DRF - Filters in ModelSerializer - django

Question

In my models an User is related with its Profile, which has Companies. In order to serialize them I want that if the user who makes the request is_staff, then the serializer must return all the companies, not only the ones s/he has through the relationship in the model.
What's the proper way to...:
1) Check if the user is staff.
2) Return all the companies if user is staff or return the companies of the profile related with the user.
I guess the best way to deal with this would be check in BProfileSerializerRelated if the user is staff and then add something like this:
company = serializers.SerializerMethodField('get_companies')
def get_companies(self, obj):
companies = Company.objects.all()
serializer = CompanySerializer(instance=companies, many=True)
return serializer.data
My current code doesn't take into account if the user is staff so return just the companies related with that user:
models.py
class BUser(AbstractBaseUser, PermissionsMixin):
username = models.CharField(max_length=40, unique=True)
first_name = models.CharField(max_length=40)
last_name = models.CharField(max_length=40)
class BProfile(models.Model):
user = models.ForeignKey('BUser')
company = models.ForeignKey('BCompany')
groups = models.ManyToManyField(Group)
class BCompany(models.Model):
name = models.CharField(max_length=64)
dealer = models.ForeignKey(BProfile, related_name='companies', blank=True, null=True)
views.py
#api_view(['GET'])
def current_user_detail(request):
serializer = BUserSerializerRelated(request.user)
return Response(serializer.data)
serializers.py
class BUserSerializerRelated(serializers.ModelSerializer):
bprofile_set = BProfileSerializerRelated(many=True)
class Meta:
model = BUser
fields = ('id', 'bprofile_set', 'username', 'email', 'first_name', 'last_name')
class BProfileSerializerRelated(serializers.ModelSerializer):
company = CompanySerializer()
groups = GroupSerializer(many=True)
dealer_companies = CompanySerializer(many=True)
class Meta:
model = BProfile
fields = ('id', 'dealer_companies', 'company', 'groups')
class CompanySerializer(serializers.ModelSerializer):
sites = SiteSerializer(many=True)
services = ServiceSerializer(many=True)
class Meta:
model = Company
fields = ('id', 'dealer','name', 'cif', 'sites', 'services')

Answer 1

Serializer has request object in his context dict. So you can get the current user from there.
def get_companies(self, obj):
user = self.context['request'].user
if user.is_staff:
serializer = CompanySerializer(Company.objects.all(), many=True)
else:
serializer = CompanySerializer(instance=companies, many=True)
return serializer.data

Answer 2

To access request object in serializer you need to pass it context dict while initializing serializer i.e in your views.py
serializer = BUserSerializerRelated(request.user, context={'request': self.request})
then in your serializers.py, you can access request user object like
user = self.context['request'].user