Type inference does not work correctly after 1.2.3

[jashworth]

Describe the bug

With 1.2.3, type inference works as expected (via DeepKeys).
With 1.2.4, and up, type inference doesn't appear to be working correctly.

Your minimal, reproducible example

https://codesandbox.io/p/devbox/tender-elbakyan-pdsmh4?file=%2Fsrc%2FScheduleForm.tsx%3A74%2C43

Steps to reproduce

1. At ScheduleForm.tsx:81, observe that full Intellisense is provided for values of the name prop.
2. Update the @tanstack/react-form version to 1.2.4 or above.
3. At ScheduleForm.tsx:81, observe that full Intellisense is no longer provided.

Expected behavior

I expected version 1.2.4 to behave in a similar way to 1.2.3

How often does this bug happen?

Every time

Screenshots or Videos

No response

Platform

• Windows 10
• Chrome 135.x

TanStack Form adapter

react-form

TanStack Form version

1.2.4

TypeScript version

5.7.2

Additional context

No response

[Balastrong]

There might be something wrong with CodeSandbox, if I just click the link it opens up with a few errors already on the imports which doesn't seem related to the issue.

---

With that said, thanks for the report. I think the types are breaking on discriminated unions.

A minimal example:

type FormData = { name: string } & ({ variant: "foo" } | { variant: "bar"; baz: string });

[Balastrong]

Can you please try to install this version and check if the issue is fixed for you?

npm i https://pkg.pr.new/@tanstack/react-form@1393

[pulsedemon]

@Balastrong I tested your pr and it didn't fix my issue. See https://codesandbox.io/p/devbox/affectionate-bardeen-p975cm src/fields/NameField.tsx

[cmanou]

@Balastrong Also confirming that this is occurring for me and #1393 did not fix it either

[Balastrong]

I tested your pr and it didn't fix my issue. See https://codesandbox.io/p/devbox/affectionate-bardeen-p975cm src/fields/NameField.tsx

That's not how useFormContext & the composition API works. Please check the doc and the example.

You should use useFieldContext when you define a field component, then follow the other steps in the docs/example to connect all the steps.

---

Also confirming that this is occurring for me and #1393 did not fix it either

Can you please provide an example or more details? "Doesn't work for me" unfortunately doesn't help anyone.

[jashworth]

https://pkg.pr.new/@tanstack/react-form@1393

This seems to fix the issue.

Many thanks

[Balastrong]

Thanks! This is now available in v1.3.1

[luski]

I still have this issue with v1.3.1

[Balastrong]

I still have this issue with v1.3.1

Can you please share an example to reproduce the issue? The original one is fixed, in case we missed an edge case please let us know.

[luski]

I still have this issue with v1.3.1

Can you please share an example to reproduce the issue? The original one is fixed, in case we missed an edge case please let us know.

Of course, here's a short snippet. Is it sufficient in that form, or should I prepare a codesandbox project?

import { useForm } from "@tanstack/react-form";

export type MyType = { type: "a" } | { type: "b" };

function useMyType(): { myType: MyType } {
  return {
    myType: {
      type: "a",
    },
  };
}

export function MyForm() {
  const { myType } = useMyType();

  const form = useForm({
    defaultValues: {
      name: "",
      myType,
    },
  });

  return (
    <form
      onSubmit={(e) => {
        e.preventDefault();
        e.stopPropagation();
        form.handleSubmit();
      }}
    >
      <form.Field name="name">
        {(field) => (
          <input
            type="text"
            value={field.state.value}
            // here's the typescript error: string is not assignable to type 'never'
            onChange={(e) => field.handleChange(e.target.value)}
          />
        )}
      </form.Field>
    </form>
  );
}

[Balastrong]

Thanks! Keys are now properly inferred but there's still something not working on values

[Balastrong]

Can you try again with v1.3.2?

[cmanou]

@Balastrong still broken for me here is my reproduction the actually issue seems to be my type of my content field if I remove the content field then my actual filters field starts playing nice otherwise it just becomes any.

https://www.typescriptlang.org/play/?strictFunctionTypes=false&strictPropertyInitialization=false&strictBindCallApply=false&noImplicitThis=false&noImplicitReturns=false&alwaysStrict=false&declaration=false&target=9&isolatedModules=true&verbatimModuleSyntax=true#code/JYWwDg9gTgLgBAbznGBPMBTOAlDBDAYxgDFoQBRADxgwDsATDegQTGDgF84AzKCEOACIAAjDy0AzmIIBrAPRR8RALTcyggNxw5clOgwSAXHACMAOgDMZgEwAoUJFh7MiOACkAygHkAcgGEIWhogzh4+AQByUWAwMTAFJRgIjVt7cGh4ACo4PAkcRLD+IUVCGE1UjEpHeDQXcnpgGFxS0igBAF58lrIqYMYWNgAeW2QEEeQeYAAbGigjOAAKcYm4AB9EZZWJ2oxjQUUAc2BA8q2tgDc8KYBXA2MpKGBaA4BtAF0Us+QOTeR1sa+230ewkGAOIDoZU+gLglxudzgDyerw+vwmPzO-zRKx2eye9GuD1QpxhcNu9xgj2e0LOGImAEp3jTtLoAiAISEpk8sAAjDBTCAAd0mlAMcEamwIgWCMGMnl8ASCkOZOjgUqVQWM11oMloQto0I4ABpxuJUCbkGaLTlaObTbbrVb7XbLQ7nY7bbYAHwpWyVapqwJSOB+NrEaazCQea481odRZINRtTjGRNkYz1RrNIhxzj0uDtL0bZCKGDXKC0RabQZetGDJMgMzh-n0bFqgAW03oilo7QQC24wBb+cLkxbZikeBoZjJGDMIDwYAWCzwI6LgzAXoQeDMOw4gzkm-pdLOIAgjHagjwUCgeGJbdoeAhl8HMwwc0EaLktbO9bITaHKZW0BAhOyAns+wHQD6DXdxvB8CdKWRYBuFQKDx0nadZ2PB8nwwS91RlT8zm-atSOQekUh+IA

Note: I only set that content field as a full blob so don't really need the deep access on it but I still want it to be typed potentially there is a better way to describe it

[Balastrong]

Thanks!

Looks like the value type inference now breaks if there's an explicit any somewhere, making all types as any-

You can see that even with this, if you comment or give a proper type to foo it works.

type FormData = {
  name: string;
  foo: any;
}

[Balastrong]

Handling of any is fixed in v1.4.1 🚀

I'll try to close this issue again but please if you spot some more types that aren't inferred right, let us know! Thank you everyone!