[BUG] [php] [php-nextgen] Return type hint does not consider HTTP 204

[imba28]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

When you have a path that either returns a 204 response (without any body) or any other response code with a body, a type error is thrown due to the return type hint not being nullable.

openapi-generator version

7.13.0

OpenAPI declaration file content or url

openapi: 3.0.0
paths:
  "/pet":
    delete:
      responses:
        "204":
          description: Pet deleted
        "404":
          description: Pet not found
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: string

Generation Details

docker run --rm -v "${PWD}:/local" openapitools/openapi-generator-cli:v7.13.0 generate \
    -i https://gist.githubusercontent.com/imba28/cc57b1589b084a689958869fc5b3a34f/raw/90aacb27985765c35daf3118c2720859756b74a6/spec.yaml \
    -g php-nextgen \
    -o /local/out/php

Steps to reproduce

use OpenAPI\Client\Api\DefaultApi;
use OpenAPI\Client\Configuration;

require 'vendor/autoload.php';

$config = new Configuration();
$config->setHost('https://httpstat.us/204');

$api = new DefaultApi(config: $config);

$api->petDelete();

Expected output

I would expect the script to finish without any errors since the API spec is valid.

Actual output

Fatal error: Uncaught TypeError: OpenAPI\Client\Api\DefaultApi::petDelete(): Return value must be of type OpenAPI\Client\Model\PetDelete404Response, null returned in /var/www/html/src/Api/DefaultApi.php:142
Stack trace:
#0 /var/www/html/test.php(13): OpenAPI\Client\Api\DefaultApi->petDelete()
#1 {main}
  thrown in /var/www/html/src/Api/DefaultApi.php on line 142

The cause of the type error seems to lie within the petDeleteWithHttpInfo method. The first element of its return value is null when dealing with 204 responses. The type hint of petDelete doesn't reflect that yet.

public function petDelete(
        string $contentType = self::contentTypes['petDelete'][0]
 ): \OpenAPI\Client\Model\PetDelete404Response
 {
        list($response) = $this->petDeleteWithHttpInfo($contentType);
        return $response;
 }

public function petDeleteWithHttpInfo(
        string $contentType = self::contentTypes['petDelete'][0]
    ): array
    {
        $request = $this->petDeleteRequest($contentType);

        try {
            // code omitted...
            return [null, $statusCode, $response->getHeaders()]; // HTTP 204 => body is null
        } catch (ApiException $e) {
            switch ($e->getCode()) {
                case 404:
                    $data = ObjectSerializer::deserialize(
                        $e->getResponseBody(),
                        'OpenAPI\Client\Model\PetDelete404Response',
                        $e->getResponseHeaders()
                    );
                    $e->setResponseObject($data);
                    throw $e;
            }
        
            throw $e;
        }
    }

Related issues/PRs

• [PHP][php-nextgen] List all possible return types (fix #17113) #20335

Suggest a fix

HTTP 204 responses seem to be an edge case which https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpNextgenClientCodegen.java#L193 doesn't handle yet.

Maybe the code generator could include null as a return type if response.dataType != null || operation.responses.size() > 1 . Furthermore, it might be sufficient to only consider a subset of the responses since any non-2xx status code triggers an exception.

[stevenbrookes]

I've just been hit by the same issue. I managed to work around it by modifying the openapi spec to says

    '204':
      description: No content
      content:
        application/json:
          schema:
            type: string