Django related_name not querying the data in template

Question

I have two models, Transaction and Subscription. Transaction has a FK to Subscription with the related name="subscription_transaction". I am trying to query the transaction.amount on a SubscriptionDetailView. Why is my template query not working.

Neither work

subscription_detail.html

<td  class="text-dark ">{{ subscription.subscription_transaction.timestamp.all }}</td
<td  class="text-dark"> {{ subscription.subscription_transaction.amount }}</td>`

models.py

class Subscription(models.Model):
    id = models.CharField(max_length=36, unique=True, default=uuid.uuid4, primary_key=True, editable=False)
    user_membership = models.ForeignKey(UserMembership, on_delete=models.CASCADE)
    stripe_subscription_id = models.CharField(max_length=40)
    active = models.BooleanField(default=True)

    def __str__(self):
        return self.user_membership.user.username

    @property
    def get_created_date(self):
        subscription = stripe.Subscription.retrieve(self.stripe_subscription_id)
        return datetime.fromtimestamp(subscription.created)

    @property
    def get_next_billing_date(self):
        subscription = stripe.Subscription.retrieve(self.stripe_subscription_id)
        return datetime.fromtimestamp(subscription.current_period_end)


class Transaction(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name="user_transaction")
    order_id = models.CharField(max_length=36, unique=True, default=uuid.uuid4, primary_key=True, editable=False)
    subscription = models.ForeignKey(Subscription, on_delete=models.SET_NULL, null=True, blank=True, related_name="subscription_transaction")
    amount = models.DecimalField(max_digits=100, decimal_places=2)
    success = models.BooleanField(default=True)
    timestamp = models.DateTimeField(auto_now_add=True, auto_now=False)

Answer 1

Since subscription.subscription_transaction is a RelatedManager object, you can get all transactions of the subscription using .all .

Example :

{% for transaction in subscription.subscription_transaction.all %}
    Timestamp: {{ transaction.timestamp }}, 
    Amount: {{ transaction.amount }}
{% endfor %}

Answer 2

Notice that Transaction has a ForeignKey to Subscription . That's a one to many relation: Each Transaction row can have up to one Subscription however each Subscription can be related with many Transactions .

Following this you should now understand that you are able to use the direct relation betwen Transaction and Subscription (ie from a Transaction instance) directly, ie you can do something like transaction.subscription.active sincec each transaction will have one subscription. However, to use the reverse relation (ie from Subscription ) you need to properly use the related object manager to enumerate all possible transactions the subscription may have. Remember that Django auto-names the reverse relation object something_set (in your case instead of subscription_transaction you'd have a transaction_set attribute to the Subscription instance); there's a reason for that: To remember that the reverse relation of a foreign key is a set of objects!

Thus, if you change your template code to something like:

{% for tr in subscription.subscription_transaction.all %}
  {{ tr.timestamp }}
  {{ tr.amount }}
{% endfor %}

it will output all the transactions of the subscription.