DRF Serializers. Different fields on serialize and deserialize methods - serialization

Question

What is the best approach to have the same field name in Serializer but different behaviour on serializing and deserializing data? (I want to put only group_id on input and get full related info on the output)
So I want my schema looks like this when I input my data
{
"group": 1,
"other_fields": []
...
}
But got this (This is the way i want data looks like on the output only)
{
"group": {
"name": "string",
"description": "string",
"image": "string",
"is_public": true
},
"other_fields": []
...
}
My serializer right now
class TaskSerializer(serializers.ModelSerializer):
group = GroupSerializer()
class Meta:
model = Task
fields = "__all__"
Edit: Added group serializer and my Group model. Nothing special
class GroupSerializer(serializers.ModelSerializer):
class Meta:
model = Group
fields = "id", "owner", "name", "description", "image", "is_public"
read_only_fields = "owner",
class Group(models.Model):
name = models.CharField(max_length=32)
owner = models.ForeignKey("user.User", on_delete=models.CASCADE)
description = models.CharField(max_length=32)
image = models.ImageField(upload_to=func)
is_public = models.BooleanField(default=True)

Answer 1

In your TaskSerializer class you are serializing group with GroupSerializer(), which serializes the relation as an object with the fields you specified in it's implementation.
You instead want to serialize a single field, for that you could use SlugRelatedField(slug_field='id') which serializes the relation as a single field from group.
Because your Group model doesn't have a primary key field, Django generates an automatic AutoField(primary_key=True) id field, thus you can use PrimaryKeyRlatedField().
Try:
class TaskSerializer(serializers.ModelSerializer):
group = serializers.PrimaryKeyRelatedField()
class Meta:
model = Task
fields = "__all__"
For more examples, I suggest reading this tip from testdriven.io.