Customizations

An example demo is available demonstrating substantial customization of these concepts for the purposes of data validation: Alkimi Exchange Demo — this can provide some clarity as to one form of extensions of these methods beyond a simple currency application.

Within this, we see an example of customized API endpoints following these conventions where we are using a custom data type representing a non-standard transaction format:

case request @ POST -> Root / "data-transactions" / "sign" =>
      val lastSnapshotHash = request.params.get("lastSnapshotHash").fold(Hash.empty)(Hash(_))

      def dataTransactionsFromRequest() =
        request
          .attemptAs[DataTransaction]
          .toOption
          .fold(request.as[List[DataTransaction]])(t => List(t).pure)
          .flatten

This endpoint is used for signing non-currency transaction data for preparation to addition to a consensus stage with a custom validation criteria.

The validator in this case is quite simple, and just checks if the string length is greater than some value:

  private [validators] def validateOne(dataTransaction : DataTransaction): ValidatedNec[DataTransactionValidationError, DataTransaction] = {
    val validatedLength: Either[DataTransactionValidationError, DataTransaction] =
      if (dataTransaction.txnid.length > 5) Right(dataTransaction)
      else Left(DataTransactionValidationError(s"txnid length must be greater than 5 but was ${dataTransaction.txnid}"))

    val validatedData1: Either[DataTransactionValidationError, DataTransaction] =
      if (dataTransaction.data1 > 0) Right(dataTransaction)
      else Left(DataTransactionValidationError(s"data1 must be greater than 0 but was ${dataTransaction.data1}"))

    validatedLength.toValidatedNec.productR(validatedData1.toValidatedNec)
  }