Supports snakecase.(Using regex)

src/main/scala/spray/json/SnakeCaseJsonSupport.scala

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+/**
+  * The MIT License (MIT)
+  *
+  * Copyright (c) 2013-2015 Andrew Snare, Age Mooij
+  *
+  * Permission is hereby granted, free of charge, to any person obtaining a copy
+  * of this software and associated documentation files (the "Software"), to deal
+  * in the Software without restriction, including without limitation the rights
+  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+  * copies of the Software, and to permit persons to whom the Software is
+  * furnished to do so, subject to the following conditions:
+  *
+  * The above copyright notice and this permission notice shall be included in all
+  * copies or substantial portions of the Software.
+  *
+  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+  * SOFTWARE.
+  */
+package spray.json
+
+/**
+  * A custom version of the Spray DefaultJsonProtocol with a modified field naming strategy
+  */
+trait SnakeCaseJsonSupport extends DefaultJsonProtocol {
+  import reflect._
+
+  /**
+    * This is the most important piece of code in this object!
+    * It overrides the default naming scheme used by spray-json and replaces it with a scheme that turns camelcased
+    * names into snakified names (i.e. using underscores as word separators).
+    */
+  override protected def extractFieldNames(classTag: ClassTag[_]) = {
+    import java.util.Locale
+
+    def snakify(name: String) = PASS2.replaceAllIn(PASS1.replaceAllIn(name, REPLACEMENT), REPLACEMENT).toLowerCase(Locale.US)
+
+    super.extractFieldNames(classTag).map { snakify(_) }
+  }
+
+  private val PASS1 = """([A-Z]+)([A-Z][a-z])""".r
+  private val PASS2 = """([a-z\d])([A-Z])""".r
+  private val REPLACEMENT = "$1_$2"
+}
+
+object SnakeCaseJsonSupport extends SnakeCaseJsonSupport
+

src/test/scala/spray/json/SnakeCaseJsonSupportSpec.scala

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+package spray.json
+
+import org.specs2.mutable._
+
+class SnakeCaseJsonSupportSpec extends Specification with SnakeCaseJsonSupport {
+
+  "SnakeCaseJsonSupport" should {
+    "convert field names to snake cased fields names." in {
+      // Given
+      case class SampleFields(
+          HelloWorld: Int = 0,
+          A1AAbBBBBBbCCcc: Int = 0,
+          AbAAbbAAAbbb1AA2bb1AA2AAAAbb1bAA: Int = 0,
+          x: Int = 0,
+          Y: Int = 0,
+          `^There-arE_Non_(Alphabetic))_character!S`: Int = 0,
+          `tHere-Are_(AlsO)_noN_(alphaBetic))_CharaCter!s`: Int = 0,
+          `  There are space character `: Int = 0,
+          ` これは　マルチバイトAbcのaBc確認です。`: Int = 0,
+          ab: Int = 0,
+          AC: Int = 0,
+          Ad: Int = 0,
+          bA: Int = 0,
+          AAA: Int = 0,
+          AAb: Int = 0,
+          AbA: Int = 0,
+          bAA: Int = 0,
+          bbA: Int = 0,
+          bAb: Int = 0,
+          Acc: Int = 0,
+          ccc: Int = 0
+      )
+      case class SampleFields2(
+          aaa123bbb: Int = 0,
+          aaA123bbb: Int = 0,
+          aaa123Bbb: Int = 0,
+          aaA123Bbb: Int = 0,
+          aaa123: Int = 0,
+          aaA123: Int = 0,
+          aAA123: Int = 0
+      )
+      implicit val jsonFormat1: RootJsonFormat[SampleFields] =
+         jsonFormat21(SampleFields.apply)
+      implicit val jsonFormat2: RootJsonFormat[SampleFields2] =
+        jsonFormat7(SampleFields2.apply)
+      // When
+      val sampleFields1 = SampleFields().toJson.asJsObject
+      val sampleFields2 = SampleFields2().toJson.asJsObject
+      // Then
+      val fields1 = sampleFields1.fields
+      fields1 must haveKey ("hello_world")
+      fields1 must haveKey ("a1_a_ab_bbbb_bb_c_ccc")
+      fields1 must haveKey ("ab_a_abb_aa_abbb1_aa2bb1_aa2_aaa_abb1b_aa")
+      fields1 must haveKey ("x")
+      fields1 must haveKey ("y")
+      fields1 must haveKey ("^there-ar_e_non_(alphabetic))_character!s")
+      fields1 must haveKey ("t_here-are_(als_o)_no_n_(alpha_betic))_chara_cter!s")
+      fields1 must haveKey ("  there are space character ")
+      fields1 must haveKey (" これは　マルチバイトabcのa_bc確認です。")
+      fields1 must haveKey ("ab")
+      fields1 must haveKey ("ac")
+      fields1 must haveKey ("ad")
+      fields1 must haveKey ("b_a")
+      fields1 must haveKey ("aaa")
+      fields1 must haveKey ("a_ab")
+      fields1 must haveKey ("ab_a")
+      fields1 must haveKey ("b_aa")
+      fields1 must haveKey ("bb_a")
+      fields1 must haveKey ("b_ab")
+      fields1 must haveKey ("acc")
+      fields1 must haveKey ("ccc")
+      val fields2 = sampleFields2.fields
+      fields2 must haveKey("aaa123bbb")
+      fields2 must haveKey("aa_a123bbb")
+      fields2 must haveKey("aaa123_bbb")
+      fields2 must haveKey("aa_a123_bbb")
+      fields2 must haveKey("aaa123")
+      fields2 must haveKey("aa_a123")
+      fields2 must haveKey("a_aa123")
+    }
+    "deserialize snake cased json" in {
+      // Given
+      case class SampleFields(
+          a: Int,
+          aA: Int,
+          helloWorld: Int,
+          HelloTheWorld: Int
+      )
+      implicit val jsonFormat: RootJsonFormat[SampleFields] =
+        jsonFormat4(SampleFields.apply)
+      val json = JsObject(
+        "hello_the_world" -> 4.toJson,
+        "a_a" -> 2.toJson,
+        "a" -> 1.toJson,
+        "hello_world" -> 3.toJson
+      )
+      // When
+      val result = jsonFormat.read(json)
+      // Then
+      result mustEqual SampleFields(
+        a = 1, aA = 2, helloWorld = 3, HelloTheWorld = 4
+      )
+    }
+  }
+}