BelvoApp/transactions/serializers.py

from rest_framework import serializers
from .models import Transaction
from django.utils.translation import ugettext_lazy as _
from django.contrib.auth import get_user_model

User = get_user_model()


class CreateTransactionSerializer(serializers.ModelSerializer):
    user_id = serializers.PrimaryKeyRelatedField(
        queryset=User.objects.all(), source='user', write_only=True, help_text='User Id')

    def __init__(self, *args, **kwargs):
        many = kwargs.pop('many', True)
        super(CreateTransactionSerializer, self).__init__(many=many, *args, **kwargs)

    def validate(self, data):
        """
        Check the type is outflow or inflow
        Check the inflow is positive and outflow is negative
        """
        if data['type'] not in ('outflow','inflow'):
            raise serializers.ValidationError({"type": _("Must be `outflow` or `inflow` ")})
        if data['amount'] > 0 and data['type'] == 'outflow':
            raise serializers.ValidationError({"amount":_("Outflow type only allow negatives amount")})
        if data['amount'] < 0 and data['type'] == 'inflow':
            raise serializers.ValidationError({"amount":_("Inflow type only allow positives amount")})
        return data

    class Meta:
        model = Transaction
        fields = ('user_id', 'reference', 'account', 'type', 'amount', 'category','date')


class BalanceByAccountSerializer(serializers.ModelSerializer):

    balance = serializers.FloatField(label='balance', read_only=True)
    total_inflow = serializers.FloatField(label='balance', read_only=True)
    total_outflow = serializers.FloatField(label='balance', read_only=True)

    class Meta:
        model = Transaction
        fields = ['account', 'balance','total_inflow','total_outflow']