J2J

J2J is a rule engine library that helps in converting one form of JSON into another by applying some rules on top of the input JSON.

J2J is a thin layer that sits on top of the application layer converting the input JSON into the expected JSON. It'll be helpful when the request data POSTed on to the server is different from what the application expects.

For eg:- Let us consider, you have designed a base platform which has exposed some of its APIs. Now, due to some (business partnership) reasons, the client cannot POST the data as per the expected format. Use J2J to convert the input JSON into expected JSON WITHOUT CHANGING YOUR APIs for a specific business partner.

Installation

pip install j2j

Quick start

import j2j

input = {
    "k1": "v1",
    "k2": ["v40", "v41", "v42", "v43", "v44", "v45"],
    "k3": {
        'a': 1
    },
    "k4": {
        'a': {
            'b': 3
        }
    }
}

rules = {
    "rules": [
        {
            "base_elem": "/",
            "changes": {
                "newk1": "k1",
                "newk2": "k2@0",
                "k3.newa": "k3.a",
                "k4.newa.newb": "k4.a.b"
            },
            "keep_others": True,
            "make_base": False,
            "new_key_elem": "/"
        }

    ]
}

>>> print(j2j.convert(input, rules))

{'newk1': 'v1', 'k3': {'newa': 1}, 'k4': {'newa': {'newb': 3}}, 'newk2': 'v40'}

Configuration

Splitters

• To split by dict, use .

• To split by array, use @

• Root Element is /

• End of array is $

• All items is *

Rule Configuration

• base_element - For future use. Element(or key) where you want to start the navigation.

For eg, for the above input, if base_element is set as k4, then the changes will be done only inside the element k4. Rest will remain unchanged (if keep_others is True, else output will only return the changes done inside k4).

• keep_others - For future use. Setting to keep other keys in the output along with the changes done.

• new_key_elem - For future use. Useful when base_elem is some key other than root element.

• make_base - For future use.

• changes - Include changes that need to be done on the input JSON.

For the above applied rules, following changes will be made.

1) A new key `newk1` will be created having the value of `k1`.

2) A new key `newk2` will be created having the value of the `0th` index of `k2`

3) `k3.newa` means a new key `newa` will be created inside `k3` having value `k3.a`.

Recommendations

• Create a separate rules.json file, read it and then pass the loaded json to the function.

Use the following settings for the time-being. Working on their implementations.

• base_elem as root element \.

• keep_others as True.

• make_base as True.

• base_elem as root element \.

TODO

• Apply multiple rules on the same input JSON. (Work in Progress)

• keep_others when base element is root (\).

• Create new keys by concatenating 2 or more keys.

Contribution Guidelines

• Writing tests - Always welcome to improve on this.

• Other guidelines - Feel free to suggest any more feature or raise a PR to contribute in fixing bugs.