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useController

React hooks for controlled component

useController:
(props?: UseControllerProps) => { field: object, fieldState: object, formState: object }

This custom hook powers Controller. Additionally, it shares the same props and methods as Controller. It's useful for creating reusable Controlled input.

Props

The following table contains information about the arguments for useController.

NameTypeRequiredDescription
nameFieldPath✓Unique name of your input.
controlControlcontrol object provided by invoking useForm. Optional when using FormProvider.
defaultValueunknown

Important: Can not apply undefined to defaultValue or defaultValues at useForm.

  • You need to either set defaultValue at the field-level or useForm's defaultValues. undefined is not a valid value.

  • If your form will invoke reset with default values, you will need to provide useForm with defaultValues.

rulesObject

Validation rules in the same format for register, which includes:

required, min, max, minLength, maxLength, pattern, validate

CodeSandbox 
rules={{ required: true }}
shouldUnregisterboolean = false

Input will be unregistered after unmount and defaultValues will be removed as well.

Return

The following table contains information about properties which useController produces.

stringReact.Ref
Object NameNameTypeDescription
fieldonChange(value: any) => void

A function which sends the input's value to the library.

  • It should be assigned to the onChange prop of the input and value should not be undefined.

  • This prop update formState and you should avoid manually invoke setValue or other API related to field update.

onBlur() => void

A function which sends the input's onBlur event to the library. It should be assigned to the input's onBlur prop.

valueunknown

The current value of the controlled component.

name

Input's name being registered.

ref

A ref used to connect hook form to the input. Assign ref to component's input ref to allow hook form to focus the error input.

fieldStateinvalidboolean

Invalid state for current input.

isTouchedboolean

Touched state for current controlled input.

isDirtyboolean

Dirty state for current controlled input.

errorobject

error for this specific input.

formStateisDirtyboolean

Set to true after the user modifies any of the inputs.

  • Make sure to provide all inputs' defaultValues at the useForm, so hook form can have a single source of truth to compare whether the form is dirty.

  • File typed input will need to be managed at the app level due to the ability to cancel file selection and FileList object.

dirtyFieldsobject

An object with the user-modified fields. Make sure to provide all inputs' defaultValues via useForm, so the library can compare against the defaultValues.

Dirty fields will not represent as isDirty formState, because dirty fields are marked field dirty at field level rather the entire form. If you want to determine the entire form state use isDirty instead.

touchedFieldsobjectAn object containing all the inputs the user has interacted with.
isSubmittedbooleanSet to true after the form is submitted. Will remain true until the reset method is invoked.
isSubmitSuccessfulboolean

Indicate the form was successfully submitted without any Promise rejection or Error been thrown within the handleSubmit callback.

isSubmittingbooleantrue if the form is currently being submitted. false otherwise.
submitCountnumberNumber of times the form was submitted.
isValidboolean
Set to true if the form doesn't have any errors.

Note: isValid is affected by mode at useForm. This state is only applicable with onChange, onTouched, and onBlur mode.

isValidatingbooleanSet to true during validation.
errorsobjectAn object with field errors. There is also an ErrorMessage component to retrieve error message easily.

Examples

CodeSandbox 
import React from "react";
import { TextField } from "@material-ui/core";
import { useController, useForm } from "react-hook-form";

function Input({ control, name }) {
  const { control } = useForm();
  const {
    field: { onChange, onBlur, name, value, ref },
    fieldState: { invalid, isTouched, isDirty },
    formState: { touchedFields, dirtyFields }
  } = useController({
    name,
    control,
    rules: { required: true },
    defaultValue: "",
  });

  return (
    <TextField 
      onChange={onChange} // send value to hook form 
      onBlur={onBlur} // notify when input is touched/blur
      value={value} // input value
      name={name} // send down the input name
      inputRef={ref} // send input ref, so we can focus on input when error appear
    />
  );
}
CodeSandbox 
import * as React from "react";
import { useController, useForm } from "react-hook-form";

const Checkboxes = ({ options, control, name }) => {
  const { field } = useController({
    control,
    name
  });
  const [value, setValue] = React.useState(field.value || []);

  return (
    <>
      {options.map((option, index) => (
        <input
          onChange={(e) => {
            const valueCopy = [...value];

            // update checkbox value
            valueCopy[index] = e.target.checked ? e.target.value : null;

            // send data to react hook form
            field.onChange(valueCopy);

            // update local state
            setValue(valueCopy);
          }}
          key={option}
          checked={value.includes(option)}
          type="checkbox"
          value={option}
        />
      ))}
    </>
  );
};

export default function App() {
  const { register, handleSubmit, control } = useForm({
    defaultValues: {
      controlled: [],
      uncontrolled: []
    }
  });
  const onSubmit = (data) => console.log(data);

  return (
    <form onSubmit={handleSubmit(onSubmit)}>
      <section>
        <h2>uncontrolled</h2>
        <input {...register("uncontrolled")} type="checkbox" value="A" />
        <input {...register("uncontrolled")} type="checkbox" value="B" />
        <input {...register("uncontrolled")} type="checkbox" value="C" />
      </section>

      <section>
        <h2>controlled</h2>
        <Checkboxes
          options={["a", "b", "c"]}
          control={control}
          name="controlled"
        />
      </section>
      <input type="submit" />
    </form>
  );
}

Tips

  • Do not register input again. This custom hook is designed to take care of the registration process.

    const { field } = useController({ name: 'test' })

<input {...field} /> // ✅
<input {...field} {...register('test')} /> // ❌ double up the registration

  • It's ideal to use a single useController per component. If you need to use more than one, make sure you rename the prop. May want to consider using Controller instead.

    const { field: input } = useController({ name: 'test' })
const { field: checkbox } = useController({ name: 'test1' })

<input {...input} />
<input {...checkbox} />

Thank you for your support

If you find React Hook Form to be useful in your project, please consider to star and support it.

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