Object and primitive as parameter cause type mismatch

[timo-a]

When I generate the following schema which is valid according to https://apitools.dev/swagger-parser/online/:

openapi: 3.0.1
info:
  title: heterogenous params bug report
  version: 0.0.0
paths:
  /debug/stepPolarSession{foo}/{ba}:
    post:
      tags:
      - error-repro
      operationId: reproduceBbug
      parameters:
      - name: foo
        in: path
        required: true
        schema:
          $ref: '#/components/schemas/Cat'
      - name: ba
        in: path
        required: true
        schema:
          type: integer
          format: int32
      responses:
        "200":
          description: OK
          content:
            '*/*':
              schema:
                $ref: '#/components/schemas/Cat'
components:
  schemas:
    Cat:
      required:
      - theta
      type: object
      properties:
        theta:
          type: number
          format: double

I get an error when makeing it:

Detected problems in 1 module.
-- TYPE MISMATCH ---------------------- generated/src/Api/Request/ErrorRepro.elm

The 2nd element of this list does not match all the previous elements:

34|         [ ( "foo",  foo_path ), ( "ba", String.fromInt ba_path ) ]
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The 2nd element is a tuple of type:

    ( String, String )

But all the previous elements in the list are:

    ( String, Api.Data.Cat )

Hint: Everything in a list must be the same type of value. This way, we never
run into unexpected values partway through a List.map, List.foldl, etc. Read
<https://elm-lang.org/0.19.1/custom-types> to learn how to “mix” types.

I use java -jar openapi-generator-cli-5.0.0-20201029.041527-838.jar generate -g elm -i spec.yaml -o generated for generation and elm make src/Main.elm for building.

[eriktim]

Thanks for reporting this @timo-a. This is currently indeed not supported. My first question would be: what would this request look like? And what would it mean to send your Cat like this?

[timo-a]

I've updated the path, now editor.swagger.io generates a nice ui:
https://editor.swagger.io/?_ga=2.21309560.256213889.1605133114-1775662374.1604335444

I was fiddling around (writing a server, generating api spec, updating my elm client), when I came across this. Thinking about it, it is probably not a very common use case as the cat would most likely be sent via the body. To make this work you would probably have to covert foo_path to string in:

reproduceBbug : Api.Data.Cat -> Int -> Api.Request Api.Data.Cat
reproduceBbug foo_path ba_path =
    Api.request
        "POST"
        "/debug/stepPolarSession{foo}/{ba}"
        [ ( "foo",  foo_path ), ( "ba", String.fromInt ba_path ) ]
        []
        []
        Nothing
        Api.Data.catDecoder

[eriktim]

Yeah exactly. And how should it be converted to a string? As JSON blob, form-urlencoded, protobuf? As far as I know there's no logical answer to this. But please correct me if I'm wrong.

[timo-a]

I think the format can be reverse engineered from https://editor.swagger.io which can generate requests from user provided values. E.g.
foo: { "alpha" : 0 }
ba: 3
https://editor.swagger.io/debug/stepPolarSessionalpha,0/3

foo: { "alpha" : { "beta": 1 }, "theta": 2 }
ba: 3
https://editor.swagger.io/debug/stepPolarSessionalpha,[object Object],theta,2/3

Apparently there is an implementation for shallow json, but I doubt it is intentional.
Per a recent jar however the spec I provided is valid (or rather not recognized as invalid):

java -jar openapi-generator-cli-5.0.0-20201029.041527-838.jar validate -i /tmp/issue4.yaml
Validating spec (/tmp/issue4.yaml)
No validation issues detected.

So either

• it is not meant to be but the validator doesn't catch it yet or
• it is meant to be but swagger themselves haven't provided a reference implementation yet

Either way I'd say the ball is in their court.

Update: apparently object serialization as path parameter is a thing and serialization method can be specified in the spec:
https://swagger.io/docs/specification/describing-parameters/#path-parameters

[eriktim]

Interesting! That's a whole new topic to me. Seems pretty complex but feel free to create a PR if you want 😉