How to combine two arrays (`keys` and `values`) into an object using JMESPath?

Question

I have a JSON object with two arrays — one keys array and one values array, both of the same length. Using jmespath, I want to construct a new object using the values of the keys array as the keys and the values of the values array as the values, like array_combine in PHP.

For example, here's the input:

{
    "keys": [
        "a",
        "b",
        "c"
    ],
    "values": [
        1,
        2,
        3
    ]
}

And here is the output I'm expecting:

{
    "a": 1,
    "b": 2,
    "c": 3
}

Is there any built-in function to achieve this?

Dualistic

Answer 1

Unfortunately, it looks like this is not possible yet.

Github issue: jmespath.py#152 — (located in the repo of the Python implementation)

You would need the zip and from_items functions, proposed (!) for the specs in this github pull request.

Villasenor

Answer 2

jmespath is popular library to parse/query JSON files. More examples at http://jmespath.org/tutorial.html

In below code

• js is the provided json content
• jp.search('keys',json.loads(js)) produces the list : [u'a', u'b', u'c']
• jp.search('values',json.loads(js)) produces the list : [1, 2, 3]

• zip combines the two lists and dict() converts the tuples to a dictionary

  import json
  import jmespath
  
  js = '''{
          "keys": [
                  "a",
                  "b",
                  "c"
                  ],
          "values": [
                  1,
                  2,
                  3
                    ]
          }'''
  
  print (dict(zip(jp.search('keys',json.loads(js)),jp.search('values',json.loads(js)))))
  

  output: {u'a': 1, u'c': 3, u'b': 2}

Apograph

Please consider adding some wording to explain what you have done with the code. – Sergio

Sure, added more details. – Apograph

@Sai, I appreciate the effort, but I was looking for a solution that used jmespath only and your solution uses Python to zip the two arrays. The reason for wanting a jmespath-only approach is I want to build an API where users provide a jmespath script to reshape a JSON response to their liking without compromising the server by executing arbitrary Python code. – Dualistic