When using the @Groups decorator in models - how can I make the TS type correct for each group?

[markusenglund]

Hey!

Let's say I have a model that looks like this:

export class Example {
    @Required()
    @RequiredGroups('!action.create')
    id?: string;

    @Required()
    content: string;

    constructor(options: any) {
        this.content = options.content;
        this.id = options.id
    }
}

The id property is not required when using the action.create group, but is required in all other cases. I want the code-base to be correctly typed, and not have models incorrectly typed as having the id property during create when it won't be there at runtime. Is there a convenient way to generate two separate TS types for the two cases? Ideally without creating a separate class for each group? I tried to do the following:

export class Example<T extends 'create' | 'get'> {
    @Required()
    @RequiredGroups('!action.create')
    id: T extends 'create' ? undefined : string;

    @Required()
    content: string;

    constructor(options: any) {
        this.content = options.content;
        this.platform = options.platform;
    }
}

However, the generated OpenAPI spec now says id has "type": "object".

Any ideas for good solution?

[Romakita]

Hello @markusenglund

When you use a complex interface like "T extends 'create' ? undefined : string;" , typescript doesn't set String as metadata but Object.

This is why Ts.ED isn't able to infer the correct type and this is why Ts.ED provide @Property decorator ;). The correct code is:

export class Example<T extends 'create' | 'get'> {
    @Property(String)
    @Required()
    @RequiredGroups('!action.create')
    id: T extends 'create' ? undefined : string;

    @Required()
    content: string;

    constructor(options: any) {
        this.content = options.content;
        this.platform = options.platform;
    }
}

See you
Romain