@hookform/lenses v0.7.0

React Hook Form Lenses

React Hook Form Lenses is a powerful TypeScript-first library that brings the elegance of functional lenses to React Hook Form. By providing type-safe manipulation of nested form state, it enables developers to precisely control and transform complex form data with ease. The library's composable lens operations make it simple to work with deeply nested structures while maintaining type safety, leading to more maintainable and reusable form components.

Installation

npm install @hookform/lenses

Quickstart

import { useForm } from 'react-hook-form';
import { Lens, useLens } from '@hookform/lenses';
import { useFieldArray } from '@hookform/lenses/rhf';

function FormComponent() {
  const { handleSubmit, control } = useForm<{
    firstName: string;
    lastName: string;
    children: {
      name: string;
      surname: string;
    }[];
  }>({});

  const lens = useLens({ control });

  return (
    <form onSubmit={handleSubmit(console.log)}>
      <PersonForm
        lens={lens.reflect(({ firstName, lastName }) => ({
          name: firstName,
          surname: lastName,
        }))}
      />
      <ChildForm lens={lens.focus('children')} />
      <input type="submit" />
    </form>
  );
}

function ChildForm({ lens }: { lens: Lens<{ name: string; surname: string }[]> }) {
  const { fields, append } = useFieldArray(lens.interop());

  return (
    <>
      <button type="button" onClick={() => append({ name: '', surname: '' })}>
        Add child
      </button>
      {lens.map(fields, (value, l) => (
        <PersonForm key={value.id} lens={l} />
      ))}
    </>
  );
}

function PersonForm({ lens }: { lens: Lens<{ name: string; surname: string }> }) {
  return (
    <div>
      <StringInput lens={lens.focus('name')} />
      <StringInput lens={lens.focus('surname')} />
    </div>
  );
}

function StringInput({ lens }: { lens: Lens<string> }) {
  return <input {...lens.interop((ctrl, name) => ctrl.register(name))} />;
}