jsonhash

Json elective hash

Calculates hash sha256 of JSON objects with ignoring some fields option and array order unimportance. It can work with common golang objects, but correctness is not guaranteed

Usage

The most simple variant

import "github.com/SergJa/jsonhash"

func main() {
	jsonContent, err := ioutil.ReadFile("file.json")
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		return
	}
	hash, err := jsonhash.CalculateJsonHash(jsonContent, []string{})
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		return
	}
	fmt.Println(hex.EncodeToString(hash[:]))
}

You may use already unmarshalled object

hash, err := jsonhash.CalculateHash(unmarshalledObject, []string{})

If you need to ignore some fields, you can fill the second parameter. There you can describe fields using dot (".") as separator and leader of each string. Iportant! Every string must begin with dot. Example: []string{".uuid"} - field with name uuid will be ignored while hash calculaion.

Example 2:

[]string{".subobj.subfield"}

{
 "field1": "data1",
 "subobj": {
  "subfield": "will be ignored",
  "else_field": "will take part in hash calculation"
 }
}

Arrays do not consider level. Example 3:

[]string{".subobj.subfield"}

{
 "subarr": [
  {
   "subfield": "will be ignored",
   "else_field": "will take part in hash calculation"
  },
  {
   "subfield": "will be ignored",
   "else_field2": "will take part in hash calculation"
  }
 ]
}

Object hashCalculator

If you need to count plenty of hashes with same ignoring fields list, you can use hashCalculator. Creating:

calc := jsonhash.NewHashCalculator([]string{".field.subfield"})

This calc has just the same methods as described below, excluding second parameter whith ignoring fields list. This list will be taken from calc. Example:

calc := jsonhash.NewHashCalculator([]string{".ignoreme", ".ignoreme_root.ignore"})

hash, err := calc.CalculateJsonHash([]byte(`{"json":content", "ignoreme":"anything"}`))

hash2, err := calc.CalculateJsonHash([]byte(`{"ignoreme_root":{"ignore": "anything"}`))