Access values from an object using dot notation.

get_dotted_value.py

def get_dotted_value(obj, attr=None):
    """Access values from an object using dot notation.
    
    Can be attributes, keys, or indices.

    >>> class SampleObject():
    ...     def __repr__(self):
    ...         return repr(sorted(self.__dict__.items()))
    ... 
    >>> zoo = SampleObject()
    >>> lion = SampleObject()
    >>> lion.color = "Yellow"
    >>> lion.foods = [ "zebras", "giraffes", "buffalo" ]
    >>> bear = SampleObject()
    >>> bear.color = "Brown"
    >>> bear.foods = [ "insects", "    honey    " ]
    >>> zebra = SampleObject()
    >>> zebra.color = "Striped"
    >>> zebra.foods = [ "grass", "hay" ]
    >>> zoo.animals = { 'lion': lion, 'bear': bear, 'zebra': zebra }
    >>> # simple attribute access
    ... sorted(get_dotted_value(zoo, "animals").items())
    [('bear', [('color', 'Brown'), ('foods', ['insects', '    honey    '])]), ('lion', [('color', 'Yellow'), ('foods', ['zebras', 'giraffes', 'buffalo'])]), ('zebra', [('color', 'Striped'), ('foods', ['grass', 'hay'])])]
    >>> # attribute + dictionary
    >>> get_dotted_value(zoo, "animals.lion") 
    [('color', 'Yellow'), ('foods', ['zebras', 'giraffes', 'buffalo'])]
    >>> # attribute + dictionary + attribute
    >>> get_dotted_value(zoo, "animals.lion.color") 
    'Yellow'
    >>> # attribute + dictionary + attribute + list index
    >>> get_dotted_value(zoo, "animals.lion.foods.2") 
    'buffalo'
    >>> # attribute + dictionary + attribute + list index + callable attribue
    >>> get_dotted_value(zoo, "animals.bear.foods.1.strip") 
    'honey'
    >>> 
    """
    if not attr:
        return obj
    for current_attr in attr.split('.'):
        try:
            obj = obj[current_attr]
            continue
        except AttributeError:
            pass
        except TypeError as type_err:
            if 'indices' in str(type_err):
                try:
                    obj = obj[int(current_attr)]
                    continue
                except ValueError as val_err:
                    if 'literal' not in str(val_err):
                         raise
        obj = getattr(obj, current_attr)
        if not obj:
            return
    if callable(obj):
        return obj()
    return obj

if __name__ == "__main__":
    import doctest
    doctest.testmod()