Property 'getFieldset' does not exist on type 'FieldMetadata'

[binajmen]

Describe the bug and the expected behavior

I have a simple form:

  const [form, fields] = useForm({
    lastResult,
    defaultValue: user,
    shouldValidate: "onBlur",
    onValidate({ formData }) {
      return parseWithZod(formData, { schema: dataSchema });
    },
  });
  const profile = fields.profile.getFieldset();

The LSP and lint does not report an error. However, typecheck is:

error TS2339: Property 'getFieldset' does not exist on type 'FieldMetadata<JsonifyObject<{ createdAt: Date; userId: string; ... }> | null, JsonifyObject<...>, string[]>'.

Conform version

1.0.2

Steps to Reproduce the Bug or Issue

Run typecheck while using getFieldset

What browsers are you seeing the problem on?

No response

Screenshots or Videos

No response

Additional context

No response

[edmundhung]

Can you please share your zod schema?

[aaronadamsCA]

I'm seeing the same issue upgrading from v1.0.0 to v1.0.2.

Here's a short repro: TypeScript playground

import { useField } from "@conform-to/react";

interface Schema {
  foo: string;
}

() => {
  const [{ getFieldset }] = useField<Schema>("name");
//         ^ Property 'getFieldset' does not exist on type 'FieldMetadata<Schema, Record<string, unknown>, string[]>'.
  const { foo } = getFieldset();
};

// Workaround
() => {
  const [{ getFieldset }] = useField<{ foo: string }>("name");
  const { foo } = getFieldset();
};

The problem is that an interface without an index signature never extends Record<string, unknown>. I suspect the correct check may be extends object.

(Edit: I see this change alone wouldn't solve OP's problem, since that schema is nullable. I don't understand why an entire schema would ever be null or undefined, but given Conform already uses Exclude<Schema, undefined> to remove undefined, you could just switch this to NonNullable<Schema> to additionally remove null and solve OP's problem at the same time. Again, though, I don't understand why that's there in the first place, or if this could have further effects.)

[edmundhung]

The problem is that an interface without an index signature never extends Record<string, unknown>.

I have never thought about this 🤔 Interesting.

I suspect the correct check may be extends object.

Feel free to submit a PR if you have any ideas. I did some changes to improve the type inference on #459 recently but I am also uncertain if I covered all possible cases.

I don't understand why an entire schema would ever be null or undefined

I think part of the issue is the same as #478 in which TS infers the schema based on the default value instead. But your solution looks good to me.

[aaronadamsCA]

@edmundhung, I've filed #508 with the solution I described, plus updated tests.

[edmundhung]

Thank you @aaronadamsCA! I am busy with something else right now but I wish to come back to it later this week and will likely cut a release with a few other fixes. :)

[binajmen]

Apologies for the delayed response. I've observed that the issue arises when a default value is supplied in an incorrect format. However, it's unclear why this impacts getFieldSet. Since this seems to be a user-related issue, I don't believe further investigation is necessary.