Scala: remove field from json files in the nested object with defined name

问题

I'm new to scala. I'm trying to make simple manipulations with json files. I'm stucked with the following task: how can I ellegant remove field with defined name within object with defined name. As an example I'd like to delete dsc1 field from the object name2

{
  "group": {
    "name1":{
      "dsc":"some dsc",
      "dsc1":"some dsc",
      "dsc2":"some dsc"
     },
    "name2":{
      "dsc":"some dsc",
      "dsc1":"some dsc",
      "dsc2":"some dsc"
    }
  }
}

For parsing I'm using liftweb. I've cteate the following code but it deletes all dsc1:

val transformedJson2 = parsedInput transform { 
    case JObject(fields) if (fields.head.name == "name2") => JObject(fields) transform {
          case JField("dsc1", JArray(xs)) =>  JNothing
}

回答1:

I rewrote your transformation a little bit, and this seemed to worked when I tried it against your input:

val transformedJson2 = parsedInput transform { 
  case JField("name2", fields) => 
    fields remove {
      case JField("dsc1", _) =>  true
      case _ => false   
    }
}

Instead of using remove, you could also use a second transform as you did in your example:

val transformedJson2 = parsedInput transform { 
  case JField("name2", fields) => 
    fields transform {
      case JField("dsc1", _) =>  JNothing
    }
}

So, by using the parsed input from:

scala> val parsedInput = parse(""" {
     |   "group": {
     |     "name1":{
     |       "dsc":"some dsc",
     |       "dsc1":"some dsc",
     |       "dsc2":"some dsc"
     |      },
     |     "name2":{
     |       "dsc":"some dsc",
     |       "dsc1":"some dsc",
     |       "dsc2":"some dsc"
     |     }
     |   }
     | } """)
parsedInput: net.liftweb.json.package.JValue = JObject(List(JField(group,JObject(List(JField(name1,JObject(List(JField(dsc,JString(some dsc)), JField(dsc1,JString(some dsc)), JField(dsc2,JString(some dsc))))), JField(name2,JObject(List(JField(dsc,JString(some dsc)), JField(dsc1,JString(some dsc)), JField(dsc2,JString(some dsc))))))))))

Both should yield the output:

scala> pretty(render(transformedJson2))
res10: String = 
{
  "group":{
    "name1":{
      "dsc":"some dsc",
      "dsc1":"some dsc",
      "dsc2":"some dsc"
    },
    "name2":{
      "dsc":"some dsc",
      "dsc2":"some dsc"
    }
  }
}

回答2:

I tried this:

 val transformedJson2 = parsedInput transformField {
    case JField("group", fields) => (
      "group", fields transformField {
         case JField("name2", nameFields) => ( 
             "name2", nameFields removeField {
               case JField("dsc1", _) => true    
               case _ => false
             }
         )
      }     
    )
}

println(compact(render(transformedJson2)))

来源：https://stackoverflow.com/questions/14216069/scala-remove-field-from-json-files-in-the-nested-object-with-defined-name

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json

scala

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