Nullable Enum not generated as nullable

[jbdemonte]

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

Using the following annotation:

export class ClientResponseDto {
  @Expose()
  @ApiProperty({ enum: PaymentTermsEnum, enumName: 'PaymentTermsEnum', nullable: true })
  paymentTerms!: PaymentTermsEnum | null;

}

openapi-generator 5.4 generates:

export interface GetClientByIdResponseDto { 
    paymentTerms: PaymentTermsEnum;

I need to use the following workaround to get it nullable:

export class ClientResponseDto {
  @Expose()
  @ApiProperty({ oneOf: [{ type: 'enum', $ref: 'PaymentTermsEnum', nullable: true }] })
  paymentTerms!: PaymentTermsEnum | null;
}

=>

export interface GetClientByIdResponseDto {
    paymentTerms: PaymentTermsEnum | null;
}

Minimum reproduction code

https://github.com/jbdemonte/issue-nestjs-openapi-generator-nullable-enum

Steps to reproduce

1. npm install
2. npm run generate:angular-client

Expected behavior

the exported value type should be value!: FooBarEnum | null;

Package version

5.2.1

NestJS version

8.4.4

Node.js version

16.13.1

In which operating systems have you tested?

• macOS
• Windows
• Linux

Other

No response

[kamilmysliwiec]

Let's track this here #2051

[milo526]

Can we re-open this issue?

The problem is still present in the latest version of this library, and the linked merge request is closed.

[kamilmysliwiec]

This should be fixed in newer versions of the library. Could you create a separate issue and provide a minimum reproduction repository?

[mothershipper]

We're also experiencing this issue on the latest version of the library.

The problem is that when you name the enum, Nest is extracting the enum into a shared type (with$ref), but leaving the nullable: true on the property rather than the shared type:

objects:
  Enum:
    type: string
    values:
      - One
      - Two
  MyApiObj:
    properties:
       someField:
         $ref: objects/Enum
         nullable: true

OpenAPI treats $ref as a replace operation rather than merge, so nullable: true is lost.

If you don't supply a name to the ApiProperty decorator, Nest doesn't extract the enum definition into a separate type, declaring it inline so nullable: true is preserved. While this works, it also means code-generators generate worse names for the enum.

It looks like Nest added support for the nest compiler to generate unnamed nullable enum types as described above, but not named types. Though, if the named enum is used in difference contexts (one nullable, one not) you really can't extract to a shared named type, unless using OpenAPI 3.1.x semantics for nullable properties, i.e.

objects:
  Enum:
    type: string
    values:
      - One
      - Two
  MyApiObj:
    properties:
       someField:
         oneOf:
           - $ref: objects/Enum
           - type: 'null'

[jsangilve]

Spent today more than one hour dealing with the issue perfectly described by @mothershipper 🔝 : when the enumName property is used, it does not work as expected and the nullable: true is ignored in the generated TS.

[jessecoleman]

Would be nice to get a fix for this, I also just ran into the same behavior.

[wrheinheimer]

This seems to be fixed by adding the following lines to SchemaObjectFactory.createEnumSchemaType:

const wrappedRef = metadata.nullable ? { allOf: [{ $ref }] } : { $ref };
const refHost = metadata.isArray ? { items: wrappedRef } : wrappedRef;

[MrCode1997]

Hi, i still have the issue, could you fix it?
At the moment this problem is blocking our pipelines

[BenStirrup]

Any update ?

[kamilmysliwiec]

It should be fixed in the latest version. If you run into any issues, please create a new issue with a reproduction repository