how to compare two json files and get the additional values or records copied to another file in python

Question

Below are my two json file with same kind of records. As you can see it, in one file there are 3 items and in other file there are 5 items. I want those two additional items in another file.

Is there a way to compare two json files and get the additional values in the other file in python?

I found some questions related to comparing two files biut tey justgive the boolean value true or false as the result. Link to the question

===> file a.json

{
  "Count" : 3,
  "Items": [
      {
        "id"    : { "S"  : "1" },
        "name"  : { "S"  : "abc"},
        "email" : { "S"  : "abc@gmail.com"}
      },
        {
        "id"    : { "S"  : "2" },
        "name"  : { "S"  : "def"},
        "email" : { "S"  : "def@gmail.com"}
      },
      {
        "id"    : { "S"  : "3" },
        "name"  : { "S"  : "ghi"},
        "email" : { "S"  : "ghi@gmail.com"}
      }
    ],
  "ScannedCount" : 3
}

===> file b.json

{
  "Count" : 5,
  "Items": [
      {
        "id"    : { "S"  : "1" },
        "name"  : { "S"  : "abc"},
        "email" : { "S"  : "abc@gmail.com"}
      },
        {
        "id"    : { "S"  : "2" },
        "name"  : { "S"  : "def"},
        "email" : { "S"  : "def@gmail.com"}
      },
      {
        "id"    : { "S"  : "3" },
        "name"  : { "S"  : "ghi"},
        "email" : { "S"  : "ghi@gmail.com"}
      },
      {
         "id"    : { "S"  : "4" },
         "name"  : { "S"  : "jkl"},
         "email" : { "S"  : "jkl@gmail.com"}
      },
      {
         "id"    : { "S"  : "5" },
         "name"  : { "S"  : "mno"},
         "email" : { "S"  : "mno@gmail.com"}
      }
    ],
  "ScannedCount" : 5
}

Try writing some code. Let us know what you come up with. – John Zwinck Jan 13 '18 at 05:22 — John Zwinck, Jan 13 '18 at 05:22

score 1 · Answer 1 · answered Jan 13 '18 at 06:39

What you're looking for is a way to diff JSON blobs. There's several packages out there for this. Here's a few:

https://github.com/ZoomerAnalytics/jsondiff
https://pypi.python.org/pypi/json-delta/
https://github.com/seperman/deepdiff (you'll want to first parse the JSON into objects before using this one)

score 1 · Answer 2 · answered Jan 13 '18 at 06:43

1

Create objects from the file representation, compare the items, and then write output to a file.

import json

file_a = json.load(open("./a.json", "r"))
file_b = json.load(open("./b.json", "r"))

items_a = {value["id"]["S"]: value for value in file_a}
items_b = {value["id"]["S"]: value for value in file_b}

diff_keys = set(items_a) ^ set(items_b)
diff_items = {items_a[key] if items_a.has_key(key) else items_b[key] for key in diff_keys}

json.dumps(diff_items, open("file_diff.json", "w"))

answered Jan 13 '18 at 06:43

Josh Hamet

957
8
10

1

It gives me following error `File "jsondiff.py", line 6, in items_a = {value["id"]["S"]: value for value in file_a} File "jsondiff.py", line 6, in items_a = {value["id"]["S"]: value for value in file_a} TypeError: string indices must be integers` – Bhavik Joshi Jan 13 '18 at 06:58

how to compare two json files and get the additional values or records copied to another file in python

2 Answers2