traverse_json.py

def traverse_json(json, predicater, value_getter, name=None):
    if predicater(name, json):
        yield value_getter(name, json)

    if isinstance(json, list):
        for obj in json:
            # Use `yield from` instead of for loop in Python 3.x
            for result in traverse_json(obj, predicater, value_getter):
                yield result

    elif isinstance(json, dict):
        for k, v in json.iteritems():
            for result in traverse_json(v, predicater, value_getter, k):
                yield result


def sophia_func(json, key):
    first, last = key.split('_')

    def predicate(name, obj):
        return name == first and isinstance(obj, dict) and last in obj

    def value_getter(name, obj):
        return obj[last]

    return list(traverse_json(json, predicate, value_getter))


def test():
    def predicate(name, obj):
        return name == 'a' and isinstance(obj, dict) and 'b' in obj

    def value_getter(name, obj):
        return obj['b']

    json = [
        {
            'a': {
                'b': 'Hello'
            },
            'b': 'Not me.',
            'c': {'a': 'b'}
        },
    ]

    result = list(traverse_json(json, predicate, value_getter))
    print result
    assert result == ['Hello']

def test_yield():
    def f():
        yield 1
        yield 2
        yield 3
        for i in xrange(10):
            yield i * 10

    for i in f():
        print i

if __name__ == '__main__':
    test()