Implement ApplicationFeeRefund model

Closes dj-stripe#97

HISTORY.rst

@@ -17,8 +17,14 @@ History
   This includes ``date``, ``destination_type`` (``type``), ``failure_code``,
   ``failure_message``, ``statement_descriptor`` and ``status``.
 - Fixed IntegrityError when ``REMOTE_ADDR`` is missing (#640).
-- New models: ``BalanceTransaction``, ``CountrySpec``, ``SubscriptionItem``,
-  ``TransferReversal``, ``UsageRecord``
+- New models:
+  - ``ApplicationFee``
+  - ``ApplicationFeeRefund``
+  - ``BalanceTransaction``
+  - ``CountrySpec``
+  - ``SubscriptionItem``
+  - ``TransferReversal``
+  - ``UsageRecord``
 - The ``fee`` and ``fee_details`` attributes of both the ``Charge`` and
   ``Transfer`` objects are no longer stored in the database. Instead, they
   access their respective new ``balance_transaction`` foreign key.

djstripe/migrations/0002_auto_20180627_1121.py

@@ -301,6 +301,26 @@ class Migration(migrations.Migration):
                 "abstract": False,
             },
         ),
+        migrations.CreateModel(
+            name="ApplicationFeeRefund",
+            fields=[
+                ("djstripe_id", models.BigAutoField(primary_key=True, serialize=False, verbose_name="ID")),
+                ("id", djstripe.fields.StripeIdField(max_length=255, unique=True)),
+                ("livemode", models.NullBooleanField(default=None, help_text="Null here indicates that the livemode status is unknown or was previously unrecorded. Otherwise, this field indicates whether this record comes from Stripe test mode or live mode operation.")),
+                ("created", djstripe.fields.StripeDateTimeField(blank=True, help_text="The datetime this object was created in stripe.", null=True)),
+                ("metadata", djstripe.fields.JSONField(blank=True, help_text="A set of key/value pairs that you can attach to an object. It can be useful for storing additional information about an object in a structured format.", null=True)),
+                ("djstripe_created", models.DateTimeField(auto_now_add=True)),
+                ("djstripe_updated", models.DateTimeField(auto_now=True)),
+                ("amount", djstripe.fields.StripeQuantumCurrencyAmountField(help_text="Amount refunded.")),
+                ("currency", djstripe.fields.StripeCurrencyCodeField(help_text="Three-letter ISO currency code", max_length=3)),
+                ("balance_transaction", models.ForeignKey(help_text="Balance transaction that describes the impact on your account balance.", on_delete=django.db.models.deletion.CASCADE, to="djstripe.BalanceTransaction")),
+                ("fee", models.ForeignKey(help_text="The application fee that was refunded", on_delete=django.db.models.deletion.CASCADE, related_name="refunds", to="djstripe.ApplicationFee")),
+            ],
+            options={
+                "get_latest_by": "created",
+                "abstract": False,
+            },
+        ),
         migrations.AddField(
             model_name="charge",
             name="balance_transaction",

djstripe/models/connect.py

@@ -191,7 +191,30 @@ class ApplicationFee(StripeModel):
         "Whether the fee has been fully refunded. If the fee is only "
         "partially refunded, this attribute will still be false."
     ))
-    # TODO refunds (reverse from ApplicationFeeRefund)
+
+
+class ApplicationFeeRefund(StripeModel):
+    """
+    ApplicationFeeRefund objects allow you to refund an ApplicationFee that
+    has previously been created but not yet refunded.
+    Funds will be refunded to the Stripe account from which the fee was
+    originally collected.
+
+    Stripe documentation: https://stripe.com/docs/api#fee_refunds
+    """
+    description = None
+
+    amount = StripeQuantumCurrencyAmountField(help_text="Amount refunded.")
+    balance_transaction = models.ForeignKey(
+        "BalanceTransaction", on_delete=models.CASCADE,
+        help_text="Balance transaction that describes the impact on your account balance."
+    )
+    currency = StripeCurrencyCodeField()
+    fee = models.ForeignKey(
+        "ApplicationFee", on_delete=models.CASCADE,
+        related_name="refunds",
+        help_text="The application fee that was refunded"
+    )
 
 
 class CountrySpec(StripeModel):