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

北慕城南 提交于 2019-12-22 13:45:37

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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