Redocly lint error for nullable object properties

[drewish]

Is there an existing issue for this?

• I have searched the existing issues

#2948 seems similar but was closed as fixed and I'm presuming it was incorporated into the 8.x branch.

Current behavior

With the plugin enabled and looking at the Typescript code a property like:

  @ApiProperty({
    description: 'The user that owns the cat',
  })
  nullableOwner: UserDto | null;

, it generates the schema's property like:

          "nullableOwner": {
            "nullable": true,
            "description": "The user that owns the cat",
            "allOf": [
              {
                "$ref": "#/components/schemas/UserDto"
              }
            ]
          }

Redocly's linter flags as an error:

[4] dist/api-spec.json:84:25 at #/components/schemas/CreateCatDto/properties/nullableOwner/nullable

The `type` field must be defined when the `nullable` field is used.

82 | },
83 | "nullableOwner": {
84 |   "nullable": true,
85 |   "description": "The user that owns the cat",
86 |   "allOf": [

Error was generated by the struct rule.

Minimum reproduction code

https://github.com/drewish/swagger-nullable-poc

Steps to reproduce

Setup the repro repo:

git clone https://github.com/drewish/swagger-nullable-poc
cd swagger-nullable-poc
npm i

Start it up to generate the swagger file (main.ts is saving a copy)

npm start

Then use redocly to lint the file:

npx @redocly/cli@latest lint dist/api-spec.json

There are unrelated errors I didn't bother cleaning up. The relevant one is:

The `type` field must be defined when the `nullable` field is used.

Expected behavior

One workaround I've see for this (microsoft/typespec#4584) was to just add type: 'object' as a sibling:

          "nullableOwner": {
            "type": "object",
            "nullable": true,
            "description": "The user that owns the cat",
            "allOf": [
              {
                "$ref": "#/components/schemas/UserDto"
              }
            ]
          }

That renders nicely in Redocly's UI:

And looks the same in SwaggerUI:

It seems like in ModelClassVisitor.createTypePropertyAssignments(), when we create the nullable property:

swagger/lib/plugin/visitors/model-class.visitor.ts

Lines 437 to 443 in 8cb1ee8

	return [
	...propertyAssignments,
	factory.createPropertyAssignment(
	'nullable',
	createBooleanLiteral(factory, true)
	)
	];

We could also add type: 'object'.

But, we'd also need a change in SchemaObjectFactory.extractPropertiesFromType() to keep it from deleting the type:

swagger/lib/services/schema-object-factory.ts

Line 214 in 8cb1ee8

delete schemaObjectMetadata.type;

Package version

11.0.3

NestJS version

11.0.1

Node.js version

v20.16.0

In which operating systems have you tested?

• macOS
• Windows
• Linux

Other

No response

[drewish]

I'm going to try out a PR for this. If nothing else we can run a patch/fork.

[merldienACN]

We also encounter this issue with enums. It seems to be related to the fix deployed for this issue: #1889

Using the "AllOf" field is new to NestJS API generation, if you manually adapt the generated Api-Spec to remove AllOf, redocly can lint again