def __str__(self):
        return self.name

If you then assign a director D1 to a move M1, you can query the movies of the director with:

D1.movies.all()

In the modeladmin you can also display the movies when editing a Director through an inline, for example a TabularInline ^[Django-doc]:

from django.contrib import admin


class MovieInline(admin.TabularInline):
    model = Movie


@admin.register(Director)
class DirectorAdmin(admin.ModelAdmin):
    # …
    inlines = [
        MovieInline,
    ]