how to parse a complicated json in Scala - json

Question

I am a real newbie in Scala (Using Play framework) and trying to figure out what would be the best way to parse a complicated JSON.
This is an example I have:
{
"id":"test1",
"tmax":270,
"at":2,
"bcat":[
"IAB26",
"IAB25",
"IAB24"
],
"imp":[
{
"id":"1",
"banner":{
"w":320,
"h":480,
"battr":[
10
],
"api":[
]
},
"bidfloor":0.69
}
],
"app":{
"id":"1234",
"name":"Video Games",
"bundle":"www.testapp.com",
"cat":[
"IAB1"
],
"publisher":{
"id":"1111"
}
},
"device":{
"dnt":0,
"connectiontype":2,
"carrier":"Ellijay Telephone Company",
"dpidsha1":"e5f61ae0597d8abee94860d66f7d512aa68d0985",
"dpidmd5":"c1827fe90bae819017dfdb30db7e84fa",
"didmd5":"1f6cb9dc519db8e48cf9592b31cce04e",
"didsha1":"2e6a5d7f5fd1b2b5dea56a80f2b9dc24902a0ca7",
"ifa":"422aeb3a-6507-40b5-9e6f-42a0e14b51be",
"osv":"4.4",
"os":"Android",
"ua":"Mozilla/5.0 (Linux; Android 4.4.2; DL1010Q Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Safari/537.36",
"ip":"24.75.160.74",
"devicetype":1,
"geo":{
"type":1,
"country":"USA",
"city":"Jasper"
}
},
"user":{
"id":"9c2be7c2a3dfe19070f193910e92b2e0"
},
"cur":[
"USD"
]
}
Thank you very much!

Answer 1

I would go with case classes as described in http://json4s.org/#extracting-values e.g.
scala> import org.json4s._
scala> import org.json4s.jackson.JsonMethods._
scala> implicit val formats = DefaultFormats // Brings in default date formats etc.
scala> case class Child(name: String, age: Int, birthdate: Option[java.util.Date])
scala> case class Address(street: String, city: String)
scala> case class Person(name: String, address: Address, children: List[Child])
scala> val json = parse("""
{ "name": "joe",
"address": {
"street": "Bulevard",
"city": "Helsinki"
},
"children": [
{
"name": "Mary",
"age": 5,
"birthdate": "2004-09-04T18:06:22Z"
},
{
"name": "Mazy",
"age": 3
}
]
}
""")
scala> json.extract[Person]
res0: Person = Person(joe,Address(Bulevard,Helsinki),List(Child(Mary,5,Some(Sat Sep 04 18:06:22 EEST 2004)), Child(Mazy,3,None)))

Answer 2

Use implicit to automatically fetch json value with the same name.
if you have a string like
val jsonString =
{ "company": {
"name": "google",
"department": [
{
"name": "IT",
"members": [
{
"firstName": "Max",
"lastName": "Joe",
"age" : 25
},
{
"firstName": "Jean",
"lastName": "Nick",
"age" : 55,
"salary": 100,000
}
]
},
{
"name": "Marketing"
"members": [
{
"firstName": "Mike",
"lastName": "Lucas",
"age" : 43
}
]
},
]
}
}
Then we should do as following to parse it into scala object
val json: JsValue = Json.parse(jsonString) // string to JsValue
case class Person(firstName: String, lastName: String, age: Int, salary: Option[Int]) // keep the lower level object above since you will use them below
implicit personR = Json.reads[Person]
// implicit will read the json attribute if you use the same name as it is in json String. For example "name" : "google" will be read if you have Company(name: String). See the "name" and name:String .
case class Department(name: String, members: Seq[Person])
implicit departmentR = Json.reads[Department]
case class Company(name: String, department: Seq[Department])
implicit val companyR = Json.reads[Company]
val result = json.validate[Company] match {
case s: JsSuccess[Company] => s.get // s.get will return a Company object
case e: JsError => println("error")
}

Answer 3

Don't know if it can be used standalone, but Play Framework has great tools to work with JSON. Take a look here