Django field with multiple values and multiple owners

Question

I am struggling with the concept with a very join-ed relationship. I want to have something like:

class Category(models.Model):
    name = models.CharField(max_length=128, unique=True)
    descriptions = models.Listfield? #or something like this

class Descriptions(models.Model):
    name = models.CharField(max_length=128, unique=True)
    categories = models.Listfield? #or something like this

the idea is that categories will have descriptions that you can click that will give you a list of categories with that description, and vice versa. So if categories were like [Elephant, Truck, Tree] and descriptions were like [Heavy, Trunk], I'd want it set up so Elephant.descriptions = [Heavy, Trunk] and Heavy.categories = [Elephant, Truck]

Answer 1

You could use a ManyToManyField since it's a many to many relationship (one category can be associated with many descriptions and one description can be associated with many categories

class Category(models.Model):
    name = models.CharField(max_length=128, unique=True)


class Description(models.Model):
    name = models.CharField(max_length=128, unique=True)
    categories = models.ManyToManyField(Category, blank=True)

With this method you only need to add the ManyToManyField in one of the models, either Descriptions or Categories.

you then could do the following:

new_cat = Category(name = 'cat1')
new_cat.save()
new_desc = Description(name = 'desc1')
new_desc.save()
new_desc.categories.add(new_cat)

and they would be associated with each other, with no need for a ManyToManyField in the Category model

you can then access all the categories associated with new_desc with:

new_desc.categories.all()

or

new_cat.description_set.all()

for all of the descriptions associated with new_cat.

It will return a QuerySet though, not a list

More info on ManyToManyField:

https://docs.djangoproject.com/en/1.8/topics/db/examples/many_to_many/