Default functions and methods to use with json.dumps for returning valid, full JSON representations of your domain models.

gistfile1.py

from mongoalchemy.document import Value
from pymongo.objectid import ObjectId
from market import DB


def remove_OIDs(obj, recursive=False):
    """
    Removes the ObjectID types from an object
    before returning
    """
    if isinstance(obj, list):
        return [remove_OIDs(ob) for ob in obj]
    elif isinstance(obj, AppModel):
        response = obj.clean4_dump()
        return response


def json_clean(field_value):
    """
    Removes the ObjectID types from an object
    before returning
    """
    if isinstance(field_value,
            ObjectId):
        return str(field_value)
    elif isinstance( field_value,
            Value):
        return field_value.value
    elif isinstance( field_value, list) or isinstance( field_value, tuple):
        return [ json_clean(value) for value in field_value ]
    elif isinstance( field_value,
            dict):
        return dict( [ (str(key), json_clean(value)) for key, value in field_value.items() ])
    return field_value


class AppModel(DB.Document):
    _self_link = DB.StringField(required=False)
    _parent_link = DB.StringField(required=False)
    filter_fields = tuple()

    @classmethod
    def has_key(cls, key):
        return hasattr(cls, key)

    @classmethod
    def get(cls, key, default=None):
        return getattr(cls, key) or default

    def filter_out_fields(self, remove_keys):
        return dict([(key_, getattr(self, key_))
            for key_ in self.get_fields().iterkeys()
            if key_ not in remove_keys and hasattr(self, key_)
            ])

    def clean4_dump(self):
        """
        Removes the ObjectID types from an object
        before returning
        """
        response = dict(self._values)
        for field in self._fields:
            try:
                field_value = self.__getattribute__(field)
                if field == 'mongo_id': field = 'id'
                response[field] = field_value
                response[field] = json_clean(field_value)
            except AttributeError:
                continue
        response = dict([(key, value) for key, value in response.items() if key not in [field._name for field in self.filter_fields]])
        return response