qingwei91/apigen

Generate Scala Server Client stub from OpenAPI

Goal

• Able to model OpenApi v3 as AST in Scala
• Able to convert AST to http4s code (code gen)

Implementation plan

Milestone 1: Able to convert petstore.yml to model classes Milestone 2: Able to convert petstore.yml to Http4s routes Milestone 3: Able to convert petstore.yml to Sttp Client code

How to work with this project?

This project contains 3 parts:

1. core - contains code to convert an OpenApi spec file into scala AST
2. sbt-apigen - wrap core into a sbt plugin, exposes some settings
3. example - a test project to test sbt-apigen

To develop, this is what I do:

1. Make change in core/sbt-apigen
2. compile and run publishLocal from root project, this will publish SNAPSHOT version of sbt-apigen
3. Start sbt session in example project, and compile, then you can find generated code in example/target/scala-2.12/src_managed/codegen/generated.scala

For some reason, Intellij does not understand the generated code in example project

Things I've learned

1. scala meta is awesome, thanks Olaf!
2. when you feel you need some sort of control inversion, eg. passing context through multiple layers to control a behaviour down the call chain, consider model your call-chain as function where the param is 1st class citizen, then each layer can now read context from caller, and decide context for callee, in a principled way

Todo

• use iota's coproduct instead of sealed trait (sealed trait is not open and does not faithfully represent the idea in open api spec)