uncloud-mravi/uncloud/uncloud_pay/serializers.py

from django.contrib.auth import get_user_model
from rest_framework import serializers
from .models import *
from .helpers import get_balance_for

from functools import reduce
from uncloud_vm.serializers import VMProductSerializer
from uncloud_vm.models import VMProduct

class BillSerializer(serializers.ModelSerializer):
    class Meta:
        model = Bill
        fields = ['owner', 'amount', 'due_date', 'creation_date',
                'starting_date', 'ending_date']

class PaymentSerializer(serializers.ModelSerializer):
    class Meta:
        model = Payment
        fields = ['owner', 'amount', 'source', 'timestamp']

class PaymentMethodSerializer(serializers.ModelSerializer):
    class Meta:
        model = PaymentMethod
        fields = '__all__'

class ProductSerializer(serializers.Serializer):
    vms = VMProductSerializer(many=True, read_only=True)

class OrderSerializer(serializers.ModelSerializer):
    class Meta:
        model = Order
        fields = '__all__'

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = get_user_model()
        fields = ['username', 'email', 'balance']

    # Display current 'balance'
    balance = serializers.SerializerMethodField('get_balance')
    def __sum_balance(self, entries):
        return reduce(lambda acc, entry: acc + entry.amount, entries, 0)

    def get_balance(self, user):
        return get_balance_for(user)