Find all occurrences of a key in nested python dic

Question

I have a dictionary like this:

{ "id" : "abcde",
  "key1" : "blah",
  "key2" : "blah blah",
  "nestedlist" : [ 
    { "id" : "qwerty",
      "nestednestedlist" : [ 
        { "id" : "xyz",
          "keyA" : "blah blah blah" },
        { "id" : "fghi",
          "keyZ" : "blah blah blah" }],
      "anothernestednestedlist" : [ 
        { "id" : "asdf",
          "keyQ" : "blah blah" },
        { "id" : "yuiop",
          "keyW" : "blah" }] } ] } 

Basically a dictionary with nested lists, dictionaries and strings, of arbitrary depth.

What is the best way of traversing this to extract the values of every "id" key? I want to achieve the equivalent of an XPath query like "//id". The value of "id" is always a string.

So from my example, the output I need is basically:

["abcde", "qwerty", "xyz", "fghi", "asdf", "yuiop"]

Order is not important.

Answer 1

Here's how I did it.

This function recursively searches a dictionary containing nested dictionaries and lists. It builds a list called fields_found, which contains the value for every time the field is found. The 'field' is the key I'm looking for in the dictionary and its nested lists and dictionaries.

def get_recursively(search_dict, field):
    """Takes a dict with nested lists and dicts,
    and searches all dicts for a key of the field
    provided.
    """
    fields_found = []

    for key, value in search_dict.iteritems():

        if key == field:
            fields_found.append(value)

        elif isinstance(value, dict):
            results = get_recursively(value, field)
            for result in results:
                fields_found.append(result)

        elif isinstance(value, list):
            for item in value:
                if isinstance(item, dict):
                    more_results = get_recursively(item, field)
                    for another_result in more_results:
                        fields_found.append(another_result)

    return fields_found

Answer 2

d = { "id" : "abcde",
    "key1" : "blah",
    "key2" : "blah blah",
    "nestedlist" : [ 
    { "id" : "qwerty",
        "nestednestedlist" : [ 
        { "id" : "xyz", "keyA" : "blah blah blah" },
        { "id" : "fghi", "keyZ" : "blah blah blah" }],
        "anothernestednestedlist" : [ 
        { "id" : "asdf", "keyQ" : "blah blah" },
        { "id" : "yuiop", "keyW" : "blah" }] } ] } 


def fun(d):
    if 'id' in d:
        yield d['id']
    for k in d:
        if isinstance(d[k], list):
            for i in d[k]:
                for j in fun(i):
                    yield j

---

>>> list(fun(d))
['abcde', 'qwerty', 'xyz', 'fghi', 'asdf', 'yuiop']