Make FormControl externally extensible (via hook)

.changeset/sweet-turtles-applaud.md

@@ -0,0 +1,7 @@
+---
+"@primer/react": minor
+---
+
+Allow consumers to make components that are compatible with `FormControl` by reading forwarded props in from the `useFormControlForwardedProps` hook
+
+<!-- Changed components: FormControl -->

src/FormControl/FormControl.tsx

@@ -10,14 +10,14 @@ import Textarea from '../Textarea'
 import {CheckboxOrRadioGroupContext} from '../internal/components/CheckboxOrRadioGroup'
 import ValidationAnimationContainer from '../internal/components/ValidationAnimationContainer'
 import {get} from '../constants'
-import InlineAutocomplete from '../drafts/InlineAutocomplete'
 import {useSlots} from '../hooks/useSlots'
 import {SxProp} from '../sx'
-import {useSSRSafeId} from '../utils/ssr'
+import {useId} from '../hooks/useId'
 import FormControlCaption from './_FormControlCaption'
 import FormControlLabel from './_FormControlLabel'
 import FormControlLeadingVisual from './_FormControlLeadingVisual'
 import FormControlValidation from './_FormControlValidation'
+import {FormControlContextProvider} from './_FormControlContext'
 
 export type FormControlProps = {
   children?: React.ReactNode
@@ -40,13 +40,6 @@ export type FormControlProps = {
   layout?: 'horizontal' | 'vertical'
 } & SxProp
 
-export interface FormControlContext extends Pick<FormControlProps, 'disabled' | 'id' | 'required'> {
-  captionId?: string
-  validationMessageId?: string
-}
-
-export const FormControlContext = React.createContext<FormControlContext>({})
-
 const FormControl = React.forwardRef<HTMLDivElement, FormControlProps>(
   ({children, disabled: disabledProp, layout = 'vertical', id: idProp, required, sx}, ref) => {
     const [slots, childrenWithoutSlots] = useSlots(children, {
@@ -55,19 +48,10 @@ const FormControl = React.forwardRef<HTMLDivElement, FormControlProps>(
       leadingVisual: FormControlLeadingVisual,
       validation: FormControlValidation,
     })
-    const expectedInputComponents = [
-      Autocomplete,
-      Checkbox,
-      Radio,
-      Select,
-      TextInput,
-      TextInputWithTokens,
-      Textarea,
-      InlineAutocomplete,
-    ]
+    const expectedInputComponents = [Autocomplete, Checkbox, Radio, Select, TextInput, TextInputWithTokens, Textarea]
     const choiceGroupContext = useContext(CheckboxOrRadioGroupContext)
     const disabled = choiceGroupContext.disabled || disabledProp
-    const id = useSSRSafeId(idProp)
+    const id = useId(idProp)
     const validationMessageId = slots.validation ? `${id}-validationMessage` : undefined
     const captionId = slots.caption ? `${id}-caption` : undefined
     const validationStatus = slots.validation?.props.variant
@@ -130,7 +114,7 @@ const FormControl = React.forwardRef<HTMLDivElement, FormControlProps>(
     const isLabelHidden = slots.label?.props.visuallyHidden
 
     return (
-      <FormControlContext.Provider
+      <FormControlContextProvider
         value={{
           captionId,
           disabled,
@@ -222,7 +206,7 @@ const FormControl = React.forwardRef<HTMLDivElement, FormControlProps>(
             {slots.caption}
           </Box>
         )}
-      </FormControlContext.Provider>
+      </FormControlContextProvider>
     )
   },
 )

src/FormControl/_FormControlCaption.tsx

@@ -1,10 +1,10 @@
 import React from 'react'
 import InputCaption from '../internal/components/InputCaption'
 import {SxProp} from '../sx'
-import {FormControlContext} from './FormControl'
+import {useFormControlContext} from './_FormControlContext'
 
 const FormControlCaption: React.FC<React.PropsWithChildren<{id?: string} & SxProp>> = ({children, sx, id}) => {
-  const {captionId, disabled} = React.useContext(FormControlContext)
+  const {captionId, disabled} = useFormControlContext()
   return (
     <InputCaption id={id || captionId || ''} disabled={disabled} sx={sx}>
       {children}

src/FormControl/_FormControlContext.tsx

@@ -0,0 +1,51 @@
+import {createContext, useContext} from 'react'
+import {FormValidationStatus} from '../utils/types/FormValidationStatus'
+import {FormControlProps} from './FormControl'
+
+interface FormControlContext extends Pick<FormControlProps, 'disabled' | 'id' | 'required'> {
+  captionId?: string
+  validationMessageId?: string
+  validationStatus?: FormValidationStatus
+}
+
+const FormControlContext = createContext<FormControlContext | null>(null)
+
+export const FormControlContextProvider = FormControlContext.Provider
+
+/** This is the private/internal interface for subcomponents of `FormControl`. */
+export function useFormControlContext(): FormControlContext {
+  return useContext(FormControlContext) ?? {}
+}
+
+interface FormControlForwardedProps extends Omit<FormControlContext, 'captionId' | 'validationMessageId'> {
+  ['aria-describedby']?: string
+}
+
+/**
+ * Make any component compatible with `FormControl`'s automatic wiring up of accessibility attributes & validation by
+ * reading the props from this hook and merging them with the passed-in props. If used outside of `FormControl`, this
+ * hook has no effect.
+ *
+ * @param externalProps The external props passed to this component. If provided, these props will be merged with the
+ * `FormControl` props, with external props taking priority.
+ */
+export function useFormControlForwardedProps<P>(externalProps: P): P & FormControlForwardedProps
+/**
+ * Make any component compatible with `FormControl`'s automatic wiring up of accessibility attributes & validation by
+ * reading the props from this hook and handling them / assigning them to the underlying form control. If used outside
+ * of `FormControl`, this hook has no effect.
+ */
+export function useFormControlForwardedProps(): FormControlForwardedProps
+export function useFormControlForwardedProps(externalProps: FormControlForwardedProps = {}) {
+  const context = useContext(FormControlContext)
+  if (!context) return externalProps
+
+  return {
+    disabled: context.disabled,
+    id: context.id,
+    required: context.required,
+    validationStatus: context.validationStatus,
+    ['aria-describedby']: [context.validationMessageId, context.captionId].filter(Boolean).join(' ') || undefined,
+    ...externalProps,
+  }
+}

src/FormControl/_FormControlLabel.tsx

@@ -1,7 +1,7 @@
 import React from 'react'
 import InputLabel from '../internal/components/InputLabel'
 import {SxProp} from '../sx'
-import {FormControlContext} from './FormControl'
+import {useFormControlContext} from './_FormControlContext'
 
 export type Props = {
   /**
@@ -14,7 +14,7 @@ export type Props = {
 const FormControlLabel: React.FC<
   React.PropsWithChildren<{htmlFor?: string} & React.ComponentProps<typeof InputLabel> & Props>
 > = ({as, children, htmlFor, id, visuallyHidden, sx, ...props}) => {
-  const {disabled, id: formControlId, required} = React.useContext(FormControlContext)
+  const {disabled, id: formControlId, required} = useFormControlContext()
 
   /**
    * Ensure we can pass through props correctly, since legend/span accept no defined 'htmlFor'

src/FormControl/_FormControlLeadingVisual.tsx

@@ -2,10 +2,10 @@ import React from 'react'
 import Box from '../Box'
 import {get} from '../constants'
 import {SxProp} from '../sx'
-import {FormControlContext} from './FormControl'
+import {useFormControlContext} from './_FormControlContext'
 
 const FormControlLeadingVisual: React.FC<React.PropsWithChildren<SxProp>> = ({children, sx}) => {
-  const {disabled, captionId} = React.useContext(FormControlContext)
+  const {disabled, captionId} = useFormControlContext()
   return (
     <Box
       color={disabled ? 'fg.muted' : 'fg.default'}

src/FormControl/_FormControlValidation.tsx

@@ -2,7 +2,7 @@ import React from 'react'
 import InputValidation from '../internal/components/InputValidation'
 import {SxProp} from '../sx'
 import {FormValidationStatus} from '../utils/types/FormValidationStatus'
-import {FormControlContext} from './FormControl'
+import {useFormControlContext} from './_FormControlContext'
 
 export type FormControlValidationProps = {
   variant: FormValidationStatus
@@ -15,7 +15,7 @@ const FormControlValidation: React.FC<React.PropsWithChildren<FormControlValidat
   sx,
   id,
 }) => {
-  const {validationMessageId} = React.useContext(FormControlContext)
+  const {validationMessageId} = useFormControlContext()
   return (
     <InputValidation validationStatus={variant} id={id || validationMessageId || ''} sx={sx}>
       {children}

src/FormControl/index.ts

@@ -1 +1,2 @@
+export {useFormControlForwardedProps} from './_FormControlContext'
 export {default} from './FormControl'

src/FormControl/useFormControlForwardedProps.stories.tsx

@@ -0,0 +1,67 @@
+import React from 'react'
+import {Meta} from '@storybook/react'
+import {BaseStyles, FormControl, ThemeProvider, theme, useFormControlForwardedProps} from '..'
+
+export default {
+  title: 'Hooks/useFormControlForwardedProps',
+  decorators: [
+    Story => {
+      return (
+        <ThemeProvider theme={theme}>
+          <BaseStyles>
+            <Story />
+          </BaseStyles>
+        </ThemeProvider>
+      )
+    },
+  ],
+  argTypes: {
+    disabled: {
+      type: 'boolean',
+    },
+    required: {
+      type: 'boolean',
+    },
+    label: {
+      type: 'string',
+    },
+    caption: {
+      type: 'string',
+    },
+    type: {
+      control: {
+        type: 'select',
+        description: "Type of the input, showing how the `type` prop can be forwarded to the input's props",
+      },
+      options: ['text', 'number', 'password', 'email', 'search', 'tel', 'url'],
+    },
+  },
+} as Meta
+
+interface ArgTypes {
+  disabled: boolean
+  required: boolean
+  label: string
+  caption: string
+  type: string
+}
+
+/** A custom input that is not a Primer `TextInput` but still supports autowiring with `FormControl`. */
+const CustomInput = (externalProps: {type: string}) => {
+  const props = useFormControlForwardedProps(externalProps)
+  return <input {...props} />
+}
+
+export const AutowiredCustomInput = ({
+  label = 'Custom input',
+  caption = 'This is not a Primer input, but it still has `aria-describedby` and similar attributes applied automatically',
+  required = false,
+  disabled = false,
+  type = 'text',
+}: ArgTypes) => (
+  <FormControl disabled={disabled} required={required}>
+    <FormControl.Label>{label}</FormControl.Label>
+    <CustomInput type={type} />
+    {caption && <FormControl.Caption>{caption}</FormControl.Caption>}
+  </FormControl>
+)

src/__tests__/FormControl.test.tsx

@@ -1,7 +1,17 @@
 import React from 'react'
-import {render} from '@testing-library/react'
+import {render, renderHook} from '@testing-library/react'
 import {axe, toHaveNoViolations} from 'jest-axe'
-import {Autocomplete, Checkbox, FormControl, Select, SSRProvider, Textarea, TextInput, TextInputWithTokens} from '..'
+import {
+  Autocomplete,
+  Checkbox,
+  FormControl,
+  Select,
+  SSRProvider,
+  Textarea,
+  TextInput,
+  TextInputWithTokens,
+  useFormControlForwardedProps,
+} from '..'
 import {MarkGithubIcon} from '@primer/octicons-react'
 expect.extend(toHaveNoViolations)
 
@@ -446,3 +456,53 @@
     })
   })
 })
+
+describe('useFormControlForwardedProps', () => {
+  describe('when used outside FormControl', () => {
+    test('returns empty object when no props object passed', () => {
+      const result = renderHook(() => useFormControlForwardedProps())
+      expect(result.result.current).toEqual({})
+    })
+
+    test('returns passed props object instance when passed', () => {
+      const props = {id: 'test-id'}
+      const result = renderHook(() => useFormControlForwardedProps(props))
+      expect(result.result.current).toBe(props)
+    })
+  })
+
+  test('provides context value when no props object is passed', () => {
+    const id = 'test-id'
+
+    const {result} = renderHook(() => useFormControlForwardedProps(), {
+      wrapper: ({children}) => (
+        <FormControl id={id} disabled required>
+          <FormControl.Label>Label</FormControl.Label>
+          {children}
+        </FormControl>
+      ),
+    })
+
+    expect(result.current.disabled).toBe(true)
+    expect(result.current.id).toBe(id)
+    expect(result.current.required).toBe(true)
+  })
+
+  test('merges with props object, overriding to prioritize props when conflicting', () => {
+    const props = {id: 'override-id', xyz: 'someValue'}
+
+    const {result} = renderHook(() => useFormControlForwardedProps(props), {
+      wrapper: ({children}) => (
+        <FormControl id="form-control-id" disabled>
+          <FormControl.Label>Label</FormControl.Label>
+          {children}
+        </FormControl>
+      ),
+    })
+
+    expect(result.current.disabled).toBe(true)
+    expect(result.current.id).toBe(props.id)
+    expect(result.current.required).toBeFalsy()
+    expect(result.current.xyz).toBe(props.xyz)
+  })
+})

src/drafts/InlineAutocomplete/InlineAutocomplete.tsx

@@ -99,7 +99,6 @@ const InlineAutocomplete = ({
   children,
   tabInsertsSuggestions = false,
   suggestionsPlacement = 'below',
-  // Forward accessibility props so it works with FormControl
   ...forwardProps
 }: InlineAutocompleteProps & React.ComponentProps<'textarea' | 'input'>) => {
   const inputRef = useRef<HTMLInputElement & HTMLTextAreaElement>(null)

src/index.ts

@@ -97,6 +97,7 @@ export type {FilterListProps, FilterListItemProps} from './FilterList'
 export {default as Flash} from './Flash'
 export type {FlashProps} from './Flash'
 export {default as FormControl} from './FormControl'
+export {useFormControlForwardedProps} from './FormControl'
 export {default as Header} from './Header'
 export type {HeaderProps, HeaderItemProps, HeaderLinkProps} from './Header'
 export {default as Heading} from './Heading'