I try to get the image url of the first object tha...

# stdlib

[Simon Schubert]

I try to get the image url of the first object that exist in the database based on a list of object ids. My current solution looks like the following:

var ids = listOf("123", "456", ...)
var imageUrl = getFirstImageUrl(ids)

fun getFirstImageUrl(list: List<String>): String? { 
    list.forEach {
       var item = database.getItemById(it)
       if(item != null) {
          return item.imageUrl
       }
    }
    return null
}

Is there a better way to do it in kotlin? I could image a solution something like this:

var imageUrl = ids.firstNotNullFlat {
  var item = database.getItemById(it)
  item?.imageUrl
}

[spand]

A less imperative way would be to use a Sequence, map id to imageUrl, call firstOrNull to search for first not null

[Simon Schubert]

Like this?

val imageUrl = ids.asSequence().map { database.getItemById(it)?.imageUrl }.firstOrNull()

It returns the imageUrl of the first found item in the database and stops iterating over the remaining ids right?

[spand]

I believe that is the general idea of sequences

[spand]

Havent used them myself much

[Simon Schubert]

Smart sequences 💡 Thanks a lot, I haven't really used them myself too.

[Pavlo Liapota]

You need to call firstOrNull { it != null } .
Alternatively you can write:
mapNotNull { ... }.firstOrNull()

[Simon Schubert]

@Pavlo Liapota thanks a lot