Ordering many-to-many relations in Django models

Question

Suppose you have a many-to-many relation in a Django model, such as:

class GroceryList(models.Model):
    items = models.ManyToManyField(GroceryItem, related         


        

Answer 1

You can use the intermediate table using through and add the ordered field in that table.

class GroceryList(models.Model):
    items = models.ManyToManyField(GroceryItem, related_name='in_lists', 
            through='Order')

class GroceryItem(models.Model):
    name = models.CharField(unique=True)

class Order(models.Model):
    number = models.PositiveIntegerField()
    gl = models.ForeignKey(GroceryList)
    gi = models.ForeignKey(GroceryItem)

So instead of doing grocerylist.items.add(groceryitem) you can do

#for groceryitem1 as 1st item in grocerylist1
Order.objects.create(gl=grocerylist1, gi=groceryitem1, number=1)

#for groceryitem1 as 10th item in grocerylist2
Order.objects.create(gl=grocerylist2, gi=groceryitem1, number=10)