BelvoApp/transactions/mixins.py

class TransactionsMixin:
    """
    TransactionMixin are essentially just a type of class mixin
    when define common functions for all Viewsets
    """

    def get_filtered_transactions(self):
        date_from = self.request.query_params.get('date_from', None)
        date_to = self.request.query_params.get('date_from', None)
        transactions = self.user.transactions
        if date_from:
            transactions = transactions.filter(date__gte=date_from)
        if date_to:
            transactions = transactions.filter(date__lte=date_to)
        return transactions