json4s | 易学教程

Json4s ignoring None fields during seriallization (instead of using 'null')

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问题 I am having a generic json serialization method that uses json4s . Unfortunately, it is ignoring fields if the value is None . My goal is to have None fields be represented with a null value. I tried by adding custom serializer for None, but still it is not working. object test extends App { class NoneSerializer extends CustomSerializer[Option[_]](format => ( { case JNull => None }, { case None => JNull })) implicit val f = DefaultFormats + new NoneSerializer case class JsonTest(x: String, y:

Deserialization of case object in Scala with JSON4S

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问题 I have some case classes defined like follows: sealed trait Breed case object Beagle extends Breed case object Mastiff extends Breed case object Yorkie extends Breed case class Dog(name: String, breed: Breed) I also have an endpoint defined with Scalatra: post("/dog") { val dog = parsedBody.extract[Dog] ... } I'd like this JSON object: { name: "Spike", breed: "Mastiff" } to deserialize to the appropriate instance of Dog . I'm struggling to figure out how to write a custom deserializer for

Akka实战：构建REST风格的微服务

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使用Akka-Http构建REST风格的微服务，服务API应尽量遵循REST语义，数据使用JSON格式交互。在有错误发生时应返回： {"errcode":409,"errmsg":"aa is invalid，the ID is expected to be bb"} 类似的JSON错误消息。代码： https://github.com/yangbajing/akka-action http://git.oschina.net/yangbajing/akka-action 代码首先来看看代码文件结构： ├── ApiRoute.scala ├── App.scala ├── ContextProps.scala ├── book │ ├── Book.scala │ ├── BookContextProps.scala │ ├── BookRoute.scala │ └── BookService.scala └── news ├── News.scala ├── NewsContextProps.scala ├── NewsRoute.scala └── NewsService.scala 通过名字可以看出， App.scala 是启动程序，以 Route 结尾的是API路由定义文件， Service 结尾的就是服务实现代码了。 ContextProps

How to convert Row to json in Spark 2 Scala

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问题 Is there a simple way to converting a given Row object to json? Found this about converting a whole Dataframe to json output: Spark Row to JSON But I just want to convert a one Row to json. Here is pseudo code for what I am trying to do. More precisely I am reading json as input in a Dataframe. I am producing a new output that is mainly based on columns, but with one json field for all the info that does not fit into the columns. My question what is the easiest way to write this function:

Map[String,Any] to compact json string using json4s

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问题 I am currently extracting some metrics from different data sources and storing them in a map of type Map[String,Any] where the key corresponds to the metric name and the value corresponds to the metric value. I need this to be more or less generic, which means that values types can be primitive types or lists of primitive types. I would like to serialize this map to a JSON-formatted string and for that I am using json4s library. The thing is that it does not seem possible and I don't see a

Is it possible to use json4s 3.2.11 with Spark 1.3.0?

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问题 Spark has a dependency on json4s 3.2.10, but this version has several bugs and I need to use 3.2.11. I added json4s-native 3.2.11 dependency to build.sbt and everything compiled fine. But when I spark-submit my JAR it provides me with 3.2.10. build.sbt import sbt.Keys._ name := "sparkapp" version := "1.0" scalaVersion := "2.10.4" libraryDependencies += "org.apache.spark" %% "spark-core" % "1.3.0" % "provided" libraryDependencies += "org.json4s" %% "json4s-native" % "3.2.11"` plugins.sbt