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@maji-KY
Created October 18, 2014 13:43
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json4sでcase classをJSONにシリアライズするときにキーをスネークケースにしたい
import org.json4s.jackson.{JsonMethods, Serialization}
import org.json4s.{Extraction, Formats, NoTypeHints}
object JsonTest extends App {
// Extraction.decomposeでJSON ASTを組み立てている
// んで、それにはsnakizeKeysってメソッドがあるのでそれを使えばスネークケースになる
def myWrite[A <: AnyRef](a: A)(implicit formats: Formats): String = JsonMethods.mapper.writeValueAsString(Extraction.decompose(a)(formats).snakizeKeys)
// プリティ☆バージョン
def myWritePretty[A <: AnyRef](a: A)(implicit formats: Formats): String = JsonMethods.mapper.writerWithDefaultPrettyPrinter.writeValueAsString(Extraction.decompose(a)(formats).snakizeKeys)
case class FooClass(someValue: String, nestedMap: Map[String, String])
val foo = FooClass("Hello World", Map("fooBarBaz" -> "fooBarBaz", "StringMessage" -> "hello"))
implicit val formats = Serialization.formats(NoTypeHints)
println(myWritePretty(foo))
/*
以下が結果。
Mapの中身のStringのキーも変換される。
{
"some_value" : "Hello World",
"nested_map" : {
"foo_bar_baz" : "fooBarBaz",
"string_message" : "hello"
}
}
*/
}
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