Reverse Nested Relationship Serialization in django rest framework - django

Question

I am working on a deals/coupon selling website. I have following models, (excluding extra details).
class Order(models.Model):
email = models.EmailField(max_length=200, null=False)
phone_number = models.CharField(max_length=10, null=False)
shipping_address = models.TextField(blank=True,null=True)
coupon_code = models.CharField(max_length=20,null=True,blank=True)
gross_total = models.FloatField(default=0.0)
class Meta:
db_table = 'order'
class OrderDetail(models.Model):
order = models.ForeignKey(Order,related_name='order_details')
package = models.ForeignKey(Package)
quantity = models.IntegerField(null=False)
unit_price = models.FloatField(default=0.0)
class Meta:
db_table = 'order_detail'
class Coupon(models.Model):
order_detail = models.ForeignKey(OrderDetail,related_name='coupons')
code = models.CharField(max_length=200, null=False, unique=True)
maximum_usage_count = models.IntegerField(null=False)
used_count = models.IntegerField(default=0)
valid_from = models.DateTimeField(null=False)
valid_to = models.DateTimeField(null=False)
class Meta:
db_table = 'coupon'
My serializers for these are,
class CouponSerializer(serializers.Serializer):
class Meta:
model = Coupon
fields = ['id', 'code', 'maximum_usage_count', 'used_count', 'valid_from', 'valid_to', 'created_at',
'updated_at', 'is_active']
class OrderDetailSerializer(serializers.Serializer):
coupons = CouponSerializer(read_only=True)
class Meta:
model = OrderDetail
fields = ['id', 'package', 'quantity', 'unit_price', 'created_at', 'updated_at', 'is_active']
class OrderSerializer(serializers.ModelSerializer):
order_details = OrderDetailSerializer(read_only=True,many=True)
class Meta:
model = Order
fields = ['id','email', 'phone_number', 'shipping_address', 'coupon_code', 'gross_total','order_details']
In my listapiview, for fetching all orders, I have specified the order serializer. The api is working fine but is not able to serialize the reverse relation ship models. I am getting following response.
{
"id": 31,
"email": "ff#b.com",
"first_name": "ff",
"last_name": "ff",
"phone_number": "ff",
"shipping_address": "",
"coupon_code": "",
"gross_total": 1.0,
"payment_method": "ONLINE",
"order_status": "PLACED",
"created_at": "2016-10-01T17:26:00.432000",
"updated_at": "2016-10-01T17:48:50.797000",
"is_active": true,
"order_details": [
{
"coupons": {}
},
{
"coupons": {}
},
{
"coupons": {}
}
]
}

Answer 1

I think you should replace the inherited class with serializers.ModelSerializer in CouponSerializer and OrderDetailSerializer instead of just serializer.Serializer - just like you did in OrderSerializer.
After that you'll get some errors because your models (Coupon and OrderDetail) don't declare any of created_at, updated_at nor is_active fields. So you should add those fields to your models or remove them from the list in Meta in both serializer classes. But after that it works as expected.