Django Rest Framework 序列化程序没有得到 CharField

Question

I've built an API using Django and Django Rest Framework. In my serializer I defined an organisation which can be posted, but needs to be stored to a different model. I defined my serializer as follows:

class DeviceSerializer(serializers.HyperlinkedModelSerializer):
    geometrie = PointField(required=False)
    organisation = serializers.CharField(source='owner.organisation')
    owner = PersonSerializer(required=False)

    class Meta:
        model = Device
        fields = (
            'id',
            'geometrie',
            'longitude',
            'latitude',
            'organisation',
            'owner',
        )

    def get_longitude(self, obj):
        if obj.geometrie:
            return obj.geometrie.x

    def get_latitude(self, obj):
        if obj.geometrie:
            return obj.geometrie.y

    def create(self, validated_data):
        print("ORG:", validated_data.get('organisation', "NO ORG FOUND")) # 
        # Do some custom logic with the organisation here

But when I post some json to it, which includes an organisation (I triple checked the input), it prints the line ORG: NO ORG FOUND .

Why on earth doesn't it forward the organisation?

[EDIT]

The model code:

class Person(models.Model):
    name = models.CharField(max_length=255)
    email = models.EmailField()
    organisation = models.CharField(max_length=250, null=True, blank=True)


class Device(models.Model):
    geometrie = gis_models.PointField(name='geometrie', null=True, blank=True)
    owner = models.ForeignKey(to='Person', on_delete=models.SET_NULL, null=True, blank=True, related_name='owner')

and the test code:

def test_full_post(self):
    device_input = {
        "geometrie": {"longitude": 4.58565, "latitude": 52.0356},
        "organisation": "Administration."
    }
    url = reverse('device-list')
    self.client.force_login(self.authorized_user)
    response = self.client.post(url, data=device_input, format='json')
    self.client.logout()

Answer 1

Try changing the line:

print("ORG:", validated_data.get('organisation'], "NO ORG FOUND")) 

to this:

print("ORG:", validated_data.get('organisation', "NO ORG FOUND"))

Answer 2

Since you have added the source argument, DRF automatically push the organisation data into a nested level

So, if you want to access the organisation data, try the following,

class DeviceSerializer(serializers.HyperlinkedModelSerializer):
    organisation = serializers.CharField(source='owner.organisation')

    # other code stuffs
    def create(self, validated_data):
        

Answer 3

Pls, try 'StringRelatedField'.

class DeviceSerializer(serializers.HyperlinkedModelSerializer):

    geometrie = PointField(required=False)
    organisation = serializers.CharField(source='owner.organisation')  # yours
    # ----------------
    organisation = serializers.StringRelatedField(source='owner.organisation')  # try this.
    owner = PersonSerializer(required=False)

    # your code

Answer 4

Since you are using a serializer field with dotted notation validated_data will be:

{
'geometrie': {'longitude': 4.58565, 'latitude': 52.0356}, 
'owner': {'organisation': 'Administration.'}
}

Hence, you can access organisation as validated_data['owner']['organisation']

However, if you want to serialize a attribute/column of a another related table/foreign key you need to do use StringRelatedField [ organisation = serializers.StringRelatedField(source='owner.organisation') ] This would ensure that the 'Device instance fetched from the database contains the proper organisation attribute during a GET` request.

Deserialization won't work though and you would need additional implementation in the create method. This is because you need to create a Person instance (with the organisation ) and then connect the Device instance to that newly created instance.

A concrete example can be found here: Writing nested serializers