def sort_helper(object_list, sort_list, db_field_map=None):
    """
    Helper method for sorting object_lists.

    @param  object_list     An array of objects to sort.
    @param  sort_list       An array of names to sort by.
    @param  db_field_map    An optional dictionary that maps a sort name to an object's property or method.
    @return The sorted list
    """

    def clean(x):
        """
        Function that cleans the value to sort by.
        
        @param  x    The attribute on the object.
        @return The cleaned up value for sorting.
        """

        # attribute is a method so get the returned value
        v = x() if callable(x) else x

        # attribute is a string so convert it to lower case
        if type(v) == str or type(v) == unicode:
            v = v.lower()

        # attribute is a datetime so convert it to an epoch value
        elif type(v) == datetime.datetime:
            v = time.mktime(v.timetuple())

        # return the value
        return v
                

    # reverse the sort order so we get the correct sub-sorting
    sort_order = reversed(sort_list)
            
    # Generate the actual list of attributes we'll be sorting by
    for sort_item in sort_order:

        # -name so sort this attribute descending
        if sort_item[0] == '-':
            base_sort_item = sort_item[1:]
            reverse = True

        # Otherwise sort in ascending order
        else:
            base_sort_item = sort_item
            reverse = False
        
        # Check if the name is in the db field map   
        if db_field_map:
            if not base_sort_item in db_field_map: 
                continue
            db_field = db_field_map[base_sort_item]
        else:
            db_field = base_sort_item

        # Do the actual sort now
        try:
            object_list = sorted(object_list, key=lambda x: clean(getattr(x, db_field)), reverse=reverse)                
        except Exception, e:
            logging.exception('sort_helper - %s' % unicode(e))
            
    return object_list