Swagger-codegen: [FINCH] no enum support

[daniele-bettella]

Description

The Finch code generator does not support enums. An inline enum generates a normal variable of the desired type; a referenced enum generates an empty case class.

Swagger-codegen version

2.2.2-SNAPSHOT

Swagger declaration file content or url

      resultCode:
        type: string
        enum: [
          "OK",
          "EXCEPTION",
          "BAD_REQUEST"
        ]

Suggest a Fix

As far as I know there is no single best implementation choice for enumerations in scala. Possible choices are:

• scala enumeration class (no warning for non-exhaustive match, type erasure issues)
• sealed case objects (no easy way of iterating through values, no default serialization / deserialization)
  The serialization issue might not be a problem if circe supports it; still, scala enumerations might be easier to implement.

[wing328]

@daniele-bettella thanks for reporting the issue.

akka-scala generator has better support for enum:

swagger-codegen|master⚡ ⇒ grep -R -i enum modules/swagger-codegen/src/main/resources/akka-scala/*
modules/swagger-codegen/src/main/resources/akka-scala/enumsSerializers.mustache:object EnumsSerializers {
modules/swagger-codegen/src/main/resources/akka-scala/enumsSerializers.mustache:  def all = Seq[Serializer[_]](){{#models}}{{#model}}{{#hasEnums}}{{#vars}}{{#isEnum}} :+
modules/swagger-codegen/src/main/resources/akka-scala/enumsSerializers.mustache:    new EnumNameSerializer({{classname}}Enums.{{datatypeWithEnum}}){{/isEnum}}{{/vars}}{{/hasEnums}}{{/model}}{{/models}}
modules/swagger-codegen/src/main/resources/akka-scala/enumsSerializers.mustache:  private class EnumNameSerializer[E <: Enumeration: ClassTag](enum: E)
modules/swagger-codegen/src/main/resources/akka-scala/enumsSerializers.mustache:    val EnumerationClass = classOf[E#Value]
modules/swagger-codegen/src/main/resources/akka-scala/enumsSerializers.mustache:      case (t @ TypeInfo(EnumerationClass, _), json) if isValid(json) => {
modules/swagger-codegen/src/main/resources/akka-scala/enumsSerializers.mustache:            enum.withName(value)
modules/swagger-codegen/src/main/resources/akka-scala/enumsSerializers.mustache:            throw new MappingException(s"Can't convert $value to $EnumerationClass")
modules/swagger-codegen/src/main/resources/akka-scala/enumsSerializers.mustache:      case JString(value) if enum.values.exists(_.toString == value) => true
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:  {{{name}}}: {{^required}}Option[{{/required}}{{^isEnum}}{{datatype}}{{/isEnum}}{{#isEnum}}{{classname}}Enums.{{datatypeWithEnum}}{{/isEnum}}{{^required}}]{{/required}}{{#hasMore}},{{/hasMore}}
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:{{#hasEnums}}
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:object {{classname}}Enums {
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:  {{#isEnum}}
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:  type {{datatypeWithEnum}} = {{datatypeWithEnum}}.Value
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:  {{/isEnum}}
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:  {{#isEnum}}
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:  object {{datatypeWithEnum}} extends Enumeration {
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:{{#_enum}}
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:    val {{#fnEnumEntry}}{{.}}{{/fnEnumEntry}} = Value("{{.}}")
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:{{/_enum}}
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:  {{/isEnum}}
modules/swagger-codegen/src/main/resources/akka-scala/model.mustache:{{/hasEnums}}

Maybe we can reuse these for other scala-related generators.

cc @clasnake

[clasnake]

@wing328 Yep. Had a quick look and akka-scala uses the Enumeration class to implement this. I can try reusing this in the finch generator and other scala related generator.

[jimschubert]

@clasnake @wing328 @daniele-bettella For finch, we'll probably also need to consider compile-time serializers like circe or argonuat.

[erikwj]

@daniele-bettella are you working on this? I had the same idea and thought about using this https://github.com/julienrf/enum