</> getFieldState:
(name: string, formState?: Object) => ({isDirty, isTouched, invalid, error})
This method is introduced in react-hook-form (v7.25.0) to return individual field state. It's useful in case you are trying to retrieve nested field state in a typesafe way.
Props
Name | Type | Description |
---|---|---|
name | string | registered field name. |
formState | object | This is an optional prop, which is only required if formState is not been read/subscribed from the useForm , useFormContext or useFormState . Read rules for more information |
Return
Name | Type | Description |
---|---|---|
isDirty | boolean | field is modified. Condition: subscribe to dirtyFields . |
isTouched | boolean | field has received a focus and blur event. Condition: subscribe to touchedFields . |
invalid | boolean | field is not valid. Condition: subscribe to errors . |
error | undefined | FieldError | field error object. Condition: subscribe to errors . |
-
name needs to match a registered field name.
getFieldState("test")getFieldState("test") // ✅ register input and return field stategetFieldState("non-existent-name") // ❌ will return state as false and error as undefined -
getFieldState
works by subscribing to the form state update, and you can subscribe to the formState in the following ways:-
You can subscribe at the
useForm
,useFormContext
oruseFormState
. This is will establish the form state subscription andgetFieldState
second argument will no longer be required.const {register,formState: { isDirty },} = useForm()register("test")getFieldState("test") // ✅const { isDirty } = useFormState()register("test")getFieldState("test") // ✅const {register,formState: { isDirty },} = useFormContext()register("test")getFieldState("test") // ✅ -
When form state subscription is not setup, you can pass the entire
formState
as the second optional argument by following the example below:const { register } = useForm()register("test")const { isDirty } = getFieldState("test") // ❌ formState isDirty is not subscribed at useFormconst { register, formState } = useForm()const { isDirty } = getFieldState("test", formState) // ✅ formState.isDirty subscribedconst { formState } = useFormContext()const { touchedFields } = getFieldState("test", formState) // ✅ formState.touchedFields subscribed
-
Examples
import * as React from "react"import { useForm } from "react-hook-form"export default function App() {const {register,getFieldState,formState: { isDirty, isValid },} = useForm({mode: "onChange",defaultValues: {firstName: "",},})// you can invoke before render or within the render functionconst fieldState = getFieldState("firstName")return (<form><input {...register("firstName", { required: true })} />{" "}<p>{getFieldState("firstName").isDirty && "dirty"}</p>{" "}<p>{getFieldState("firstName").isTouched && "touched"}</p><buttontype="button"onClick={() => console.log(getFieldState("firstName"))}>field state</button></form>)}
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