Scala convert Seq[Object] to Map[String, Map[String, String]]

Question

I am new to Scala so I am a bit fighting with maps.

I have

val items = Seq[MyModel]

where MyModel (came from Java) contains getLang, getName and getMessage methods.

Now I need to fill up the

var loadedMessagesMap: Map[String, Map[String, String]] = ListMap.empty

to contain values grouped by lang in structure: lang -> (name -> message). Name property is unique. Thank you.

nmat · Accepted Answer · 2017-04-10 23:24:23Z

2

Maybe this will help you:

val result: Map[String, Map[String, Seq[String]]] = items.groupBy(_.getLang).map {
  case(lang, models) =>
    lang -> models.groupBy(_.getName).mapValues(_.map(_.getMessage))
}

It returns a Seq[String] because there might be several messages for the same language and name. Not sure how you want to handle that case.

answered Apr 10, 2017 at 23:24

nmat

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2 Comments

Lukas Jelinek Over a year ago

Thank you. Getting there. I don't need to take care about multiple messages for same lang/name. This case will not happen (and they don't care about that too in FW backend). I did models.groupBy(_.getName).mapValues(_.map(_.getMessage).last) as a third row but I guess it is not the best solution:-)

nmat Over a year ago

@LukasJelinek It's fine. You can use .last or .head to get the a message from the list if you are sure the list will not be empty.

Andrei T. · Accepted Answer · 2017-04-10 23:08:10Z

0

This should do the trick:

val models: Seq[MyModel] = ???
val mapped = models.map { model =>
  model.getLang -> Map(model.getName -> model.getMessage)
}.toMap

I hope this helps you.

edited Apr 10, 2017 at 23:08

answered Apr 10, 2017 at 22:40

Andrei T.

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9 Comments

Lukas Jelinek Over a year ago

Thank you, I am getting there just can you help me how to avoid this? Type mismatch; found : scala.collection.immutable.Map[String,(String, String)], required: Map[String,Map[String,String]]. I need to return the value in: Map[String, Map[String, String]] . Sorry, newbie:-)

Andrei T. Over a year ago

Hmm, so you want also to group by name? You're getting the error because I actually built a map of string to tuples there.

Andrei T. Over a year ago

I edited the answer now, it should do the trick; let me know if that's what you're looking for :)

patrick Over a year ago

Nice. I don't get the comment about replacing (model.getName, model.getMessage) though. Was that re an earlier version of the answer?

Lukas Jelinek Over a year ago

actually it is not necessary to group by name in my case, but the structure is needed in api I need to extend. The modification you did results only in one item, despite I have two models in Seq (same lang, different name and message).

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