[PartialTransformer] Field Option[Field].None to Proto3.Fields.Default

[ps-rterzman]

Hello,
I am trying to use PartialTransfomer for achieving domain to proto3 transfomration.
I faced an issue related to missed fields in domain case class even if proto3 fields are optional with default value.

Domain case class
final case class ClientProductEntity(id: Option[String], promotions: Option[Seq(Promo)], PSCategory: Option[String]) final case class Promo(effectiveStartDate: Option[Long], effectiveEndDate: Option[Long], map: Seq[Map])

Proto3
@SerialVersionUID(0L) final case class ClientProduct( id: _root_.scala.Predef.String = "", releaseDate: _root_.scala.Option[_root_.scala.Long] = _root_.scala.None, promotions: _root_.scala.Seq[com.pricespider.unity.domain.ClientProduct.Promo] = _root_.scala.Seq.empty), pSCategory: _root_.scala.Option[_root_.scala.Predef.String] = _root_.scala.None)

PartialTransformers:
val mappingResult: Either[Result.Errors, ClientProduct] = clientProductEntity .intoPartial[ClientProduct] .withFieldRenamed(_.PSCBID, _.pSCBID) .withFieldRenamed(_.PSCID, _.pSCID) .withFieldRenamed(_.PSCPID, _.pSCPID) .withFieldRenamed(_.PSCategory, _.pSCategory) .withFieldComputed(_.pSPID, from => from.PSPID.orNull) .withFieldConst(_.unknownFields, _root_.scalapb.UnknownFieldSet.empty) .enableOptionDefaultsToNone .transform .asEither .asOption .orNull

mappingResult.right is None
mappingResult.left contains all missed values

I am wondering is there any way to map missed | Option values with default values. Could you help me with that?

[MateuszKubuszok]

With the information code I cannot reproduce anything as I am missing types (Seq[Map], com.pricespider.unity.domain.ClientProduct.Promo), fields (ClientProductEntity has no PSCBID, PSCID) and in general this code doesn't compile (Option[Seq(Promo)] instead of Option[Seq[Promo]]). So I can only guess, what you want to achieve.

From the description, an I can only guess that you wanted to use default values although default values are used when there is no source field, not when the source field is None. There is no support for using default values as None handling, however for this particular case:

implicit val noneIntIsZero: Transformer[Option[Int], Int] = _.getOrElse(0)
implicit val noneLongIsZero: Transformer[Option[Long], Long] = _.getOrElse(0L)
implicit val noneStringIsEmpty: Transformer[Option[String], String] = _.getOrElse("")

clientProductEntity.into[ClientProduct]....transform

would handle most cases.

I don't see how PartialTransformer would be useful here since transformation from a domain model to a Protobuf cannot fail.

[ps-rterzman]

Thank you for your answer.
I tried to use a Transformer instead. Here what I have:
// Convert Option[Seq[A]] to Seq[B] implicit def optionSeqAToSeqB[A, B](implicit aToB: Transformer[A, B]): Transformer[Option[Seq[A]], Seq[B]] = (from) => from.getOrElse(Seq.empty).map(aToB.transform) implicit val optToString: Transformer[Option[String], String] = from => from.getOrElse("") implicit val optToLong: Transformer[Option[Long], Long] = from => from.getOrElse(0L) implicit val optToInt: Transformer[Option[Int], Int] = from => from.getOrElse(0)

I get an error during compilation time:
com.transformer.domain.ClientProduct map: scala.collection.immutable.Seq[com.transformer.domain.ClientProduct.Map] - can't derive transformation from map: scala.Option[scala.collection.immutable.Seq[com.transformer.model.Map]] in source type com.pricespider.unity.model.ClientProductEntity promotions: scala.collection.immutable.Seq[com.transformer.domain.ClientProduct.Promo] - can't derive transformation from promotions: scala.Option[scala.collection.immutable.Seq[com.transformer.model.Promo]] in source type com.pricespider.unity.model.ClientProductEntity

package com.transformer.domain:
`
final case class ClientProductEntity(PSCID: Option[String],
PSCPID: Option[String],
PSPID: Option[String],
PSCBID: Option[String],
name: Option[String],
map: Option[Seq[Map]],
promotions: Option[Seq[Promo]],
releaseDate: Option[root.scala.Long],
createdBy: Option[AuditBy],
revision: Option[Int])

final case class Map(amount: Option[Double], currencyCode: Option[String])
final case class Promo(effectiveStartDate: Option[Long], effectiveEndDate: Option[Long], map: Seq[Map])
final case class AuditBy(source: Option[String], userId: Option[String], traceID: Option[String], spanID: Option[String])`

package com.transformer.model:
`
syntax = "proto3";
option java_package = "com.transformer.domain";

message ClientProduct {
string PSCPID = 1;
string PSPID = 2;
string PSCBID = 3;
string name = 4;
repeated .ClientProduct.Map map = 5;
repeated .ClientProduct.Promo promotions = 6;
optional int64 releaseDate = 7;
.ClientProduct.By createdBy = 8;
int32 revision = 9;
}

message Map {
double amount = 1;
string currencyCode = 2;
}

message Promo {
int64 effectiveStartDate = 1;
optional int64 effectiveEndDate = 2;
repeated .ClientProduct.Map map = 3;
}

message By {
string source = 1;
string userId = 2;
string traceID = 3;
string spanID = 4;
}

@SerialVersionUID(0L) 
final case class ClientProduct(
pSCPID: _root_.scala.Predef.String = "",
pSPID: _root_.scala.Predef.String = "",
pSCBID: _root_.scala.Predef.String = "",
name: _root_.scala.Predef.String = "",
map: _root_.scala.Seq[com.pricespider.unity.domain.ClientProduct.Map] = _root_.scala.Seq.empty,
promotions: _root_.scala.Seq[com.pricespider.unity.domain.ClientProduct.Promo] = _root_.scala.Seq.empty,
releaseDate: _root_.scala.Option[_root_.scala.Long] = _root_.scala.None,
createdBy: _root_.scala.Option[com.pricespider.unity.domain.ClientProduct.By] = _root_.scala.None,
revision: _root_.scala.Int = 0)

  @SerialVersionUID(0L) 
  final case class Map(
  amount: _root_.scala.Double = 0.0,
  currencyCode: _root_.scala.Predef.String = "",
  unknownFields: _root_.scalapb.UnknownFieldSet = _root_.scalapb.UnknownFieldSet.empty
  ) extends scalapb.GeneratedMessage

  
  @SerialVersionUID(0L) 
  final case class Promo(
  effectiveStartDate: _root_.scala.Long = 0L,
  effectiveEndDate: _root_.scala.Option[_root_.scala.Long] = _root_.scala.None,
  map: _root_.scala.Seq[com.pricespider.unity.domain.ClientProduct.Map] = _root_.scala.Seq.empty,
  unknownFields: _root_.scalapb.UnknownFieldSet = _root_.scalapb.UnknownFieldSet.empty
  ) extends scalapb.GeneratedMessage
  
  @SerialVersionUID(0L) 
  final case class By(
  source: _root_.scala.Predef.String = "",
  userId: _root_.scala.Predef.String = "",
  traceID: _root_.scala.Predef.String = "",
  spanID: _root_.scala.Predef.String = "",
  unknownFields: _root_.scalapb.UnknownFieldSet = _root_.scalapb.UnknownFieldSet.empty
  ) extends scalapb.GeneratedMessage

`
P.S. I am really sorry about code formatting. I tried to do my best.

[MateuszKubuszok]

Sorry for the late reply.

You error is:

com.transformer.domain.ClientProduct
  map: scala.collection.immutable.Seq[com.transformer.domain.ClientProduct.Map] - can't derive transformation from map: scala.Option[scala.collection.immutable.Seq[com.transformer.model.Map]] in source type com.pricespider.unity.model.ClientProductEntity
  promotions: scala.collection.immutable.Seq[com.transformer.domain.ClientProduct.Promo] - can't derive transformation from promotions: scala.Option[scala.collection.immutable.Seq[com.transformer.model.Promo]] in source type com.pricespider.unity.model.ClientProductEntity

The issue is here:

implicit def optionSeqAToSeqB[A, B](implicit aToB: Transformer[A, B]): Transformer[Option[Seq[A]], Seq[B]] =
  (from) => from.getOrElse(Seq.empty).map(aToB.transform)

due to specifics of how derivation in Chimney works your code does not call a macro recursively. You'd have to modify your code to:

implicit def optionSeqAToSeqB[A, B](implicit aToB: Transformer.AutoDerived[A, B]): Transformer[Option[Seq[A]], Seq[B]] =
  (from) => from.getOrElse(Seq.empty).map(aToB.transform)

then macro could derive Transformer.AutoDerived[A, B], this implicit would find it, and macro would find this implicit.