[BUG][kotlin] Make Kotlin client generate comma separated list for array path params

[sjoblomj]

resolve #7199

The Kotlin client codegen currently cannot handle path params of type array. The code being generated for the path is currently this: path = "/stuff/{ids}".replace("{"+"ids"+"}", "$ids"). This works fine, but not if ids is a list or an array, since the toString() method is used to create the string.

With the current code, if ids contains 123 and 456, then path would be set to:

• /stuff/[123,456] if collectionType is list.
• /stuff/[Ljava.lang.String;@6a98f353 if collectionType is array.

In both cases, /stuff/123,456 is the expected result.

If we change the code from
path = "/stuff/{ids}".replace("{"+"ids"+"}", "$ids")
to
path = "/stuff/{ids}".replace("{"+"ids"+"}", ids.joinToString(",")),
we get the expected result.

OpenAPI Spec demonstrating this:

openapi: 3.0.0
info:
  version: 1.0.0
  title: Demo
paths:
  '/{ids}':
    get:
      parameters:
        - name: ids
          in: path
          required: true
          schema:
            type: array
            items:
              type: string
          style: simple
      responses:
        200:
          description: Successful operation

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• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
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  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
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@jimschubert @dr4ke616 @karismann @Zomzog @andrewemery @4brunu @yutaka0m

[4brunu]

Hi, could you please run the following commands and commit the changes, please? Thanks

./mvnw clean package 
./bin/generate-samples.sh
./bin/utils/export_docs_generators.sh

[sjoblomj]

Hi, could you please run the following commands and commit the changes, please? Thanks

./mvnw clean package 
./bin/generate-samples.sh
./bin/utils/export_docs_generators.sh

Done, although I see no changes except for the scripts butchering a lot of files by turning paths and file endings into Windows style, and performing some formatting.

[4brunu]

Sorry the script did end up creating a lot of noise not related to this command.
Could you please revert the last commit and commit the changes created by this command?

./bin/generate-samples.sh bin/configs/kotlin*

[sjoblomj]

Sorry the script did end up creating a lot of noise not related to this command. Could you please revert the last commit and commit the changes created by this command?

./bin/generate-samples.sh bin/configs/kotlin*

Reverted and forced pushed the output from the command.

Again, there are no changes except for the script re-indenting some lines, and it looks to me like the changes are for the worse. Should I revert this change too, or do we want it? :)

[4brunu]

Can you revert it please?
Looks like the API spec doesn't have a test case for this.
Did you tested this locally?

[sjoblomj]

Can you revert it please? Looks like the API spec doesn't have a test case for this. Did you tested this locally?

Reverted. I tested it locally.

I wanted to add a test case, but did not see where or how to test it. If you could give me some pointers to how it would be tested, I could try to add one.

[4brunu]

The easiest way would be to create a spec file and a new sample project

[4brunu]

Or you could create a new spec file based on another one that already exists, and update one of the kotlin sample projects to use it, this would be much easier

[sjoblomj]

Or you could create a new spec file based on another one that already exists, and update one of the kotlin sample projects to use it, this would be much easier

Just to be clear, when you say one of the kotlin sample projects, which file(s) do you refer to?

[4brunu]

The sample projects have a configuration file, for example this one.
https://github.com/OpenAPITools/openapi-generator/blob/master/bin/configs/kotlin-gson.yaml
In that directory you will find other yaml files for the different kotlin sample projects.
In the configuration file, you will find the inputSpec, the outputDir, the additionalProperties, etc.
You can create a new configuration file and a new input spec to create a new sample project.

[wing328]

Tested with the provided spec and the result is good:

Starting a Gradle Daemon (subsequent builds will be faster)

> Task :compileKotlin
w: /private/tmp/kotlin-client/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt: (121, 6): This class can only be used with the compiler argument '-Xopt-in=kotlin.RequiresOptIn'

BUILD SUCCESSFUL in 42s
3 actionable tasks: 3 executed

The output looks correct:

        return RequestConfig(
            method = RequestMethod.GET,
            path = "/{ids}".replace("{"+"ids"+"}", ids.joinToString(",")),
            query = localVariableQuery,
            headers = localVariableHeaders,
            body = localVariableBody
        )

[wing328]

I'll add a CI test after merging this PR