如何使用使用蛇案(下划线表示法)而不是骆驼案的Spray JSON解析JSON [英] How to parse json with spray json that uses snake case (underscore notation) instead of camel case

问题描述

如何使用使用蛇形(下划线表示法)而不是驼峰式的spray json解析json?

How to parse json with spray json that uses snake case (underscore notation) instead of camel case?

例如

case class Test(subjectDescription: String)
"{\"subject_description\":\"Medicine\"}".parseJson.convertTo[Test]

应该工作，并且不会引发异常.

should work and not throw exception.

推荐答案

此答案来自 https://groups.google.com/forum/#!msg/spray-user/KsPIqWDK0AY/HcanflgRzMcJ .由于SEO更好，因此将其放在SO上.

This answer is taken from https://groups.google.com/forum/#!msg/spray-user/KsPIqWDK0AY/HcanflgRzMcJ. Putting it on SO since the SEO is better.

/**
 * A custom version of the Spray DefaultJsonProtocol with a modified field naming strategy
 */
trait SnakifiedSprayJsonSupport 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 SnakifiedSprayJsonSupport extends SnakifiedSprayJsonSupport

import SnakifiedSprayJsonSupport._

object MyJsonProtocol extends SnakifiedSprayJsonSupport {
  implicit val testFormat = jsonFormat1(Test.apply)
}

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