Type instantiation is excessively deep and possibly infinite with recursive field value structure
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Description
Describe the bug
We are trying to adopt tanstack form in our CMS, where we have complex and recursive content structure, and in the form types we represent the field values as:
export type FieldValues = {
[key: string]: string | string[] | number | boolean | null | FieldValues | FieldValues[];
};
Also, we are passing down the form instance via a provider as our codebase is huge and we need a context to share the form instance deep down the tree.
type FormContextType = ReactFormExtendedApi<
FieldValues,
FormValidateOrFn<FieldValues> | undefined,
ZodType<FieldValues, ZodTypeDef, FieldValues>,
FormAsyncValidateOrFn<FieldValues> | undefined,
FormValidateOrFn<FieldValues> | undefined,
FormAsyncValidateOrFn<FieldValues> | undefined,
FormValidateOrFn<FieldValues> | undefined,
FormAsyncValidateOrFn<FieldValues> | undefined,
FormAsyncValidateOrFn<FieldValues> | undefined,
{}
> | null;
export const FormContext = React.createContext<FormContextType>(null);
export const FormProvider = ({
children,
value,
}: {
children: React.ReactNode;
value: FormContextType;
}) => {
return <FormContext.Provider value={value}>{children}</FormContext.Provider>;
};
function App() {
const form = useForm({
defaultValues: defaultPeople,
onSubmit({ value }) {
alert(JSON.stringify(value));
},
});
return (
<FormProvider value={form}>
<form
onSubmit={(e) => {
e.preventDefault();
e.stopPropagation();
form.handleSubmit();
}}
></form>
</FormProvider>
);
}
But we are running into TS issue - "Type instantiation is excessively deep and possibly infinite" when trying to do this. I believe these kind of recursive field types are common and it should not cause issues. Maybe I am doing something wrong here? The issue is on this line
return (
<FormProvider value={form}>
Your minimal, reproducible example
https://stackblitz.com/edit/tanstack-form-bsyh9m5c?file=src%2Findex.tsx
Steps to reproduce
See the reproduction here
https://stackblitz.com/edit/tanstack-form-bsyh9m5c?file=src%2Findex.tsx
Expected behavior
The type error should not be there
How often does this bug happen?
Every time
Screenshots or Videos
No response
Platform
N/A
TanStack Form adapter
react-form
TanStack Form version
1.9.1
TypeScript version
No response
Additional context
No response
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the StackBlitz reproduction in src/index.tsx and reproduce the error at the FormProvider value={form} line. Inspect how the recursive FieldValues type interacts with ReactFormExtendedApi and the useForm result; done means the reproduction type-checks without the excessively-deep instantiation error.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- react, typescript
- Domain
- frontend
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100