doccano/backend/members/serializers.py

from rest_framework import serializers

from .models import Member


class MemberSerializer(serializers.ModelSerializer):
    username = serializers.SerializerMethodField()
    rolename = serializers.SerializerMethodField()

    @classmethod
    def get_username(cls, instance):
        user = instance.user
        return user.username if user else None

    @classmethod
    def get_rolename(cls, instance):
        role = instance.role
        return role.name if role else None

    class Meta:
        model = Member
        fields = ('id', 'user', 'role', 'username', 'rolename')