README

About

Integration and utility library for react-hook-form (and zod). Declaratively configure your forms via global and form-level options.

Features

• TypeScript-first
• global configuration (RhfUtilsClientConfig)
  • RHF (UseFormProps) and utilities (RhfUtilsFormOptions) options defaults
  • inject your own hooks and UI (FormChildrenWrapper)
  • server error transformation (onSubmitErrorUnknown)
  • RHF FormState.errors logging/throwing (RhfUtilsClientConfig.fieldErrors)
• form-level configuration (RhfUtilsZodForm)
  • RHF and utilities options overrides
    • extendable utilities options type (RhfUtilsFormOptions)
  • throw error (FormSubmitError) in submit handler to add errors to RHF context and fail submit
  • handle submit error (onSubmitError)
  • dependency injection for children (RhfUtilsZodForm.Children), including:
    • formId, formRef, RHF context, utilities options
    • schema-typed Controller component and FormSubmitError class
• simpler/flatter FieldErrors structure (FlatFieldErrors)
  • context groups errors into all, fields, roots, and orphans (useFlatFieldErrorsContext)
• safer FieldValues type (SafeFieldValues)
• zod support, including input/output types for transformations
• ~3.2kB min+gzip core (excluding peer dependencies)

Install

npm install @paragrav/rhf-utils  # npm
pnpm install @paragrav/rhf-utils # pnpm
yarn add @paragrav/rhf-utils     # yarn

Quick Start

• 🔗 Config (RhfUtilsClientConfig): define your global config (optional)
• 🔗 Provider (RhfUtilsClientForZodContextProvider): add to your global stack
• 🔗 Form (RhfUtilsZodForm): use as form component

Config

Create a config (RhfUtilsClientConfig) object with desired global config and default options. Config applies across all forms, and defaults can be overridden per form.

export const rhfUtilsClientConfig: RhfUtilsClientConfig = {
  // overridable at individual form level
  defaults: {
    // globally-relevant subset of RHF's `UseFormProps` options
    rhf: {
      mode: 'onSubmit',
    },

    // RhfUtilsFormOptions (see further below)
    utils: {
      stopSubmitPropagation: true,
      devTool: import.meta.env.DEV && { placement: 'top-right' },
    },

    // global default native form props
    form: {
      noValidate: true,
      className: 'my-form-class',
    },
  },

  // optional form component (defaults to primitive HTML form)
  FormComponent: Form.Root,

  // optional wrapper component to inject your own hooks and components
  // around all RhfUtilsZodForm instances
  FormChildrenWrapper: (
    // UseRhfUtilsFormChildrenProps
    {
      formId, //          unique id string
      formRef, //         ref
      context, //         rhf UseFormReturn (without proxy `formState`)
      options, //         RhfUtilsFormOptions (with any custom props)
      Controller, //      rhf controller (SafeFieldValues-typed; no schema at this level)
      FormSubmitError, // error class (SafeFieldValues-typed; no schema at this level)
      children, //        RhfUtilsZodForm's Children instance
    },
  ) => {
    useMyGlobalFormHook();

    // form-level control of your own hooks/behaviors via custom option props
    // (see "Extend RhfUtilsFormOptions" section for more info)
    useMyOptionalFormHook({
      enabled: !!options.enableMyOptionalFormHook,
    });

    return (
      <>
        {/* RhfUtilsZodForm.Children "outlet" (see "Component Hierarchy" section) */}
        {children}

        {/* root errors list */}
        <RootErrorsList />
      </>
    );
  },

  // hook that returns callback to determine whether form can be cancelled
  // if `true`, `RhfUtilsZodForm.onCancel` at form-level is called (e.g., parent component hides form)
  // this allows you to handle non-navigational blocking/prompting
  useCanFormBeCancelled: () => {
    const { isDirty } = useFormState();
    const asyncPrompt = useAsyncPrompter();

    // return callback to be called at event-time
    // with same props as `RhfUtilsClientConfig.FormChildrenWrapper`
    return async (props: RhfUtilsFormChildrenWrapperProps) =>
      !isDirty || // rhf form state not dirty
      (await asyncPrompt('Are you sure you want to cancel?')); // or user confirms
  },

  // non-FormSubmitError thrown in onSubmit
  // use case: handle and transform server error data for frontend
  onSubmitErrorUnknown: (
    error, // unknown
  ) => {
    // return FormSubmitFieldErrors object to be merged to RHF context errors
    if (isMyServerError(error))
      return transformMyServerErrorToFormSubmitFieldErrors(error);
  },

  // RHF FormState.errors output for debugging
  fieldErrors: {
    // callbacks to determine when to output information about field errors
    // provided `FlatFieldErrorsContext` (all, fields, roots, orphans, hasOrphans)
    // (See "Orphan Errors" section below for more info.)
    output: {
      // determine when to console ("debug" or "error")
      console: ({ hasOrphans }) =>
        // facilitate local debugging of form validation
        (import.meta.env.DEV && { type: 'debug' }) ||
        // console error for reporting on prod
        (hasOrphans && { type: 'error' }),

      // callback to determine when to throw an error based on field errors
      throw: ({ hasOrphans }) =>
        // bring attention to orphans locally
        import.meta.env.DEV && hasOrphans,
    },
  },
};

Provider

Add the context provider to your global provider stack.

<RhfUtilsClientForZodContextProvider config={rhfUtilsClientConfig}>
  {children}
</RhfUtilsClientForZodContextProvider>

Currently, only zod is supported.

Form

<RhfUtilsZodForm
  schema={loginFormSchema}
  defaultValues={{
    email: '',
  }}
  // cancel handler (passed to `Children` below)
  // execution routed through `RhfUtilsClientConfig.useCanFormBeCancelled`, if provided
  onCancel={handleCancel}
  // submit handler
  onSubmit={async (
    data, //    schema output
    context, // UseRhfUtilsFormOnSubmitContext (id, ref, rhf context (without proxy formState), utils options, schema-typed FormSubmitError class)
    event, //   SubmitEvent
  ) => {
    await loginService(data);
    handleSuccess();
  }}
  // handle error declaratively (i.e., no throw/catch)
  onSubmitError={({
    error, //   unknown
    context, // UseRhfUtilsFormOnSubmitErrorContext (id, ref, rhf context (without proxy formState), utils options, `FormSubmitFieldErrors` from `onSubmitErrorUnknown`)
    event, //   SubmitEvent
  }) => {
    handleError(error);
  }}
  // fields
  Children={({
    // UseRhfUtilsFormChildrenProps
    formId, //          unique id string
    formRef, //         ref
    context, //         rhf UseFormReturn (without proxy `formState`)
    options, //         RhfUtilsFormOptions
    Controller, //      schema-typed rhf controller
    FormSubmitError, // schema-typed error class
    onCancel, //        wrapped cancel handler from above
  }) => (
    <>
      <Controller
        name="email" // schema-typed field name
        render={({ field, formState: { isSubmitting } }) => (
          <label>
            Email
            <input {...field} disabled={isSubmitting} />
            <ErrorMessage path={field.name} />
          </label>
        )}
      />

      <button type="button" onClick={onCancel}>
        Cancel
      </button>
      <button type="submit">Login</button>
    </>
  )}
  // form-specific options/overrides (merged with defaults)
  rhf={{
    mode: 'onBlur',
  }}
  utils={{
    submitOnChange: true,
    // custom option props
    // (see "Extend RhfUtilsFormOptions" section)
    enableMyOptionalFormHook: true,
  }}
  form={{
    // class names are merged together with global defaults
    className: 'my-special-form-class',
  }}
/>

Form Children

Children prop takes a component which is rendered as a child of the form (and, if supplied, of RhfUtilsClientConfig.FormChildrenWrapper). It receives UseRhfUtilsFormChildrenProps as props, including a type-safe Controller component.

If you prefer to define your Children component as standalone, you will need to specify any dependencies as props (e.g., onEvent callback):

const Children: RhfUtilsUseFormChildrenZodFC<
  typeof schema,
  'cancelable', // expects cancel handler
  { onEvent: () => void } // other props (if required)
> = ({ ... }) => {};

// or

function Children({ ... }: RhfUtilsUseFormChildrenZodProps<
  typeof schema,
  'cancelable', // expects cancel handler
  { onEvent: () => void } // other props (if required)
>) {}

And pass other props manually, if applicable:

<RhfUtilsZodForm
  Children={(rhfUtilsZodFormChildrenProps) => (
    <Children
      {...rhfUtilsZodFormChildrenProps}
      props={{ onEvent: handleEvent }}
    />
  )}
/>

Form Component Hierarchy

RhfUtilsZodForm renders as:

<ReactHookForm.FormProvider> // standard rhf provider
  <RhfUtilsProviders> // rhf utils internal providers
    <RhfUtilsClientConfig.FormComponent> // from global config (or default)
      <RhfUtilsClientConfig.FormChildrenWrapper> // from global config (if provided)
        <RhfUtilsZodForm.Children /> // form instance component prop
      </RhfUtilsClientConfig.FormChildrenWrapper>
    </RhfUtilsClientConfig.FormComponent>
  <RhfUtilsProviders>
</ReactHookForm.FormProvider>

FormSubmitError

This is an Error-based class that you can use to throw a schema-typed error in your submit handler.

(Internally, it uses FormSubmitFieldErrors type's structure, which is a flat, simplified version of RHF's FieldErrors. It differs from FlatFieldError only in that it is narrower. It allows field names from your schema and root.${string} keys. And only type (optional) and message props for error.)

Example

<RhfUtilsZodForm
  onSubmit={async (data, { FormSubmitError }) => {
    if (isProblem(data))
      throw new FormSubmitError({
        'street.address': { message: 'Street address invalid.' },
      });

    await post('/backend');
  }}
/>

Any non-FormSubmitError error thrown from your submit handler (e.g., fetch/axios error) can be transformed by RhfUtilsClientConfig's onSubmitErrorUnknown callback. This takes an unknown error and can return a FormSubmitFieldErrors object, which is merged into RHF's form state errors.

Most common use case will be transforming backend errors to frontend shape.

RhfUtilsFormOptions

These built-in options can be set globally and/or per form.

type RhfUtilsFormOptions = {
  /** Stop propagation of submit event. */
  stopSubmitPropagation?: boolean;

  /**
   * Request submit via listener on form change.
   * - `true`: no debounce
   * - number: milliseconds to debounce
   */
  submitOnChange?: boolean | number;

  /**
   * Reset form values and state (e.g., isDirty, etc.) after submit -- on success and/or error.
   * - `defaults`: reset current values to defaults (e.g., clear form)
   * - `current`: reset defaults to current values (keep current values)
   */
  resetOnSubmitted?: {
    success?: { values: 'defaults' | 'current' };
    error?: { values: 'defaults' };
  };

  /** Control dev tool options. (Lazy-loaded when truthy value supplied.) */
  devTool?: boolean | Pick<DevtoolUIProps, 'placement' | 'styles'>;
};

If you need access to options deeper in your component structure, use useRhfUtilsContext to receive RhfUtilsContext object, which includes formId, formRef, and options settings.

Use useRhfUtilsContextRequestSubmit hook to get requestSubmit function for current form ref in context. This is useful when you need to trigger form submission programatically.

Extend RhfUtilsFormOptions

Extend RhfUtilsFormOptions with custom options, which get passed to RhfUtilsClientConfig's ChildrenWrapper and RhfUtilsZodForm's Children components via options prop. These can take any shape, and allow you to override your own functionality at form-level.

import '@paragrav/rhf-utils';

declare module '@paragrav/rhf-utils' {
  export interface Register {
    RhfUtilsFormOptions: {
      /** Custom props for your custom options/hooks/behaviors. */
      enableMyOptionalFormHook?: boolean;
      configMyOptionalFormHook?: MyCustomFormHookConfig;
    };
  }
}

Field Errors

FlatFieldErrors

FlatFieldErrors type is a flattened, simplified version of RHF's FieldErrors. Keys represent flattened, dot-notation field paths.

Use useFlatFieldErrorsContext() hook, which returns an object with errors grouped by all, fields, roots, orphans records, and boolean values for hasErrors and hasOrphans.

Output

For the purposes of debugging and/or logging, you can configure when form state errors are outputted (i.e., console and/or thrown) via RhfUtilsClientConfig.fieldErrors.output (example at the top).

Orphan Errors

The concept of an "orphan" error is any errant schema property that could prohibit users from submitting a valid form because its input is missing or non-existent.

Programatically, an "orphan" is any form state error that meets ALL of the following criteria:

• non-field -- i.e., no RHF-supplied ref on FieldError object
• non-root -- i.e., not root or root.${string} path
• no corresponding "marker" in DOM (i.e., RhfUtilsNonFieldErrorMarker)

This is because:

• field errors (with refs) are assumed to be displayed next to their respective input
• root errors (non-field, without refs) are assumed to always be listed for display
• all other errors must be marked as displayed to distinguish from being an orphan

See RhfUtilsNonFieldErrorMarker section below for more information about when and why marker is needed.

Using orphan errors

Detected orphans can be accessed via any of the following:

• RhfUtilsClientConfig.fieldErrors.output -- e.g., config per environment:
  • development: throw to facilitate discovery and debugging
  • production: console.error to facilitate reporting
• useFlatFieldErrorsContext() hook
  • returns an object with list of errors grouped by all, fields (with ref), roots, orphans records, and includes computed booleans hasErrors and hasOrphans
• boolean value from useFlatFieldErrorsContextHasOnlyOrphans

RhfUtilsNonFieldErrorMarker

If you don't need orphan detection, you can skip this section. By default, orphan detection still occurs but doesn't otherwise do anything.

To get accurate orphan detection, you must use RhfUtilsNonFieldErrorMarker when displaying any non-root non-field errors. (Example further below.)

There is little harm in including it consistently for all individual errors displayed. (DOM traversal to find marker only occurs if error is non-field AND non-root, which is not typical.)

When is the marker required? (example of non-root non-field error)

A typical example is a field array with a required minimum number of items -- e.g., items: z.array(...).min(1).

When there are zero items, the error is non-field and non-root. You would probably display this error (manually) near the field array, using something like RHF's ErrorMessage component.

In order to NOT detect this as an orphan, it must be explicitly "marked" as displayed using RhfUtilsNonFieldErrorMarker.

You should incorporate RhfUtilsNonFieldErrorMarker into your own component library's error message display component.

<RhfUtilsNonFieldErrorMarker path="items" />

If you include the marker in bulk error lists, it will defeat the purpose of the marker. Only use marker for individual errors. Therefore, if you are ONLY listing a summary of all errors, without individual displays, you will need to use the marker manually.

Other Features

Form Groups (0.7kB min+gzip)

Sometimes you need to group multiple forms together.

Use case: disable parent form when any child is "busy"; disable all children when parent is "busy".

Use FormGroupContextProvider to wrap your children and parent forms.

<FormGroupContextProvider>
  <ChildForm1 />
  <ChildForm2 />
  <ParentForm />
</FormGroupContextProvider>

In your parent form, use the hook useFormGroupParentTracker, which returns boolean value indicating whether any child forms is busy.

In children forms, there are two options. You can choose to consider form "busy" when:

• isSubmitting is true by using useFormGroupChildIsSubmittingTracker hook
• it is mounted by using useFormGroupChildIsMountedTracker hook

Both hooks return boolean value indicating whether parent form is busy.

TRPC.io Utils (0.4kB min+gzip)

trpcClientErrorToFormSubmitFieldErrorsSchemaTransformer

zod-based schema for transforming TRPCClientErrorLike<AnyRouter> server errors to FormSubmitFieldErrors.

makeOnSubmitTrpcClientErrorHandler

HOF to make a onSubmitErrorUnknown handler for TRPC.io server errors (with fallback callback for non-TRPC errors).

  onSubmitErrorUnknown: makeOnSubmitTrpcClientErrorHandler((error) => {
    // non-trpc error
  }),

Other

SafeFieldValues

This library uses SafeFieldValues type which uses unknown instead of any.

Peer dependencies

• react
• react-dom
• react-hook-form
• @hookform/resolvers
• @hookform/devtools (optional)
• zod
• flat (805B min+gzip)