Django Nested Serializer

Question

I am pretty new to DRF/Django and want to create an endpoint that returns nested json from multiple models in the format:

    { 
        "site": {  
            "uuid": "99cba2b8-ddb0-11eb-bd58-237a8c3c3fe6",
            "domain_name": "hello.org"
            },

       "status": "live",

       "configuration": {   
            "secrets": [  
            {
             "name": "SEGMENT_KEY", # Configuration.name
             "value": [...] # Configuration.value
            },
           {
             "name": "CONFIG_KEY",
             "value": [...]
            },

        "admin_settings": {
            'tier'='trail',
            'subscription_ends'='some date',
            'features'=[]
        }

Here are the models:

class Site(models.Model):
    uuid = models.UUIDField(
        default=uuid.uuid4,
        editable=False,
        unique=True)
    domain_name = models.CharField(max_length=255, unique=True)
    created = models.DateTimeField(editable=False, auto_now_add=True)
    modified = models.DateTimeField(editable=False, auto_now=True)

class AdminConfiguration(models.Model):
    TRIAL = 'trial'
    PRO = 'pro'
    TIERS = [
        (TRIAL, 'Trial'), 
        (PRO, 'Professional'),
    ]
    site = models.OneToOneField(
        Site,
        null=False,
        blank=False,
        on_delete=models.CASCADE)
    tier = models.CharField(
        max_length=255,
        choices=TIERS,
        default=TRIAL)
    subscription_ends = models.DateTimeField(
        default=set_default_expiration)
    features = models.JSONField(default=list)


class Configuration(models.Model):
    CSS = 'css'
    SECRET = 'secret'
    TYPES = [
        (CSS, 'css'),
        (SECRET, 'secret')
    ]
    LIVE = 'live'
    DRAFT = 'draft'
    STATUSES = [
        (LIVE, 'Live'),
        (DRAFT, 'Draft'),
    ]
    site = models.ForeignKey(Site, on_delete=models.CASCADE)
    name = models.CharField(max_length=255, blank=False)
    type = models.CharField(
        max_length=255,
        choices=TYPES)
    value = models.JSONField(
        null=True)
    status = models.CharField(
        max_length=20,
        choices=STATUSES)

Logic behind serializer/viewset to achieve mentioned json:

retrieves lookup_field: uuid
filters query param: Configuration.status (either live or draft
filters AdminConfiguration on site id (something like AdminConfiguration.objects.get(Site.objects.get(uuid))
filters Configuration on type = secret

Here are my serializers:

class SiteSerializer(serializers.ModelSerializer):
    class Meta:
        model = Site
        fields = [
            'uuid',
            'domain_name'
        ]

class AdminSerializer(serializers.ModelSerializer):
    class Meta:
        model = AdminConfiguration
        fields = [
            'tier',
            'subscription_ends',
            'features'
        ]

class ConfigurationSubSerializer(serializers.ModelSerializer):    
    class Meta:
        model = Configuration
        fields = [
            'name',
            'value',
        ]

class SecretsConfigSerializer(serializers.ModelSerializer):
    site = SiteSerializer()
    admin_settings = AdminSerializer()
    status = serializers.CharField()
    configuration = ConfigurationSubSerializer(many=True, source='get_secret_config')

    class Meta:
        model = Configuration
        fields = [
            'site',
            'admin_settings',
            'status'
            'configuration'
        ]

    def get_secret_config(self, uuid):
        site = Site.objects.get(uuid=self.context['uuid'])
        if self.context['status'] == 'live' or self.context['status'] == 'draft':
            return Configuration.objects.filter(
                        site=site,
                      status=self.context['status'],
                        type='secret'
                    )

Viewset:

class SecretsViewSet(viewsets.ReadOnlyModelViewSet):
    model = Site
    lookup_field = 'uuid'
    serializer_class = SecertsConfigSerializer
    filter_backends = (DjangoFilterBackend,)
    filterset_fields = ['status'] #query params

    def get_serializer_context(self):
        return {
            'status': self.request.GET['status'],
            'uuid': self.request.GET['uuid']
        }

    def get_serializer(self, *args, **kwargs):
        kwargs['context'] = self.get_serializer_context()
        return CombinedConfigSerializer(*args, **kwargs)

What am I missing to achieve the desired output?

output from django shell:

from site_config.models import Site, AdminConfiguration, Configuration
from site_config.serializers import SecretsConfigSerializer

site = Site.objects.get(id=2)
s = SecretsConfigSerializer(site)
s.data

### OUTPUT ###
AttributeError: Got AttributeError when attempting to get a value for field `site` on serializer `SecretsConfigSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `Site` instance.
Original exception text was: 'Site' object has no attribute 'site'.

Please update the question with the output format that you are getting now. — drec4s
– drec4s, Commented Aug 9, 2021 at 22:25
@afonso I added the output from the django shell above - thanks! — Esther Suh
– Esther Suh, Commented Aug 9, 2021 at 22:33
SecretsConfigSerializer is configured as a model serializer for Configuration, so why are you using it for a Site object? — Brian Destura
– Brian Destura, Commented Aug 10, 2021 at 1:39
@bdbd good question... to be frank, I'm not sure what to pass into SecretsConfigSerializer - I tried passing in a Configuration object but getting the same error — Esther Suh
– Esther Suh, Commented Aug 10, 2021 at 2:15
You mean when using Configuration, you get Original exception text was: 'Site' object has no attribute 'site'.? — Brian Destura
– Brian Destura, Commented Aug 10, 2021 at 3:03

Oscar Gonzalez · Accepted Answer · 2021-08-09 23:27:18Z

2

Why you don't try something more general and build your response separating the serializers like this (maybe you can use the same serializers in somewhere else):

def get(self, request, *args, **kwargs):
   resp = {
           'site': None,
           'status': None,
           'configuration': None,
           'admin_settings': None,
        }
   sites = models.Site.objects.all()
   resp['site'] = serializers.SitesSerializer(sites, many=True).data
   admin_settings = models.AdminConfiguration.objects.all()
   resp['admin_settings'] = serializers.AdminConfigurationSerializer(admin_settings, many=True).data
   # and so
   return Response(resp, status=status.HTTP_200_OK)

answered Aug 9, 2021 at 23:27

Oscar Gonzalez

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1 Comment

Esther Suh Over a year ago

thank you for suggesting this! way simpler and more readable

MD. SHIFULLAH · Accepted Answer · 2023-07-03 10:26:36Z

You can try it like this. This will also help to find out errors:

def get(self, request, *args, **kwargs):
    resp = {
        "site": None,
        "status": None,
        "configuration": None,
        "admin_settings": None
    }
    sites = models.Site.objects.all()
    resp['site'] = serializers.SitesSerializer(sites, many=True).data
    if resp['site'].is_valid():
        admin_settings = models.AdminConfiguration.objects.all()
        resp['admin_settings'] = serializers.AdminConfigurationSerializer(admin_settings, many=True).data
        if resp['admin_settings'].is_valid():
            return Response(resp, status=status.HTTP_200_OK)
        return Response(resp['admin_settings'].errors, status=status.HTTP_404_NOT_FOUND)
    return Response(resp['site'].errors, status=status.HTTP_404_NOT_FOUND)

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