| import React from 'react'; |
| import { useForm, useWatch } from 'react-hook-form'; |
|
|
| function useInputCache(values, causeField, effectField, callback) { |
| const [effectCache, setEffectCache] = React.useState(values[effectField]); |
|
|
| const evaluateRegStatus = (vals, currentState) => { |
| |
| const isRegistered = !!vals[causeField]; |
| return { |
| isRegistered, |
| registrationStatusChanged: isRegistered !== currentState, |
| hasValue: vals[effectField] !== undefined, |
| }; |
| }; |
|
|
| |
| const currentRegState = React.useRef(false); |
|
|
| React.useEffect(() => { |
| const { isRegistered, registrationStatusChanged, hasValue } = |
| evaluateRegStatus(values, currentRegState.current); |
|
|
| if (registrationStatusChanged && hasValue) { |
| if (isRegistered && !!effectCache) { |
| console.debug('Deploying cache'); |
| callback(effectField, effectCache); |
| } else if (!isRegistered) { |
| console.debug('Caching before unmount'); |
| setEffectCache(values[effectField]); |
| } |
| currentRegState.current = !!isRegistered; |
| } |
| |
| }, [values, causeField, effectField, callback]); |
| } |
|
|
| export default function App() { |
| const { register, handleSubmit, setValue, control } = useForm({ |
| mode: 'onChange', |
| defaultValues: { |
| name: '', |
| check: false, |
| optionalText: '', |
| }, |
| }); |
|
|
| const values = useWatch({ |
| control, |
| }); |
| useInputCache(values, 'check', 'optionalText', setValue); |
|
|
| return ( |
| <div className="App"> |
| <h1>Here's a form with conditional fields.</h1> |
| <form onSubmit={handleSubmit(console.log)}> |
| <input |
| name={'name'} |
| type={'text'} |
| ref={register({ required: true, min: 3 })} |
| placeholder={'Enter a name'} |
| /> |
| <br /> |
| <label htmlFor={'check'}> |
| toggle field: |
| <input |
| name={'check'} |
| type={'checkbox'} |
| ref={register({ required: true })} |
| /> |
| </label> |
| <br /> |
| {values.check && ( |
| <input |
| name={'optionalText'} |
| ref={register({ required: false })} |
| placeholder={'Mandatory when check=true'} |
| /> |
| )} |
| </form> |
| </div> |
| ); |
| } |
|
|
