MoneyField for tastypie

moneyfield.py

from decimal import Decimal

from moneyed.classes import Money
from tastypie.fields import CharField, DecimalField
from tastypie.resources import ModelResource
from djmoney.models.fields import MoneyField as ModelMoneyField


class MoneyFieldMixin(object):
    """
    a mixin to enable moneyfields in tastypie ModelResources
    use as follows:
    
    class MyModelResource(MoneyFieldMixin, ModelResource):
         ...
         
    This will automatically convert any MoneyField into and from the respective
    serialization format:
    
    { 
      'amount' : Decimal(...),
      'currency' : "XYZ" 
    }
    
    Solves this TypeError:
      File "/tmp/env/local/lib/python2.7/site-packages/tastypie/fields.py", line 262, in convert
         return Decimal(value)
      File "/usr/lib/python2.7/decimal.py", line 658, in __new__
         raise TypeError("Cannot convert %r to Decimal" % value)
      TypeError: Cannot convert 100 EUR to Decimal

    
    """
    @classmethod
    def api_field_from_django_field(cls, f, default=CharField):
        result = ModelResource.api_field_from_django_field(f, default=default)  # @UndefinedVariable
        if isinstance(f, ModelMoneyField):
            result = ApiMoneyField
        return result
    
class ApiMoneyField(DecimalField):
    """
    MoneyField tastypie conversion
    """
    dehydrated_type = 'money'
    help_text = 'Money with amount and currency'

    def convert(self, value):
        if value is None:
            return None
        return {
            'amount' : Decimal(value.amount),
            'currency' : value.currency,
        }

    def hydrate(self, bundle):
        amount = bundle['amount']
        value = Money(amount.get('amount'), amount.get('currency'))
        return value