import logging
import json

log = logging.getLogger(__name__)


def flatten(key, items):
    if items is None:
        return []
    return [item.get(key) for item in items if item.get(key)]


class DatetimeEncoder(json.JSONEncoder):
    """
    Alternate handler that can serialize dates
    """
    def default(self, obj):
        if hasattr(obj, 'isoformat'):
            return obj.isoformat()
        # Let the base class default method raise the TypeError
        return json.JSONEncoder.default(self, obj)