Openapi-generator: [PHP] nullable attribute with value null gets removed

[githubERIK]

Description

_Given_ a nullable field in OpenAPI object

    SomeObject:
      type: object
      properties:
        someProperty:
          type: string
          nullable: true

_When_ HTTP Request has the object and it includes someProperty=null.

_Then_ the generated php client code does not include someProperty in the response.

openapi-generator version

master branch (version 3.3.4)
EDIT: also version 4.0.3

OpenAPI declaration file content or url

See the description

Command line used for generation

openapi-generator generate -g php

Steps to reproduce

Related issues/PRs

Suggest a fix/enhancement

Remove null-check if-block if ($value !== null) from https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/php/ObjectSerializer.mustache#L68

by changing this

if ($value !== null) {
    $values[$data::attributeMap()[$property]] = self::sanitizeForSerialization($value, $openAPIType, $formats[$property]);
}

to this

$values[$data::attributeMap()[$property]] = self::sanitizeForSerialization($value, $openAPIType, $formats[$property]);

[wing328]

@githubERIK thanks for reporting the issue and sharing the workaround.

But I think in certain use cases, the workaround may introduce additional null values in the payload, which are not present before.

I think we may need to maintain another associative array similar to openAPITypes to indicate if the property is nullable

[wing328]

I think we may need to maintain another associative array similar to openAPITypes to indicate if the property is nullable

@githubERIK does my comment earlier make sense to you?

[githubERIK]

The comment makes sense.

For nullables in model_generic.mustache,

protected static $openAPINullables = [
    {{#vars}}'{{name}}' => {{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{#hasMore}},
    {{/hasMore}}{{/vars}}
];

could be added and then accessed.

[githubERIK]

Things to keep in mind.

When a request goes out

• field is nullable and value is null
  
  
  
  • when somebody set the value to null on purpose then this should not be filtered out by ObjectSerializer
  
  
  • when somebody did not specify the value when using the constructor (causing the constructor to automatically set the value to null) then that null value should be filtered out
  
  

When a response comes in

• field is nullable and value is null
  
  
  
  • echo $response should show all null values.
  
  

[jorissteyn]

API platform supports partial PUT operations: omitting a field in the request does not clear the value on PUT operations. So I'm wondering, the change discussed here, how would the client distinguish nullable fields explicitly set to null versus fields omitted in the payload?

I believe this question is especially important because the client does not support PATCH requests.