[REQ][typescript-*] String Enums

[eseliger]

Is your feature request related to a problem? Please describe.

Since TS version 2.4 string enums are supported, which are the preferred way of defining enums that can have string values (over the legacy object-type-dualism). https://www.typescriptlang.org/docs/handbook/enums.html#string-enums

Describe the solution you'd like

I implemented it already on a branch for internal use at my company, which is using an additional property called "stringEnums" for now. No breaking change since it needs to be enabled, off by default

Describe alternatives you've considered

Other solutions that would be possible are:

• Default to string enums, which would be incompatible with TS<2.4 and be a breaking change
• Add a proprietary flag to the openapi spec. I think this is not really desirable because most problems that are solved this way are rather specific to the operation, whereas this is more of a global flag IMO.

Comparison of outputs

before:

export interface User {
    title: User.TitleEnum
    name: string
}
export namespace User {
	export type TitleEnum = 'Mr' | 'Mrs' | 'Ms'
	export const TitleEnum = {
	    Mr: 'Mr' as Title,
	    Mrs: 'Mrs' as Title,
	    Ms: 'Ms' as Title,
	}
}

with string enums enabled:

export interface User {
    title: UserTitle
    name: string
}
export enum UserTitle {
    Mr = 'Mr',
    Mrs = 'Mrs',
    Ms = 'Ms',
}

[macjohnny]

@eseliger a contribution would be welcome!

[eseliger]

@macjohnny I just realized when I wanted to port the changes to the other typescript clients, that most of them use string enums already, but typescript-angular doesn't.

What would you prefer?

• Align it and make it a breaking change
• Only implement it with the flag for typescript-angular and might remove it in v5

this one I meant 🤦‍♂

[macjohnny]

I would prefer to go with the flag, and decide later whether to default to true and introduce a breaking change. The typescript-generators are subject to refactoring, see #802

[bodograumann]

This is not implemented for typescript-inversify.

Out of interest: What is your use case of enums in contrast to union types? I have found that the latter are sufficient.

[macjohnny]

Enum values can be re-used elsewhere

[ffMathy]

An exported type can also be used anywhere, no?

[Morriz]

this would be nice to see...has there been any activity on this request?

[bodograumann]

Which generator are you using, @Morriz ?

[Morriz]

Thanks for asking! Just upgraded express-openapi from 8.0.0 to 9.0.3 and that solved it ;)

[Morriz]

Grrr. Too quick. The typescript that gets generated is fine, but the dist/*js are not using the strings.

[bodograumann]

Could you please create a new issue, @Morriz ?

[Morriz]

not needed...the stuff shown in the debugger is not what is used I deduce. TS that generates enum NOT using strings is shown, but the JS is using strings.