Types

FieldProps


FieldProps

These are props that you pass to <Field/>. You must provide one of the ways to render: component, render, or children.

afterSubmit

() => void

Optional.

A callback to notify fields after submission has completed successfully.

allowNull

boolean

Optional. Defaults to false.

By default, if your value is null, <Field/> will convert it to '', to ensure controlled inputs.

But if you pass true to allowNull, <Field/> will give you a null value.

beforeSubmit

() => void | false

Optional.

A function to call just before calling onSubmit. If beforeSubmit returns false, the submission will be aborted. If one of your fields returns false on beforeSubmit, other fields may not have their beforeSubmit called, as the submission is aborted on the first one that returns false.

children

((props: FieldRenderProps) => React.Node) | React.Node`

Optional. (if you specify component or render)

A render function that is given FieldRenderProps, as well as any non-API props passed into the <Field/> component. For example, if you did...

<Field name="myField" someArbitraryOtherProp={42}>
  {props => {
    console.log(props.someArbitraryOtherProp) // would print 42
    return <input {...props.input}/>
  }}
</Form>

Note that if you specify render or component and children, render will be called, with children injected as if it were an additional prop. This can be especially useful for doing something like:

<Field name="favoriteColor" component="select">
  <option value="FF0000">Red</option>
  <option value="00FF00">Green</option>
  <option value="0000FF">Blue</option>
</Field>

Related:

component

React.ComponentType<FieldRenderProps> | 'input' | 'select' | 'textarea'`

Optional. If you are not using 'input', 'select' or 'textarea', it is recommended that you use children or render.

Either the string name of one of the default HTML inputs, or a component that is given FieldRenderProps as props, children and render props, as well as any non-API props passed into the <Field/> component. For example, if you did...

<Field
  name="myField"
  someArbitraryOtherProp={42}
  component={MyFieldComp} />

const MyFieldComp = props => {
  console.log(props.someArbitraryOtherProp) // would print 42
  return <input {...props.input} />
}

Related:

data

Object

Optional.

Initial state for arbitrary values to be placed by mutators.

defaultValue

any

Optional. ⚠️ You probably want initialValue! ⚠️

The value of the field upon creation. This value is only needed if you want your field be dirty upon creation (i.e. for its value to be different from its initial value).

format

(value: any, name: string) => any

Optional.

A function that takes the value from the form values and the name of the field and formats the value to give to the input. Common use cases include converting javascript Date values into a localized date string. Almost always used in conjunction with parse.

Note: If you would like to disable the default behavior of converting undefined to '', you can pass an identity function, v => v, to format. If you do this, making sure your inputs are "controlled" is up to you.

formatOnBlur

boolean

Optional. Defaults to false.

If true, the format function will only be called when the field is blurred. If false, format will be called on every render.

initialValue

any

Optional.

The initial value for the field. This value will be used to calculate dirty and pristine by comparing it to the current value of the field. If you want field to be dirty upon creation, you can set one value with initialValue and set the value of the field with defaultValue.

The value given here will override any initialValues given to the entire form.

isEqual

(a: any, b: any) => boolean

Optional. Defaults to ===.

A function to determine if two values are equal.

name

string

Required

The name of your field. Field values may be deeply nested using dot-and-bracket syntax.

Learn more about Field Names.

parse

(value: any, name: string) => any

Optional.

A function that takes the value from the input and name of the field and converts the value into the value you want stored as this field's value in the form. Common usecases include converting strings into Numbers or parsing localized dates into actual javascript Date objects. Almost always used in conjuction with format.

Note: If would like to override the default behavior of converting '' to undefined, you can pass an identity function, v => v, to parse, thus allowing you to have form values of ''.

render

(props: FieldRenderProps) => React.Node

Optional. (if you specify component or children)

A render function that is given FieldRenderProps, as well as any non-API props passed into the <Field/> component. For example, if you did...

<Field
  name="myField"
  someArbitraryOtherProp={42}
  render={props => {
    console.log(props.someArbitraryOtherProp) // would print 42
    return <input {...props.input} />
  }}
/>

Note that if you specify render and children, render will be called, with children injected as if it were an additional prop.

Related:

subscription

{ [string]: boolean }

Optional. Advanced Usage

An object of the parts of FieldState to subscribe to. If a subscription is provided, the <Field/> will only rerender when those parts of field state change.

If no subscription is provided, it will default to subscribing to all field state changes. i.e. <Field/> will rerender whenever any part of the field state changes.

Related:

validate

(value: ?any, allValues: Object, meta: ?FieldState) => ?any

Optional.

A function that takes the field value, all the values of the form and the meta data about the field and returns an error if the value is invalid, or undefined if the value is valid.

⚠️ IMPORTANT ⚠️ – By default, in order to allow inline fat-arrow validation functions, the field will not rerender if you change your validation function to an alternate function that has a different behavior. If you need your field to rerender with a new validation function, you will need to update another prop on the Field, such as key. See the following sandbox for an example:

Edit Changing Field Level Validators

validateFields

string[]

Optional.

An array of field names to validate when this field changes. If undefined, every field will be validated when this one changes; if [], only this field will have its field-level validation function called when it changes; if other field names are specified, those fields and this one will be validated when this field changes.

⚠️ IMPORTANT ⚠️ – By default, in order to allow inline [] syntax, the field will not rerender if you change your validateFields prop changes. If you need your field to rerender with a new validateFields setting, you will need to update another prop on the Field, such as key.

value

any

Optional.

This is only used for checkboxes and radio buttons!

You must also include a type="radio" or type="checkbox" prop.

Radio Buttons

The value of the radio button. The radio button will render as checked if and only if the value given here === the value for the field in the form.

Checkboxes

With value

The checkbox will be checked if the value given in value is contained in the array that is the value for the field for the form. Checking the box will add the value to the array, and unchecking the checkbox will remove the value from the array.

Without value

The checkbox will be checked if the value is truthy. Checking the box will set the value to true, and unchecking the checkbox will set the value to false.