Diff program for JSON dictionaries

README.md

JSON Differ

Usage

$ jdiff.py from-file to-file

jdiff.py

#!/usr/bin/env python

import sys
import json

def string_from_keypath(keypath):
    return 'dict["' + ('"]["'.join(keypath)) + '"]'

class ValueChange(object):
    def __init__(self, keypath, lhs, rhs):
        self.keypath = keypath
        self.lhs = lhs
        self.rhs = rhs

    def dump(self):
        print "@@ ", string_from_keypath(self.keypath), " @@"
        print "- ", self.lhs
        print "+ ", self.rhs

class KeyAddition(object):
    def __init__(self, keypath, value):
        self.keypath = keypath
        self.value = value

    def dump(self):
        print "@@ ", string_from_keypath(self.keypath), " @@"
        print "+ ", self.value

class KeyDeletion(object):
    def __init__(self, keypath, value):
        self.keypath = keypath
        self.value = value

    def dump(self):
        print "@@ ", string_from_keypath(self.keypath), " @@"
        print "- ", self.value


def recursive_diff(keypath, lhs, rhs):
    if type(lhs) != type(rhs):
        return [ValueChange(keypath, lhs, rhs)]
    if type(rhs) != dict:
        if lhs != rhs:
            return [ValueChange(keypath, lhs, rhs)]
        else:
            return []

    changes = []
    for key in lhs.keys():
        if key not in rhs.keys():
            changes += [KeyDeletion(keypath + [key], lhs[key])]

    for key in rhs.keys():
        if key not in lhs.keys():
            changes += [KeyAddition(keypath + [key], rhs[key])]

    for key in lhs.keys():
        if key in rhs.keys():
            changes += recursive_diff(keypath + [key], lhs[key], rhs[key])

    return changes

def main():
    lhs_filename = sys.argv[1]
    with open(lhs_filename, "r") as lhs_file:
        lhs_text = lhs_file.read()
    lhs = json.loads(lhs_text)

    rhs_filename = sys.argv[2]
    with open(rhs_filename, "r") as rhs_file:
        rhs_text = rhs_file.read()
    rhs = json.loads(rhs_text)

    changes = recursive_diff([], lhs, rhs)

    if len(changes) == 0:
        sys.exit(0)

    print "--- ", sys.argv[1]
    print "+++ ", sys.argv[2]

    for change in changes:
       change.dump()

    sys.exit(-1)

if __name__ == "__main__":
    main()