django rest framework - how do you flatten nested data?

Question

I have a 'through' model governing a many to many relationship and i want to be able to return the 'through' model and the target model as flat data, as opposed to having the target model nested. So using the standard example for a many to many with a through, say these are the models, ``` class Person(models.Model): first_name = models.CharField(max_length=128) last_name = models.CharField(max_length=128) favourite_food = models.CharField(max_length=128) class Group(models.Model): name = models.CharField(max_length=128) members = models.ManyToManyField(Person, through='Membership') class Membership(models.Model): person = models.ForeignKey(Person) group = models.ForeignKey(Group) date_joined = models.DateField() invite_reason = models.CharField(max_length=64) ``` So the serializers i have at the moment to return Membership items are, ``` class MembershipSerializer(serializers.HyperlinkedModelSerializer): person = PersonSerializer() class Meta: model = Membership fields = ('id', 'url'…

Accepted Answer

I'm not convinced this is the simplest way, but the solution i came up with was to override the to_native method of the MembershipSerializer and then manually create and invoke the to_native method of the PersonSerializer and merge the two resulting dictionary's together

```
class MembershipSerializer(serializers.HyperlinkedModelSerializer):

def to_native(self, obj):

ret = super(MembershipSerializer, self).to_native(obj)
        p_serializer = PersonSerializer(obj.person, context=self.context)
        p_ret = p_serializer.to_native(obj.person)

for key in p_ret:
            ret[key] = p_ret[key]

return ret

class Meta:
        model = Membership
        fields = ('id', 'url', 'group', 'date_joined', 'invite_reason', 'person')
```

The dictionary's are both a subclass of SortedDict. I'm not sure whether there's an explicit method to merge the two that preserves the order, so i've just used a loop instead.

django rest framework - how do you flatten nested data?

Solution

Problem