Forms

Redwood provides several helpers to make building forms easier. All of Redwood's helpers are simple wrappers around React Hook Form (RHF) that make it even easier to use in most cases.

If Redwood's helpers aren't flexible enough for you, you can use React Hook Form directly. @redwoodjs/forms exports everything it does:

import {
  useForm,
  useFormContext,
  /**
   * Or anything else React Hook Form exports!
   *
   * @see {@link https://react-hook-form.com/api}
   */
} from '@redwoodjs/forms'

Overview

@redwoodjs/forms exports the following components:

Component	Description
<Form>	Surrounds all components, providing form and error contexts
<FormError>	Displays error messages from the server. Typically placed at the top of your form
<Label>	Used in place of the HTML <label> tag. Accepts error-styling props
<InputField>	Used in place of the HTML <input> tag. Accepts validation and error-styling props (also see the list of input field components enumerated below)
<SelectField>	Used in place of the HTML <select> tag. Accepts validation and error-styling props
<TextAreaField>	Used in place of the HTML <textarea> tag. Accepts validation and error-styling props
<FieldError>	Displays error messages if the field with the same name prop has validation errors. Only renders if there's an error on the associated field
<Submit>	Used in place of <button type="submit">. Triggers validation and "submission" (executes the function passed to <Form>'s onSubmit prop)

All HTML <input> types are also available as components. They follow the naming convention <TypeField> where Type is one of the HTML input types. We'll refer to them collectively as "input fields". The full list is:

• <ButtonField>
• <CheckboxField>
• <ColorField>
• <DateField>
• <DatetimeLocalField>
• <EmailField>
• <FileField>
• <HiddenField>
• <ImageField>
• <MonthField>
• <NumberField>
• <PasswordField>
• <RadioField>
• <RangeField>
• <ResetField>
• <SearchField>
• <SubmitField>
• <TelField>
• <TextField>
• <TimeField>
• <UrlField>
• <WeekField>

Validation and Error-styling Props

All components ending in Field (i.e. all input fields, along with <SelectField> and <TextAreaField>) accept validation and error-styling props. By validation and error-styling props, we mean three props specifically:

• validation, which accepts all of React Hook Form's register options, plus the Redwood-exclusive coercion helpers valueAsBoolean, valueAsJSON
• errorClassName and errorStyle, which are the classes and styles to apply if there's an error

Besides name, all other props passed to these components are forwarded to the tag they render. Here's a table for reference:

Prop	Description
name	The name of the field. React Hook Form uses it a key to hook it up with everything else
validation	All your validation logic. Accepts all of React Hook Form's register options, plus the Redwood-exclusive coercion helpers valueAsBoolean, valueAsJSON
errorClassName	The class name to apply if there's an error
errorStyle	The style to apply if there's an error

Example

A typical React component using these helpers would look something like this:

import {
  Form,
  Label,
  TextField,
  TextAreaField,
  FieldError,
  Submit,
} from '@redwoodjs/forms'

const ContactPage = () => {
  const onSubmit = (data) => {
    console.log(data)
  }

  return (
    <Form onSubmit={onSubmit}>
      <Label name="name" className="label" errorClassName="label error" />
      <TextField
        name="name"
        className="input"
        errorClassName="input error"
        validation={{ required: true }}
      />
      <FieldError name="name" className="error-message" />

      <Label name="email" className="label" errorClassName="label error" />
      <TextField
        name="email"
        className="input"
        errorClassName="input error"
        validation={{
          required: true,
          pattern: {
            value: /[^@]+@[^\.]+\..+/,
          },
        }}
      />
      <FieldError name="email" className="error-message" />

      <Label name="message" className="label" errorClassName="label error" />
      <TextAreaField
        name="message"
        className="input"
        errorClassName="input error"
        validation={{ required: true }}
      />
      <FieldError name="message" className="error-message" />

      <Submit className="button">Save</Submit>
    </Form>
  )
}

<Form>

Any form you want Redwood to validate and style in the presence errors should be surrounded by this tag.

Prop	Description
config	Accepts an object containing options for React Hook Form's useForm hook
formMethods	The functions returned from useForm. You only need to use this prop if you need to access to one of the functions that useForm returns (see example below)
onSubmit	Accepts a function to be called if validation succeeds. Called with an object containing name-value pairs of all the fields in your form

All other props are forwarded to the <form> tag that it renders.

<Form> Explained

<Form> encapsulates React Hook Form's useForm hook and <FormProvider> context, along with Redwood's ServerError context. It's hard to talk about this component without getting into the nitty-gritty of React Hook Forms.

useForm is React Hook Form's major hook. It returns a bunch of functions, one of which is register, which you use to quite literally "register" fields into React Hook Form so it can validate them. (This has to do with controlled vs. uncontrolled components. React Hook Form takes the latter approach.)

All of Redwood's form helpers need the register function to do what they do. But they don't get it straight from <Form> because they could be nested arbitrarily deep. That's where <FormProvider> comes in: by passing the functions returned from useForm to <FormProvider>, Redwood's helpers can just use useFormContext to get what they need.

Using formMethods

There's some functions that useForm returns that it'd be nice to have access to. For example, useForm returns a function reset, which resets the form's fields. To access it, you have to call useForm yourself. But you still need to pass useForm's return to the <FormProvider> so that Redwood's helpers can register themselves:

import { useForm } from 'react-hook-form'

const ContactPage = () => {
  const formMethods = useForm()

  const onSubmit = (data) => {
    console.log(data)
    formMethods.reset()
  }

  return (
    <Form formMethods={formMethods} onSubmit={onSubmit}>
      // Still works!
      <TextField name="name" validation={{ required: true }}>
    </Form>
  )
}

<FormError>

This helper renders a <div> containing a "title" message and a <ul> enumerating any errors reported by the server when trying to save your form. You can see it in a scaffold if you submit a form that somehow gets passed client-side validation:

For example, let's say you have a form with a <TextField> for a user's email address, but you didn't specify any validation on it:

import { useMutation } from '@redwoodjs/web'

const CREATE_CONTACT = gql`
  mutation CreateContactMutation($input: ContactInput!) {
    createContact(input: $input) {
      id
    }
  }
`

const ContactPage = () => {
  const [create, { loading, error }] = useMutation(CREATE_CONTACT)

  const onSubmit = (data) => {
    create({ variables: { input: data }})
  }

  return (
    <Form onSubmit={onSubmit}>
      <FormError error={error}>
      // No validation—any email goes!
      <TextField name="email" />
    </Form>
  )
}

Since there's no validation, anything goes! On the client at least. GraphQL is built on types, so it's not going to let just anything through. Instead it'll throw an error and bubble it back up to the top (via the error object returned by the useMutation hook) where <FormError> can render something like:

<div>
  <p>
    Can't create new contact:
  </p>
  <ul>
    <li>
      email is not formatted like an email address
    </li>
  </ul>
</div>

<Label>

Renders an HTML <label> tag with different className and style props depending on whether the field it's associated with has a validation error.

This tag can be self-closing, in which case the name becomes the text of the label:

<Label name="name" className="input" errorClassName="input error" />

<!-- Renders: <label for="name" class="input">name</label> -->

It can also have standard separate open/close tags and take text inside, in which case that text is the text of the rendered <label>:

<Label name="name" className="input" errorClassName="input error">Your Name</Label>

<!-- Renders: <label for="name" class="input">Your Name</label> -->

All props are passed to the underlying <label> tag besides the ones listed below:

Prop	Description
name	The name of the field that this label is associated with. This should be the same as the name prop on the input field this label is for
errorClassName	The className that's used if the field with the same name has a validation error
errorStyle	The style that's used if the field with the same name has a validation error

Input Fields

Inputs are the backbone of most forms. While you can use <InputField> and it's type prop to make all the different kinds of input fields you'd use in a form, it's often easier to reach for the named input fields (listed above) which have defaults for things like coercion configured where appropriate.

Default coercion

Certain input fields handle coercion automatically, but you can always override the coercion or, if it's not built-in, set it manually via the validation prop's setValueAs property.

The input fields that coerce automatically are:

Field	Default coercion
<CheckboxField>	valueAsBoolean
<NumberField>	valueAsNumber
<DateField>	valueAsDate
<DatetimeLocalField>	valueAsDate

valueAsDate and valueAsNumber are built into React Hook Form and are based on the HTML standard. But because Redwood uses GraphQL on the backend, it's important that the types submitted by the form be what the GraphQL server expects. Instead of forcing users to make heavy-use of setValueAs for custom coercion, Redwood extends react hook form's valueAs properties with two more for convenience:

• valueAsBoolean
• valueAsJSON

Default treatment of empty input values

Redwood provides a flexible treatment of empty input field value. Appropriate treatment of empty fields can make working with fields for database relations easier.

The treatment of empty field values is governed by the following:

1. If setValueAs is specified by the user, the specified function will determine the behavior of empty fields.
2. If the emptyAs prop is set, then the emptyAs prop will determine the field value on an empty condition. See below for emptyAs prop values.
3. If the validation = { required: true } prop is set, an empty field will return null. However, the validation provided by react-hook-forms should engage and prevent submission of the form as an empty value would not satisfy the required validation.
4. If the field is an Id field, that is its name ends in "Id", then an empty field will return null. A null value is the most appropriate value for most database relation fields. For scenarios where another value is required for empty cases, utilize the emptyAs prop.
5. If none of the above cases apply, the field value will be set as follows for empty field scenarios:
   • DateFields → null
   • NumberFields → NaN
   • TextFields with valueAsNumber set → NaN
   • SelectFields with valueAsNumber set → NaN
   • SelectFields without valueAsNumber set → '' (empty string)
   • TextFields with valueAsJSON set → null
   • TextFields and comparable → '' (empty string)

emptyAs prop

The emptyAs prop allows the user to override the default value for an input field if the field is empty. Provided that a setValueAs prop is not specified, Redwood will allow you to override the default empty value returned. The possible values for emptyAs are:

• null
• 'undefined'
• 0
• '' (empty string)

For example:

<NumberField name="quantity" emptyAs="undefined" />
<NumberField name="score" emptyAs={null} />

will return undefined if the field is empty.

Custom Input Fields

You can create a custom field that integrates with Redwood through the use of Redwood's useRegister and useErrorStyles hooks. Each of these serving a different purpose depending on what you are trying to build.

useRegister registers the field with react-hook-form and is a wrapper for register.

useErrorStyles sets up error styling for your custom input field.

Using these two together you can create custom input fields that replicate a Redwood input field while also allowing for custom domain logic.

In the following example we have an all-in-one custom required input field with label, input, and error display.

import { FieldError, useErrorStyles, useRegister } from '@redwoodjs/forms'

const RequiredField = ({ label, name, validation }) => {
  const register = useRegister({
    name,
    validation: {...validation, required: true}
  })

  const { className: labelClassName, style: labelStyle } = useErrorStyles({
    className: `my-label-class`,
    errorClassName: `my-label-error-class`,
    name,
  })

  const { className: inputClassName, style: inputStyle } = useErrorStyles({
    className: `my-input-class`,
    errorClassName: `my-input-error-class`,
    name,
  })

  return (
    <>
      <label className={labelClassName} style={labelStyle}>{label}</label>
      <input
        className={inputClassName}
        style={inputStyle}
        type="text"
        {...register}
      />
      <FieldError name={name}>
    </>
  )
}

<SelectField>

Renders an HTML <select> tag. It's possible to select multiple values using the multiple prop. When multiple is true, this field returns an array of values in the same order as the list of options, not in the order they were selected.

<SelectField name="toppings" multiple={true}>
  <option>'lettuce'</option>
  <option>'tomato'</option>
  <option>'pickle'</option>
  <option>'cheese'</option>
</SelectField>

// If the user chooses lettuce, tomato, and cheese,
// the onSubmit handler receives:
//
// { toppings: ["lettuce", "tomato", "cheese"] }
//

Validation

In these two examples, one with multiple-field selection, validation requires that a field be selected and that the user doesn't select the first value in the dropdown menu:

<SelectField
  name="selectSingle"
  validation={{
    required: true,
    validate: {
      matchesInitialValue: (value) => {
        return (
          value !== 'Please select an option' ||
          'Select an Option'
        )
      },
    },
  }}
>
  <option>Please select an option</option>
  <option>Option 1</option>
  <option>Option 2</option>
</SelectField>
<FieldError name="selectSingle" style={{ color: 'red' }} />

<SelectField
  multiple={true}
  name="selectMultiple"
  validation={{
    required: true,
    validate: {
      matchesInitialValue: (value) => {
        let returnValue = [true]
        returnValue = value.map((element) => {
          if (element === 'Please select an option')
            return 'Select an Option'
        })
        return returnValue[0]
      },
    },
  }}
>
  <option>Please select an option</option>
  <option>Option 1</option>
  <option>Option 2</option>
</SelectField>
<FieldError name="selectMultiple" style={{ color: 'red' }} />

Coercion

Typically, a <SelectField> returns a string, but you can use one of the valueAs properties to return another type. An example use-case is when <SelectField> is being used to select a numeric identifier. Without the valueAsNumber property, <SelectField> returns a string. But, as per the example below, the valueAsNumber can be used to return an Int:

<SelectField name="select" validation={{ valueAsNumber: true }}>
  <option value={1}>Option 1</option>
  <option value={2}>Option 2</option>
  <option value={3}>Option 3</option>
</SelectField>

If Option 3 is selected, the <Form>'s onSubmit function is passed data as follows:

{
  select: 3,
}

<FieldError>

Renders a <span> containing a validation error message if the field with the same name attribute has a validation error. Otherwise renders nothing.

<FieldError name="name" className="error-message">

<!-- Renders: <span class="error-message">name is required</span> -->