Typing for Record, that can be a type or Record

[snow radish]

type FieldError = string;
type FieldErrors = {
    __errors?: FieldError[];
};

type FieldValidation = FieldErrors & {
    addError: (message: string) => void;
};

type FormValidation = Record<string, FieldValidation | Record<string, FieldValidation>>;

function isObject(value: Record<string, unknown> | undefined): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null && !Array.isArray(value);
}

async function recursive(root: Record<string, unknown>, current: Record<string, unknown>): Promise<FormValidation> {
    const formValidation: FormValidation = {};

    for (const [key, value] of Object.entries(current)) {
        if (isObject(current)) {
            formValidation[key] = await recursive(root, current);
        }
    }

    return formValidation;
}

In the example above , I have FormValidation is currently defined as

type FormValidation = Record<string, FieldValidation | Record<string, FieldValidation>>;

I think I need to somehow narrow the type or let tsc know whether I am dealing with a FiedValdiation or Record<string, FieldValidation on this line

formValidation[key] = await validate(formData, path, value);

The error I get here is

type 'FormValidation' is not assignable to type 'FieldValidation | Record<string, FieldValidation>'.
Type 'FormValidation' is not assignable to type 'FieldValidation'.
Property 'addError' is missing in type 'FormValidation' but required in type '{ addError: (message: string) => void; }'.ts(2322)
index.d.ts(108, 5): 'addError' is declared here.

[vivid stump]

would that even be correct though

btw you don't have an await validate(formData, path, value); line in your playground

[snow radish]

FormValidation is definitely wrong but I'm not sure how to type it to be FieldValidation or a similar record

[snow radish]

or is this assertion ok

formValidation[key] = await validate(formData, path, value) as Record<string, FieldValidation>;

[vivid stump]

well

there's only one way to find out

[snow radish]

it compiles but I wish there was a way without the assertion

[vivid stump]

well, the assertion should be required - because you aren't actually checking that addError is there, so you can't be sure it's actually a FieldValidation

[nova sorrel]

judging this statement let tsc know whether I am dealing with a FiedValdiation or Record<string, FieldValidation on this line

can you not say this ? ```ts
type FieldValidation = Record<string, FieldValidation> | FieldValidation;

sorry if it's not correct, still learning here 😛

[vivid stump]

that's not the issue, the issue is that they have a value that typescript doesn't know is a FieldValidation

but also that type would be incorrect, yes, FieldValidation cannot be | itself

[nova sorrel]

Ah okay, thanks for clarifying

[snow radish]

I settled on this

export type FormValidation = {
  [name: string]: FieldValidation | FormValidation;
};

[vivid stump]

!close