Strongly typed form values for Flow and Typescript

package.json

@@ -61,7 +61,7 @@
     "eslint-plugin-react": "^7.13.0",
     "eslint-plugin-react-hooks": "^1.6.0",
     "fast-deep-equal": "^2.0.1",
-    "final-form": "^4.13.0",
+    "final-form": "^4.14.0",
     "flow-bin": "^0.98.1",
     "glow": "^1.2.2",
     "husky": "^2.3.0",
@@ -88,7 +88,7 @@
     "typescript": "^3.4.5"
   },
   "peerDependencies": {
-    "final-form": "^4.13.0",
+    "final-form": "^4.14.0",
     "react": "^16.8.0"
   },
   "lint-staged": {

src/FormSpy.js

@@ -2,13 +2,20 @@
 import * as React from 'react'
 import renderComponent from './renderComponent'
 import type { FormSpyPropsWithForm as Props, FormSpyRenderProps } from './types'
-import type { FormApi } from 'final-form'
+import type { FormApi, FormValuesShape } from 'final-form'
 import isSyntheticEvent from './isSyntheticEvent'
 import useFormState from './useFormState'
-import ReactFinalFormContext from './context'
+import getContext from './getContext'
 
-const FormSpy = ({ onChange, subscription, ...rest }: Props) => {
-  const reactFinalForm: ?FormApi = React.useContext(ReactFinalFormContext)
+function FormSpy<FormValues: FormValuesShape>({
+  onChange,
+  subscription,
+  ...rest
+}: Props<FormValues>) {
+  const ReactFinalFormContext = getContext<FormValues>()
+  const reactFinalForm: ?FormApi<FormValues> = React.useContext(
+    ReactFinalFormContext
+  )
   if (!reactFinalForm) {
     throw new Error('FormSpy must be used inside of a ReactFinalForm component')
   }
@@ -17,7 +24,7 @@ const FormSpy = ({ onChange, subscription, ...rest }: Props) => {
     return null
   }
 
-  const renderProps: FormSpyRenderProps = {
+  const renderProps: FormSpyRenderProps<FormValues> = {
     form: {
       ...reactFinalForm,
       reset: eventOrValues => {

src/ReactFinalForm.js

@@ -10,6 +10,7 @@ import type {
   Config,
   FormSubscription,
   FormState,
+  FormValuesShape,
   Unsubscribe
 } from 'final-form'
 import type { FormProps as Props } from './types'
@@ -19,10 +20,10 @@ import useConstant from './useConstant'
 import shallowEqual from './shallowEqual'
 import isSyntheticEvent from './isSyntheticEvent'
 import type { FormRenderProps } from './types.js.flow'
-import ReactFinalFormContext from './context'
+import getContext from './getContext'
 import useLatest from './useLatest'
 
-export const version = '6.0.1'
+export const version = '6.1.0'
 
 const versions = {
   'final-form': ffVersion,
@@ -37,7 +38,7 @@ export const all: FormSubscription = formSubscriptionItems.reduce(
   {}
 )
 
-const ReactFinalForm = ({
+function ReactFinalForm<FormValues: FormValuesShape>({
   debug,
   decorators,
   destroyOnUnregister,
@@ -50,8 +51,9 @@ const ReactFinalForm = ({
   validate,
   validateOnBlur,
   ...rest
-}: Props) => {
-  const config: Config = {
+}: Props<FormValues>) {
+  const ReactFinalFormContext = getContext<FormValues>()
+  const config: Config<FormValues> = {
     debug,
     destroyOnUnregister,
     initialValues,
@@ -62,16 +64,16 @@ const ReactFinalForm = ({
     validateOnBlur
   }
 
-  const form: FormApi = useConstant(() => {
-    const f = createForm(config)
+  const form: FormApi<FormValues> = useConstant(() => {
+    const f = createForm<FormValues>(config)
     f.pauseValidation()
     return f
   })
 
   // synchronously register and unregister to query form state for our subscription on first render
-  const [state, setState] = React.useState<FormState>(
-    (): FormState => {
-      let initialState: FormState = {}
+  const [state, setState] = React.useState<FormState<FormValues>>(
+    (): FormState<FormValues> => {
+      let initialState: FormState<FormValues> = {}
       form.subscribe(state => {
         initialState = state
       }, subscription)()
@@ -81,7 +83,7 @@ const ReactFinalForm = ({
 
   // save a copy of state that can break through the closure
   // on the shallowEqual() line below.
-  const stateRef = useLatest<FormState>(state)
+  const stateRef = useLatest<FormState<FormValues>>(state)
 
   React.useEffect(() => {
     // We have rendered, so all fields are no registered, so we can unpause validation
@@ -170,7 +172,7 @@ const ReactFinalForm = ({
     return form.submit()
   }
 
-  const renderProps: FormRenderProps = {
+  const renderProps: FormRenderProps<FormValues> = {
     // assign to force Flow check
     ...state,
     form: {

src/getContext.js

@@ -0,0 +1,14 @@
+// @flow
+import * as React from 'react'
+import type { FormApi, FormValuesShape } from 'final-form'
+
+let instance: React.Context<?FormApi<any>>
+
+export default function getContext<
+  FormValues: FormValuesShape
+>(): React.Context<FormApi<FormValues>> {
+  if (!instance) {
+    instance = React.createContext<?FormApi<FormValues>>()
+  }
+  return ((instance: any): React.Context<FormApi<FormValues>>)
+}

src/index.js

@@ -1,9 +1,12 @@
 // @flow
+import Form from './ReactFinalForm'
+import FormSpy from './FormSpy'
 export { default as Field } from './Field'
 export { default as Form, version } from './ReactFinalForm'
 export { default as FormSpy } from './FormSpy'
-export { default as ReactFinalFormContext } from './context'
 export { default as useField } from './useField'
 export { default as useFormState } from './useFormState'
 export { default as useForm } from './useForm'
-export { default as context } from './context'
+export function withTypes() {
+  return { Form, FormSpy }
+}

src/index.js.flow

@@ -1,6 +1,6 @@
 // @flow
 import * as React from 'react'
-import type { FormApi, FormState } from 'final-form'
+import type { FormApi, FormState, FormValuesShape } from 'final-form'
 import type {
   FieldProps,
   FieldRenderProps,
@@ -20,12 +20,20 @@ export type {
 } from './types'
 
 declare export var Field: React.ComponentType<FieldProps>
-declare export var Form: React.ComponentType<FormProps>
-declare export var FormSpy: React.ComponentType<FormSpyProps>
-declare export var useForm: (componentName?: string) => FormApi
-declare export var useFormState: UseFormStateParams => ?FormState
+declare export var Form: React.ComponentType<FormProps<Object>>
+declare export var FormSpy: React.ComponentType<FormSpyProps<Object>>
+declare export function useForm<FormValues: FormValuesShape>(
+  componentName?: string
+): FormApi<FormValues>
+declare export function useFormState<FormValues>(
+  params: UseFormStateParams<FormValues>
+): ?FormState<FormValues>
 declare export var useField: (
   name: string,
   config: UseFieldConfig
 ) => FieldRenderProps
+declare export function withTypes<FormValues: FormValuesShape>(): {
+  Form: React.ComponentType<FormProps<FormValues>>,
+  FormSpy: React.ComponentType<FormSpyProps<FormValues>>
+}
 declare export var version: string

src/types.js.flow

@@ -6,14 +6,15 @@ import type {
   Decorator,
   FormState,
   FormSubscription,
+  FormValuesShape,
   FieldSubscription,
   FieldValidator
 } from 'final-form'
 
 type SupportedInputs = 'input' | 'select' | 'textarea'
 
-export type ReactContext = {
-  reactFinalForm: FormApi
+export type ReactContext<FormValues: FormValuesShape> = {
+  reactFinalForm: FormApi<FormValues>
 }
 
 export type FieldInputProps = {
@@ -49,27 +50,27 @@ export type FieldRenderProps = {
   }
 }
 
-export type FormRenderProps = {
+export type FormRenderProps<FormValues: FormValuesShape> = {
   handleSubmit: (?SyntheticEvent<HTMLFormElement>) => ?Promise<?Object>,
-  form: FormApi
-} & FormState
+  form: FormApi<FormValues>
+} & FormState<FormValues>
 
-export type FormSpyRenderProps = {
-  form: FormApi
-} & FormState
+export type FormSpyRenderProps<FormValues: FormValuesShape> = {
+  form: FormApi<FormValues>
+} & FormState<FormValues>
 
 export type RenderableProps<T> = {
   component?: React.ComponentType<*> | SupportedInputs,
   children?: ((props: T) => React.Node) | React.Node,
   render?: (props: T) => React.Node
 }
 
-export type FormProps = {
+export type FormProps<FormValues: FormValuesShape> = {
   subscription?: FormSubscription,
-  decorators?: Decorator[],
+  decorators?: Decorator<FormValues>[],
   initialValuesEqual?: (?Object, ?Object) => boolean
-} & Config &
-  RenderableProps<FormRenderProps>
+} & Config<FormValues> &
+  RenderableProps<FormRenderProps<FormValues>>
 
 export type UseFieldConfig = {
   afterSubmit?: () => void,
@@ -95,14 +96,16 @@ export type FieldProps = UseFieldConfig & {
   name: string
 } & RenderableProps<FieldRenderProps>
 
-export type UseFormStateParams = {
-  onChange?: (formState: FormState) => void,
+export type UseFormStateParams<FormValues: FormValuesShape> = {
+  onChange?: (formState: FormState<FormValues>) => void,
   subscription?: FormSubscription
 }
 
-export type FormSpyProps = UseFormStateParams &
-  RenderableProps<FormSpyRenderProps>
+export type FormSpyProps<
+  FormValues: FormValuesShape
+> = UseFormStateParams<FormValues> &
+  RenderableProps<FormSpyRenderProps<FormValues>>
 
-export type FormSpyPropsWithForm = {
-  reactFinalForm: FormApi
-} & FormSpyProps
+export type FormSpyPropsWithForm<FormValues: FormValuesShape> = {
+  reactFinalForm: FormApi<FormValues>
+} & FormSpyProps<FormValues>

src/useField.js

@@ -1,7 +1,12 @@
 // @flow
 import * as React from 'react'
 import { fieldSubscriptionItems } from 'final-form'
-import type { FieldSubscription, FieldState, FormApi } from 'final-form'
+import type {
+  FieldSubscription,
+  FieldState,
+  FormApi,
+  FormValuesShape
+} from 'final-form'
 import type { UseFieldConfig, FieldInputProps, FieldRenderProps } from './types'
 import isReactNative from './isReactNative'
 import getValue from './getValue'
@@ -18,7 +23,7 @@ const defaultFormat = (value: ?any, name: string) =>
 const defaultParse = (value: ?any, name: string) =>
   value === '' ? undefined : value
 
-const useField = (
+function useField<FormValues: FormValuesShape>(
   name: string,
   {
     afterSubmit,
@@ -38,8 +43,8 @@ const useField = (
     validateFields,
     value: _value
   }: UseFieldConfig = {}
-): FieldRenderProps => {
-  const form: FormApi = useForm('useField')
+): FieldRenderProps {
+  const form: FormApi<FormValues> = useForm<FormValues>('useField')
 
   const validateRef = useLatest(validate)
 

src/useForm.js

@@ -1,10 +1,13 @@
 // @flow
 import * as React from 'react'
-import type { FormApi } from 'final-form'
-import ReactFinalFormContext from './context'
+import type { FormApi, FormValuesShape } from 'final-form'
+import getContext from './getContext'
 
-const useForm = (componentName?: string): FormApi => {
-  const form: ?FormApi = React.useContext(ReactFinalFormContext)
+function useForm<FormValues: FormValuesShape>(
+  componentName?: string
+): FormApi<FormValues> {
+  const ReactFinalFormContext = getContext<FormValues>()
+  const form: ?FormApi<FormValues> = React.useContext(ReactFinalFormContext)
   if (!form) {
     throw new Error(
       `${componentName || 'useForm'} must be used inside of a <Form> component`

src/useFormState.js

@@ -1,21 +1,21 @@
 // @flow
 import * as React from 'react'
 import type { UseFormStateParams } from './types'
-import type { FormState, FormApi } from 'final-form'
+import type { FormState, FormApi, FormValuesShape } from 'final-form'
 import { all } from './ReactFinalForm'
 import useForm from './useForm'
 
-const useFormState = ({
+function useFormState<FormValues: FormValuesShape>({
   onChange,
   subscription = all
-}: UseFormStateParams = {}): FormState => {
-  const form: FormApi = useForm('useFormState')
+}: UseFormStateParams<FormValues> = {}): FormState<FormValues> {
+  const form: FormApi<FormValues> = useForm<FormValues>('useFormState')
   const firstRender = React.useRef(true)
 
   // synchronously register and unregister to query field state for our subscription on first render
-  const [state, setState] = React.useState<FormState>(
-    (): FormState => {
-      let initialState: FormState = {}
+  const [state, setState] = React.useState<FormState<FormValues>>(
+    (): FormState<FormValues> => {
+      let initialState: FormState<FormValues> = {}
       form.subscribe(state => {
         initialState = state
       }, subscription)()