Union with null for optional fields

[davevanfleet]

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Problem

When optional fields in the prisma schema are null, the prisma client will explicitly return null from the model query methods. By decorating class properties with @IsOptional(), with the type as someField?: string (as opposed to someField?: string | null), we receive typescript errors such as type string | undefined is not assignable to type string | null.

Suggested solution

When a field in the schema has isRequired = false, append " | null" to the type generated for the class. The resulting generated class would then be defined this way:

export class SomeModel {
    @IsDefined()
    @IsInt()
    requiredField!: number;

    @IsOptional()
    @IsInt()
    optionalField?: number | null;

    @IsOptional()
    @IsString()
    anotherOptionalField?: string | null;
}

Alternatives

Additional context

I am trying to use this generator as a way of creating classes that can be used in NestJS controllers where an OpenAPI schema is generated. I would like to generate as much code as possible, and this generator seems to fit my needs in all ways except in how it handles creating the type definitions for optional fields.