Compare json equality in Scala - json

Question

How can I compare if two json structures are the same in scala?
For example, if I have:
{
resultCount: 1,
results: [
{
artistId: 331764459,
collectionId: 780609005
}
]
}
and
{
results: [
{
collectionId: 780609005,
artistId: 331764459
}
],
resultCount: 1
}
They should be considered equal

Answer 1

You should be able to simply do json1 == json2, if the json libraries are written correctly. Is that not working for you?
This is with spray-json, although I would expect the same from every json library:
import spray.json._
import DefaultJsonProtocol._
Welcome to Scala version 2.10.4 (OpenJDK 64-Bit Server VM, Java 1.7.0_51).
Type in expressions to have them evaluated.
Type :help for more information.
scala> val json1 = """{ "a": 1, "b": [ { "c":2, "d":3 } ] }""".parseJson
json1: spray.json.JsValue = {"a":1,"b":[{"c":2,"d":3}]}
scala> val json2 = """{ "b": [ { "d":3, "c":2 } ], "a": 1 }""".parseJson
json2: spray.json.JsValue = {"b":[{"d":3,"c":2}],"a":1}
scala> json1 == json2
res1: Boolean = true
Spray-json uses an immutable scala Map to represent a JSON object in the abstract syntax tree resulting from a parse, so it is just Map's equality semantics that make this work.

Answer 2

You can also use scalatest-json
Example:
it("should fail on slightly different json explaining why") {
val input = """{"someField": "valid json"}""".stripMargin
val expected = """{"someField": "different json"}""".stripMargin
input should matchJson(expected)
}
When the 2 jsons doesn't match, a nice diff will be display which is quite useful when working with big jsons.

Answer 3

Can confirm that it also works just fine with the Jackson library using == operator:
val simpleJson =
"""
|{"field1":"value1","field2":"value2"}
""".stripMargin
val simpleJsonNode = objectMapper.readTree(simpleJson)
val simpleJsonNodeFromString = objectMapper.readTree(simpleJsonNode.toString)
assert(simpleJsonNode == simpleJsonNodeFromString)

Answer 4

spray-json is definitely great, but I use Gson since I already had dependency on Gson library on my project. I am using these in my unit tests, works well for simple json.
import com.google.gson.{JsonParser}
import org.apache.flume.event.JSONEvent
import org.scalatest.FunSuite
class LogEnricherSpec extends FunSuite {
test("compares json to json") {
val parser = new JsonParser()
assert(parser.parse("""
{
"eventType" : "TransferItems",
"timeMillis" : "1234567890",
"messageXml":{
"TransferId" : 123456
}
} """.stripMargin)
==
parser.parse("""
{
"timeMillis" : "1234567890",
"eventType" : "TransferItems",
"messageXml":{
"TransferId" : 123456
}
}
""".stripMargin))
}

Answer 5

Calling the method compare_2Json(str1,str2) will return a boolean value.
Please make sure that the two string parameters are json.
Welcome to use and test.
def compare_2Json(js1:String,js2:String): Boolean = {
var js_str1 = js1
var js_str2 = js2
js_str1=js_str1.replaceAll(" ","")
js_str2=js_str2.replaceAll(" ","")
var issame = false
val arrbuff1 = ArrayBuffer[String]()
val arrbuff2 = ArrayBuffer[String]()
if(js_str1.substring(0,1)=="{" && js_str2.substring(0,1)=="{" || js_str1.substring(0,1)=="["&&js_str2.substring(0,1)=="["){
for(small_js1 <- split_JsonintoSmall(js_str1);small_js2 <- split_JsonintoSmall((js_str2))) {
issame = compare_2Json(small_js1,small_js2)
if(issame == true){
js_str1 = js_str1.substring(0,js_str1.indexOf(small_js1))+js_str1.substring(js_str1.indexOf(small_js1)+small_js1.length)
js_str2 = js_str2.substring(0,js_str2.indexOf(small_js2))+js_str2.substring(js_str2.indexOf(small_js2)+small_js2.length)
}
}
js_str1 = js_str1.substring(1,js_str1.length-1)
js_str2 = js_str2.substring(1,js_str2.length-1)
for(str_js1 <- js_str1.split(","); str_js2 <- js_str2.split(",")){
if(str_js1!="" && str_js2!="")
if(str_js1 == str_js2){
js_str1 = js_str1.substring(0,js_str1.indexOf(str_js1))+js_str1.substring(js_str1.indexOf(str_js1)+str_js1.length)
js_str2 = js_str2.substring(0,js_str2.indexOf(str_js2))+js_str2.substring(js_str2.indexOf(str_js2)+str_js2.length)
}
}
js_str1=js_str1.replace(",","")
js_str2=js_str2.replace(",","")
if(js_str1==""&&js_str2=="")return true
else return false
}
else return false
}
def split_JsonintoSmall(js_str: String):ArrayBuffer[String]={
val arrbuff = ArrayBuffer[String]()
var json_str = js_str
while(json_str.indexOf("{",1)>0 || json_str.indexOf("[",1)>0){
if (json_str.indexOf("{", 1) < json_str.indexOf("[", 1) && json_str.indexOf("{",1)>0 || json_str.indexOf("{", 1) > json_str.indexOf("[", 1) && json_str.indexOf("[",1)<0 ) {
val right = findrealm(1, json_str, '{', '}')
arrbuff += json_str.substring(json_str.indexOf("{", 1), right + 1)
json_str = json_str.substring(0,json_str.indexOf("{",1))+json_str.substring(right+1)
}
else {
if(json_str.indexOf("[",1)>0) {
val right = findrealm(1, json_str, '[', ']')
arrbuff += json_str.substring(json_str.indexOf("[", 1), right + 1)
json_str = json_str.substring(0, json_str.indexOf("[", 1)) + json_str.substring(right + 1)
}
}
}
arrbuff
}
def findrealm(begin_loc: Int, str: String, leftch: Char, rightch: Char): Int = {
var left = str.indexOf(leftch, begin_loc)
var right = str.indexOf(rightch, left)
left = str.indexOf(leftch, left + 1)
while (left < right && left > 0) {
right = str.indexOf(rightch, right + 1)
left = str.indexOf(leftch, left + 1)
}
right
}