Question

I have django models with a manytomany connection with a through class:

class userProfile(models.Model):
    boughtCoupons = models.ManyToManyField(Coupon, through='UserCoupons')

class UserCoupons(models.Model):
    user = models.ForeignKey(userProfile)
    coupon = models.ForeignKey(Coupon)
    date = models.DateField()


class Coupon(models.Model):
    name = models.CharField(max_length=10)

I know how I can get each of them individually using and ID or something to filter.

But, I need to get the Through table’s value with all the user’s details (profile).

So how can I do something like a JOIN, and get a UserCoupons + userProfile pair in a single query ? ( So I can get the matching user profile without an extra query ?)

Answer 1

You can query directly on UserCoupons and use select_related() to fetch also the related objects in one query:

UserCoupons.objects.select_related().filter(**your_filters)

Note that select_related() doesn’t work “backwards”. That’s why you need to use a manager of the class that defines the ForeignKey to make it work (UserCoupons in this case).