Implement invoice model and admin API

gnuviechadmin/invoices/serializers.py

@@ -0,0 +1,33 @@
+from django.contrib.auth import get_user_model
+from rest_framework import serializers
+
+from invoices.models import Invoice
+
+User = get_user_model()
+
+
+class InvoiceSerializer(serializers.ModelSerializer):
+    customer = serializers.SlugRelatedField(
+        queryset=User.objects.all(), slug_field="username"
+    )
+
+    class Meta:
+        model = Invoice
+        fields = [
+            "url",
+            "customer",
+            "invoice",
+            "invoice_number",
+            "invoice_date",
+            "invoice_value",
+            "invoice_currency",
+            "due_date",
+            "payment_date",
+            "payment_variant",
+        ]
+        extra_kwargs = {
+            "url": {
+                "lookup_field": "invoice_number",
+                "lookup_url_kwarg": "invoice_number",
+            },
+        }