# Models
class Purchaser(models.Model):
    name = models.CharField(max_length=50, blank=True, null=True)
    phone = models.CharField(max_length=20, blank=True, null=True)
    email = models.EmailField(max_length=255, blank=True)
    image = models.ImageField(default='default.png', upload_to='customer_photos/%Y/%m/%d/')
    data_added = models.DateField(default=datetime.date.today)

    def __str__(self):
        return self.name

class paymentInvoice(models.Model):

    invoiceNo = models.CharField(max_length=50, unique=True, default=increment_invoice_number)
    invoiceOwner = models.ForeignKey(Purchaser, on_delete=models.CASCADE, related_name="invoice_detail")
    product = models.CharField(max_length=50, blank=True)
    date = models.DateField(default=datetime.date.today)
    quantity = models.PositiveSmallIntegerField(blank=True, default=1)
    payment_made = models.IntegerField(default=0)

    def __str__(self):
        return self.invoiceOwner.name


# Serializers
class purchaserSerializer(serializers.ModelSerializer):
    phone = serializers.StringRelatedField(read_only=True)
    email = serializers.StringRelatedField(read_only=True)
    image = serializers.StringRelatedField(read_only=True)
    data_added = serializers.StringRelatedField(read_only=True)
    class Meta:
        model = Purchaser
        fields = ('id', 'name', 'phone', 'email', 'image', 'data_added')


class paymentInvoiceSerializer(serializers.ModelSerializer):
    invoiceOwner = purchaserSerializer(many=False)
    class Meta:
        model = paymentInvoice
        fields = '__all__'


    def create(self, validated_data):
        purchaser_data = validated_data.pop("invoiceOwner")
        purchaser = Purchaser.objects.create(**purchaser_data)
        return paymentInvoice.objects.create(**validated_data)

# views
class paymentInvoiceListCreateView(ListCreateAPIView):

    serializer_class = paymentInvoiceSerializer
    queryset = paymentInvoice.objects.all().order_by('-date')

# POST data to Postman
{
    "invoiceOwner": {"name":"Becky"},
    "product": "Lix",
    "mode": "Mpesa",
    "quantity": 1,
    "status": "Pending",
    "payment_made": 3000
}

# GET data request from postman
{
    "count": 8,
    "next": null,
    "previous": null,
    "results": [
        {
            "id": 1,
            "invoiceOwner": "Martin",
            "invoiceNo": "INV-0001",
            "product": "",
            "mode": "Mpesa",
            "date": "2020-08-04",
            "quantity": 1,
            "status": "Pending",
            "payment_made": 0
        },
        {
            "id": 2,
            "invoiceOwner": "Becky",
            "invoiceNo": "INV-0002",
            "product": "",
            "mode": "Mpesa",
            "date": "2020-08-04",
            "quantity": 1,
            "status": "Pending",
            "payment_made": 0
        },
        {
            "id": 3,
            "invoiceOwner": "Maggy",
            "invoiceNo": "INV-0003",
            "product": "",
            "mode": "Mpesa",
            "date": "2020-08-04",
            "quantity": 1,
            "status": "Pending",
            "payment_made": 0
        },
        {
            "id": 4,
            "invoiceOwner": "Martin",
            "invoiceNo": "INV-0004",
            "product": "Cerrazzo",
            "mode": "Mpesa",
            "date": "2020-08-04",
            "quantity": 1,
            "status": "Paid",
            "payment_made": 2
        },
        {
            "id": 5,
            "invoiceOwner": "Maggy",
            "invoiceNo": "INV-0005",
            "product": "Sepit",
            "mode": "Mpesa",
            "date": "2020-08-04",
            "quantity": 1,
            "status": "Paid",
            "payment_made": 2000
        },
        {
            "id": 11,
            "invoiceOwner": null,
            "invoiceNo": "INV-0006",
            "product": "Lix",
            "mode": "Mpesa",
            "date": "2020-08-04",
            "quantity": 1,
            "status": "Pending",
            "payment_made": 3000
        },
        {
            "id": 12,
            "invoiceOwner": null,
            "invoiceNo": "INV-0007",
            "product": "Lix",
            "mode": "Mpesa",
            "date": "2020-08-04",
            "quantity": 1,
            "status": "Pending",
            "payment_made": 3000
        },
        {
            "id": 13,
            "invoiceOwner": null,
            "invoiceNo": "INV-0008",
            "product": "Lix",
            "mode": "Mpesa",
            "date": "2020-08-04",
            "quantity": 1,
            "status": "Pending",
            "payment_made": 0
        }
    ]
}