[BUG] Nullable object reference produce invalid code in kotlin, php, java, typescript-fetch and probably more

[etremblay]

Description

To represent nullable object property, openapi recommend using a oneOf constuct. In version 3.0 in can be done with the nullable property, and in 3.1, with the null type.

3.0

propertyName:
          nullable: true
          oneOf:
            - $ref: '#/components/schemas/PropertyType'

3.1

        otherPropertyName:
          oneOf:
            - 'null'
            - $ref: '#/components/schemas/PropertyType'

In kotlin, the generatated type name is incorrect : OneOfLessThanPropertyTypeGreaterThan

@Json(name = "propertyName")
val propertyName: OneOfLessThanPropertyTypeGreaterThan? = null,

In php, the code is ok but the annotations produce an invalid class name : OneOfPropertyType|null

/**
     * Sets property_name
     *
     * @param OneOfPropertyType|null $property_name property_name
     *
     * @return self
     */
    public function setPropertyName($property_name)
    {
        $this->container['property_name'] = $property_name;

        return $this;
    }

In java the type is also wrong

public OneOfPropertyType getPropertyName() {
  return propertyName;
}

public void setPropertyName(OneOfPropertyType propertyName) {
  this.propertyName = propertyName;
}

In typescipt-fetch it produces a different result with 3.0 or 3.1 syntax

// 3.0

    /**
     * 
     * @type {PropertyType}
     * @memberof ModelWithNullableObjectProperty
     */
    propertyName?: PropertyType | null;

// 3.1
    /**
     * 
     * @type {Null | PropertyType}
     * @memberof ModelWithNullableObjectProperty
     */
    otherPropertyName?: Null | PropertyType | null;

openapi-generator version

master - 5.2.1

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: 'Title'
  version: latest
paths:
  '/':
    get:
      operationId: operation
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ModelWithNullableObjectProperty'
components:
  schemas:
    ModelWithNullableObjectProperty:
      properties:
        propertyName:
          nullable: true
          oneOf:
            - $ref: '#/components/schemas/PropertyType'
        otherPropertyName:
          oneOf:
            - 'null'
            - $ref: '#/components/schemas/PropertyType'
    PropertyType:
      properties:
        foo:
          type: string

Generation Details

docker run --rm -v ${PWD}:/local --user "${USER_ID}:${GROUP_ID}" openapitools/openapi-generator-cli:latest generate -i /local/model.yaml -g kotlin -o /local/kotlin
docker run --rm -v ${PWD}:/local --user "${USER_ID}:${GROUP_ID}" openapitools/openapi-generator-cli:latest generate -i /local/model.yaml -g php -o /local/php
docker run --rm -v ${PWD}:/local --user "${USER_ID}:${GROUP_ID}" openapitools/openapi-generator-cli:latest generate -i /local/model.yaml -g java -o /local/java
docker run --rm -v ${PWD}:/local --user "${USER_ID}:${GROUP_ID}" openapitools/openapi-generator-cli:latest generate -i /local/model.yaml -g typescript-fetch -o /local/typescript

Related issues/PRs

#2090

Suggest a fix

I went deep into the source code to understand how nullable types are handled.

ModelUtils.isNullable seems to have some logic to handle this but I'm unable to make an unit test pass in this code path.

I'm willing to contribute but may need some guidance.

[etremblay]

I think we can achieve something overriding

public String toOneOfName(List<String> names, ComposedSchema composedSchema) {
        Map<String, Object> exts = composedSchema.getExtensions();
        if (exts != null && exts.containsKey("x-one-of-name")) {
            return (String) exts.get("x-one-of-name");
        }
        return "oneOf<" + String.join(",", names) + ">";
    }

for some languages

[etremblay]

Apprently typescript does not like the 3.1 syntax either

/**
     * 
     * @type {Null | PropertyType}
     * @memberof ModelWithNullableObjectProperty
     */
    otherPropertyName?: Null | PropertyType | null;

[etremblay]

It's still in draft and the unit tests aren't completed yet, but I hava a working solutions for this issue.

#10602

I will try to complete a proper PR tomorrow

[charlie-harvey]

Just hit this issue. Is it still an issue? Did all the commits above get released?

Thanks.

[etremblay]

Just hit this issue. Is it still an issue? Did all the commits above get released?

Thanks.

I try to keep the pull request up to date but noboty ever merge it even if it's approved. I see that it's now conflicted, I'll fix it soon.

[wing328]

@etremblay our apologies. We're busy with too many PRs. I'll try to spend some time this week to next to go through it and let you know I've any feedback or question.

[etremblay]

@etremblay our apologies. We're busy with too many PRs. I'll try to spend some time this week to next to go through it and let you know I've any feedback or question.

Don't worry, I know you have a lot on your plate.

I updated the pull request with master and re-generated the samplesé