Parsing bad Json in Scala - json

Question

I'm trying to parse some problematic Json in Scala using Play Json and using implicit, but not sure how to proceed...
The Json looks like this:
"rules": {
"Some_random_text": {
"item_1": "Some_random_text",
"item_2": "text",
"item_n": "MoreText",
"disabled": false,
"Other_Item": "thing",
"score": 1
},
"Some_other_text": {
"item_1": "Some_random_text",
"item_2": "text",
"item_n": "MoreText",
"disabled": false,
"Other_Item": "thing",
"score": 1
},
"Some_more_text": {
"item_1": "Some_random_text",
"item_2": "text",
"item_n": "MoreText",
"disabled": false,
"Other_Item": "thing",
"score": 1
}
}
I'm using an implicit reader but because each top level item in rules is effectively a different thing I don't know how to address that...
I'm trying to build a case class and I don't actually need the random text heading for each item but I do need each item.
To make my life even harder after these items are lots of things in other formats which I really don't need. They are unnamed items which just start:
{
random legal Json...
},
{
more Json...
}
I need to end up with the Json I'm parsing in a seq of case classes.
Thanks for your thoughts.

Answer 1

I'm using an implicit reader but because each top level item in rules is effectively a different thing I don't know how to address that...
Play JSON readers depend on knowing names of fields in advance. That goes for manually constructed readers and also for macro generated readers. You cannot use an implicit reader in this case. You need to do some traversing first and extract pieces of Json that do have regular structure with known names and types of fields. E.g. like this:
case class Item(item_1: String, item_2: String, item_n: String, disabled: Boolean, Other_Item: String, score: Int)
implicit val itemReader: Reads[Item] = Json.reads[Item]
def main(args: Array[String]): Unit = {
// parse JSON text and assume, that there is a JSON object under the "rules" field
val rules: JsObject = Json.parse(jsonText).asInstanceOf[JsObject]("rules").asInstanceOf[JsObject]
// traverse all fields, filter according to field name, collect values
val itemResults = rules.fields.collect {
case (heading, jsValue) if heading.startsWith("Some_") => Json.fromJson[Item](jsValue) // use implicit reader here
}
// silently ignore read errors and just collect sucessfully read items
val items = itemResults.flatMap(_.asOpt)
items.foreach(println)
}
Prints:
Item(Some_random_text,text,MoreText,false,thing,1)
Item(Some_random_text,text,MoreText,false,thing,1)
Item(Some_random_text,text,MoreText,false,thing,1)