Django Rest框架 - Django嵌套序列化器一对多关系

Question

I have three models : User(django auth model), Consumer, Tasks .

User model and Consumer has one to one relationship and Consumer and Task has one to many relationship.

My model.py goes like this:

class Consumer(models.Model):
    user=models.OneToOneField(User,on_delete=models.CASCADE)    
    average_rating=models.FloatField(default=5.0)

class Tasks(models.Model):

    consumer=models.ForeignKey(Consumer,on_delete=models.CASCADE,related_name='consumer_obj')
    title=models.CharField(max_length=50)
    description=models.CharField(max_length=200)
    added_on=models.DateTimeField(auto_now=True)

My serializers.py goes like this:

class TaskSerializer(serializers.ModelSerializer):

    category=serializers.CharField(max_length=10)
    class Meta:
        model=Tasks
        fields=['title','description']

class UserSerializer(serializers.ModelSerializer):
    password=serializers.CharField(max_length=10,write_only=True)
    class Meta:
        model=User 
        fields=['username','password','email']


class ConsumerSerializer(serializers.ModelSerializer):
    user=UserSerializer()
    tasks=TaskSerializer(many=True,source='consumer_obj')
    class Meta:
        model=Consumer
        fields=['user','average_rating','tasks']

Now what I want to do is, Whenever I save a post a task, it should get save the task and associate itself to the current Consumer.

What can be done.

Now, whenever I call serializer.save() in my views I can pass a user instance as an argument something like this

 serializer.save(user=request.user)

And in my serializer create() function I can query the user and than query the consumer with the help of user to associate the task with that user.

I want to know if there is any better way to do this ? I'm new to DRF and having hard time learning it.

Answer 1

you can Use the same approach that DRF uses for User, write a Custom object like CurrentUserDefault that returns the consumer correspondent to the currently authenticated user:

from rest_framework.compat import unicode_to_repr

class CurrentConsumerDefault(object):
    def set_context(self, serializer_field):
        user = serializer_field.context['request'].user
        self.consumer = user.consumer

    def __call__(self):
        return self.consumer

    def __repr__(self):
        return unicode_to_repr('%s()' % self.__class__.__name__)

note: you should use the generic view or provide the request for the serializer yourself.

then in your TaskSerializer , add this field:

class TaskSerializer(serializers.ModelSerializer):

    consumer=serializers.HiddenField(default=CurrentConsumerDefault())

    class Meta:
        model=Tasks
        fields=['title','description', 'consumer']

read my answer to a similar question for more information.