Extracting values from an arbitrary JSON data structure

A friend of mine came to me for help with a Python programming problem: he needed a way to extract some values from a JSON data structure by specifying the full path of each value; for example, given the following data structure:

{
  "name": "cavallo",
  "attributes": {
    "good": "goloso",
    "bad": "dispettoso"
  }
}

he wanted to be able to extract name and attributes.good. One of my friend’s requirements was that the code should read the list of paths from an external file, so that he could decouple code from configuration.

I came up with the following Python function, which is an iterator that yields tuples of (path, value) while walking the input JSON data structure:

The JSON data structure used as test case can be found on the gist page.

Demo:

$ python walk_json.py sample.json
(u'stats.timestamp', u'2016-07-02T13:35:07.076830981Z')
(u'stats.memory.usage', 49815552)
(u'stats.cpu.usage.total', 1526446336302)
(u'stats.cpu.usage.user', 1161250000000)
(u'name', u'/init.scope/system.slice/docker-7f9ed89c7297f99669b6e79d9d8d404d19f160ca40b40f42896506fa7942786b.scope')
(u'spec.has_network', False)