JSON to JSON diff tool

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Introduction

A python module for checking equivalence and difference of two JSONs with regex support

This repository will treat two types of JSON necessary for our purpose:

1. Regular JSON where only data is stored
2. Model JSON which will treat all keys and values as regular expressions
   • Models will be used for comparing JSON objects to A model for equivalence with regex matching
   • As JSON can be in a non-deterministic order, this is harder than doing a straight string comparison

There are four modes of this module

1. Regular JSON comparison
2. JSON to Model comparison
3. Regular JSON diff
4. JSON to Model Diff

1. Regular JSON comparison

This simply tests whether two files contating json are the same

./json_diff.py path/to/file1.json path/to/file2.json

Returns True if equal or False otherwise.

.json_diff.py path/to/file1.json path/to/json_directory/

Returns the filename of the first match if there is one, or False otherwise.

2. JSON to Model comparison

This mode tests whether a given JSON file matches a model when regular expressions are evaluated.

./json_diff.py --mode j2m path/to/pure.json path/to/model.json

Returns True if the JSON and model match, False otherwise.

./json_diff.py --mode j2m path/to/pure.json path/to/model_directory

Returns the filename of the first match if there is one, or False otherwise.

3. Regular JSON diff

This mode computes a file diff between two JSON files.

The logic flow of this code is loosely based off of code found in https://github.com/monsur/jsoncompare

Assuming

old.json:

{
    "accounting" : [ {
        "firstName" : "John",
        "lastName"  : "Doe",
        "age"       : 23
    }, {
        "firstName" : "Mary",
        "lastName"  : "Smith",
        "age"       : 31
    } ],
    "sales" : [ {
        "firstName" : "Sally",
        "lastName"  : "Green",
        "age"       : 27
    }, {
        "firstName" : "Jim",
        "lastName"  : "Galley",
        "age"       : 41
    } ]
}

and new.json:

{
    "accounting" : [ {
        "firstName" : true,
        "lastName"  : "Doe",
        "age"       : 23
    }, {
        "firstName" : "Susan",
        "lastName"  : "Smith",
        "age"       : 31
    } ],
    "sales" : [ {
        "firstName" : "Sally",
        "lastName"  : "Green",
        "size"       : 27
    }, {
        "firstName" : "Jim",
        "age"       : 41
    } ]
}

Then

Should produce output like:

2015-03-24 12:59:08,576 - jsondiff - INFO - TypeDifference : accounting[0].firstName - is bool: (True), but was unicode: (John)
2015-03-24 12:59:08,576 - jsondiff - INFO - Changed: accounting[1].firstName to Susan from Mary
2015-03-24 12:59:08,576 - jsondiff - INFO - +: sales[0].size =27
2015-03-24 12:59:08,576 - jsondiff - INFO - -: sales[0].age=27
2015-03-24 12:59:08,576 - jsondiff - INFO - -: sales[1].lastName=Galley

4. JSON to Model Diff

This mode computes a file diff between a JSON file and a model with regular expressions.

*Note: at this time, we only support regular expression matching on singleton values (that is values that are NOT a list or dictionary)*

Assuming

new.json:

{
    "accounting" : [ {
        "firstName" : "John",
        "lastName"  : "Doe",
        "age"       : 23
    }, {
        "firstName" : "Mary",
        "lastName"  : "Smith",
        "age"       : 31
    } ],
    "sales" : [ {
        "firstName" : "Sally",
        "lastName"  : "Green",
        "age"       : 27
    }, {
        "firstName" : "Jim",
        "lastName"  : "Galley",
        "age"       : 41
    } ]
}

and model.json:

{
    "accounting" : [ {
        "lastName"  : "Doe",
        "age"       : 23
    }, {
        "firstName" : "Mary",
        "lastName"  : "Smith",
        "age"       : "[0-9]+"
    } ],
    "sales" : [ {
        "firstName" : "Sally",
        "lastName"  : "(.*)",
        "age"       : 24
    }, {
        "firstName" : "Jim",
        "lastName"  : "Galley",
        "age"       : 41
    } ]
}

Then

.json_diff.py -d --mode j2m new.json model.json

Should produce output

2015-03-24 12:59:08,576 - jsondiff - INFO - +: accounting[0].firstName=John
2015-03-24 12:59:08,576 - jsondiff - INFO - Changed: sales[0].age to 27 from 24

As you can see we find a match on numbers even though the type is ‘int’ (Mary Smith’s age). Also, even though we changed Sally’s age, we were still able to find a match on her entry with a regular expression representing her last name.