Smithy and Scarango

[zetashift]

So for a personal project I'm using ArangoDB(it's like DynamoDB but with graphs) and the scala driver https://github.com/outr/scarango

A Document in scarango is defined for example as follow(from the README):

// Case class to represent a person collection
case class Person(name: String, age: Int, _id: Id[Person] = Person.id()) extends Document[Person]

// We use the companion object to represent additional information about the collection
object Person extends DocumentModel[Person] {
  override implicit val rw: RW[Person] = ccRW

  val name: Field[String] = field("name")
  val age: Field[Int] = field("age")

  override def indexes: List[Index] = List(
    name.index.persistent()
  )

  override val collectionName: String = "people"
}

// We represent our entire database here referencing all collections
object Database extends Graph("example") {
  val people: DocumentCollection[Person] = vertex[Person](Person)
}

So I have made a Person API where smithy4s generates the case classes, but I'd need some way to this generated person to be a Document[Person] and DocumentModel[Person].
What would a nice way to do this be?

I guess this is more a Scala than a smithy question, so sorry if this is the wrong place to ask! I also tried reading this part : https://blog.indoorvivants.com/2022-06-11-smithy4s-fullstack-part-2#codecs
On how to go from model -> db codec but as a complete noob I didn't really understand it well ><

[kubukoz]

I think you won't be able to make the generated class extend Document[Person] directly, but you might be able to make an implicit conversion for that.

For DocumentModel[Person], I'd advise you to try and implement SchemaVisitor[DocumentModel]. Still, even if it's possible, you won't be able to call e.g. Person.name.

This might fall out of scope for Smithy4s usage. We don't provide this level of customization of the generated code, and as far as I know it's not likely to change.

[zetashift]

Yea I totally get understand that it falls out of scope for smithy4s! I was just wondering what a nice way to encode them would be :P
I'll look into the implicit conversion and the SchemaVisitor thing, thank you.

[Baccata]

@kubukoz is correct in that this falls out of the scope of Smithy4s. You'd have to create you own code-generator for this, we're not really intending on making ours customisable, in the near/medium term anyway.

Jakub is also right in that it may be possible to get derive a fabric.rw.RW from smithy4s schemas, via a smithy4s.schema.SchemaVisitor. All data types generated are accompanied by a "schema" which allows for introspecting their structures. That's how Smithy4s decouples the generated code from specific formats and libraries.

But besides that, it looks like scarango has a lot of D <: Document[D] type constraints, which implies that it can only work with datatypes that extend their Document types, which is not something that Smithy4s can do, I'm afraid.

[Baccata]

That being said, Smithy makes it reasonably easy to create code generators on top of it, so you could have a bespoke code generator tool that'd interop with Scarango. Obviously this is a reasonably large investment compared to what you were probably hoping to find

[zetashift]

Thanks for the thoughtful answers! The whole SchemaVisitor and a bespoke tool seems a bit too difficult for me, but since this is all for a personal project, I might try and see if I can learn a thing or two.