How to propagate JsonSubTypes to Smallrye OpenAPI?

[LarsSven]

So I am a bit unsure whether this is a support request, bug report, or feature request. I have a REST DTO that looks as follows (in Kotlin):

/**
 * Defines a reference to a resource that should be retrieved as an input for the action.
 */
// Helps OpenAPI understand the different types of InputResourceReference
@Schema(
    description = "Defines a reference to a resource that should be retrieved as an input for the action.",
    oneOf = [InputResourceReference.Action::class, InputResourceReference.Assignment::class],
    discriminatorProperty = "type",
    discriminatorMapping = [
        DiscriminatorMapping(value = "action", schema = InputResourceReference.Action::class),
        DiscriminatorMapping(value = "assignment", schema = InputResourceReference.Assignment::class)
    ],
)
// Helps Jackson understand the different types of InputResourceReference
@JsonTypeInfo(
    use = JsonTypeInfo.Id.NAME,
    include = JsonTypeInfo.As.PROPERTY,
    property = "type"
)
@JsonSubTypes(
    JsonSubTypes.Type(value = InputResourceReference.Action::class, name = "action"),
    JsonSubTypes.Type(value = InputResourceReference.Assignment::class, name = "assignment")
)
sealed class InputResourceReference {
    /**
     * A reference of a resource generated and outputted by another earlier action within a profile.
     * E.g. The executable generated by the compile action as input for a testcase.
     *
     * @property stage The stage that contains the action that outputs the resource.
     * @property job The job that contains the action that outputs the resource.
     * @property action The action that outputs the resource.
     * @property uri The URI of the to-be-retrieved resource that is outputted by the action.
     */
    @NoArgConstructor
    data class Action(
        val stage: String,
        val job: String,
        val action: String,
        val uri: URI,
    ): InputResourceReference()

    /**
     * A reference to a resource that is available globally within an assignment.
     * These are for example files that should always be available within testcases, or the student submitted files.
     *
     * There are 2 available schemes for this resource URI:
     * - `file` for resources that are directly loaded from MinIO. Zips will be available in the container as a ZIP file.
     * - `zip` for resources that are loaded from MinIO and unzipped. The contents of the ZIP will be available in the container as individual files.
     *
     * @property uri The URI of the resource within MinIO.
     */
    @NoArgConstructor
    data class Assignment(
        val uri: URI,
    ): InputResourceReference()
}

This is basically an abstract class with 2 implementations. The way Jackson deals with this is that it adds a "type" property to the json serialization so that it knows which type it is. So a serialization would look like:

{
  "type": "action",
  "stage": "string",
  "job": "string",
  "action": "string",
  "uri": "https://example.com/"
}

OpenAPI however generates examples like:

[
  {
    "stage": "string",
    "job": "string",
    "action": "string",
    "uri": "https://example.com/"
  },
  {
    "uri": "https://example.com/"
  }
]

This doesn't add the type property, which I would really like to have added to the example, for the swagger UI.

I am not sure whether:

• This is supposed to work already and there is a bug
• This would be a feature that could be implemented such that Quarkus/SmallRye OpenAPI can deal with this automatically
• There is some thing I am missing on how to implement this in a nice way (preferably without having to add the type as an actual class property)

I was hoping that adding the "discriminatorProperty" and mapping would solve this issue.

Thanks in advance for any help, I really appreciate it.

[quarkus-bot[bot]]

/cc @EricWittmann (openapi), @Ladicek (smallrye), @MikeEdgar (openapi), @geoand (kotlin), @jmartisk (smallrye), @phillip-kruger (openapi,smallrye), @radcortez (smallrye)

[MikeEdgar]

@LarsSven you can try adding the property to the @Schema on InputResourceReference with @SchemaProperty and it will merge with the properties found on the sub-classes.

@Schema(
  // ... other @Schema attributes here
  properties = { @SchemaProperty(name = "type", implementation = String.class) }
)

[LarsSven]

That indeed works! Even the discriminatorMapping now works such that it adds the right type to the right object. Thanks!