validateEveryToJSON wants ToJSON even for ReqBody

[jonathanjouty]

With the following API

type UserAPI
  = (Capture "user_id" UserId :> Get '[JSON] User)
  :<|> (Capture "new" :> ReqBody '[JSON] NewUser :> Post '[JSON] UserId)

and only the following instances

newtype UserId = ...
instance FromHttpApiData UserId
instance ToJSON UserId

data User = ...
instance ToJSON User

data NewUser = ...
instance FromJSON NewUser

It is not possible to use validateEveryToJSON because it expects instance ToJSON NewUser even though the UserAPI is perfectly usable as NewUser is only used in ReqBody and thus only requires a FromJSON instance.

Of course an easy fix is to just add a ToJSON instance, which is low risk compared to adding FromJSON instances for things you only want to send out.

[jonathanjouty]

Looks like changing BodyTypes is actually relatively easy, but swagger2 only has validateToJSON and not validateFromJSON.

Seems like implementation was started though: https://github.com/GetShopTV/swagger2/pull/162

[jonathanjouty]

Excuse that, I'm blind! The PR was merged and the function exists: https://hackage.haskell.org/package/swagger2-2.3.1.1/docs/Data-Swagger-Schema-Generator.html#v:validateFromJSON