use-form

Manage form state
Import

Installation

@mantine/form package does not depend on any other libraries, you can use it with or without @mantine/core inputs:

Install with npm:

npm install @mantine/form

Install with yarn:

yarn add @mantine/form

Usage

import { TextInput, Checkbox, Button, Group, Box } from '@mantine/core';
import { useForm } from '@mantine/form';
function Demo() {
const form = useForm({
initialValues: {
email: '',
termsOfService: false,
},
validate: {
email: (value) => (/^\S+@\S+$/.test(value) ? null : 'Invalid email'),
},
});
return (
<Box sx={{ maxWidth: 300 }} mx="auto">
<form onSubmit={form.onSubmit((values) => console.log(values))}>
<TextInput
withAsterisk
label="Email"
placeholder="your@email.com"
{...form.getInputProps('email')}
/>
<Checkbox
mt="md"
label="I agree to sell my privacy"
{...form.getInputProps('termsOfService', { type: 'checkbox' })}
/>
<Group position="right" mt="md">
<Button type="submit">Submit</Button>
</Group>
</form>
</Box>
);
}

API overview

All examples below use the following example use-form hook.

import { useForm } from '@mantine/form';
const form = useForm({
initialValues: {
path: '',
path2: '',
user: {
firstName: 'John',
lastName: 'Doe',
},
fruits: [
{ name: 'Banana', available: true },
{ name: 'Orange', available: false },
],
accepted: false,
},
});

Values

Form values guide

// get current form values
form.values;
// Set all form values
form.setValues(values);
// Set all form values using the previous state
form.setValues((prev) => ({ ...prev, ...values }));
// Set value of single field
form.setFieldValue('path', value);
// Set value of nested field
form.setFieldValue('user.firstName', 'Jane');
// Resets form.values to initialValues,
// clears all validation errors,
// resets touched and dirty state
form.reset();

List items

Nested fields guide

// Inserts given list item at the specified path
form.insertListItem('fruits', { name: 'Apple', available: true });
// An optional index may be provided to specify the position in a nested field.
// If the index is passed where an item already exists, it will be replaced.
// If the index is larger than the current list, the element is inserted at the last position.
form.insertListItem('fruits', { name: 'Orange', available: true }, 1);
// Removes the list item at the specified path and index.
form.removeListItem('fruits', 1);
// Swaps two items of the list at the specified path.
// If no element exists at the `from` or `to` index, the list doesn't change.
form.reorderListItem('fruits', { from: 1, to: 0 });

Validation

Form validation guide

import { useForm } from '@mantine/form';
const form = useForm({
initialValues: {
email: '',
user: {
firstName: '',
lastName: '',
},
},
validate: {
email: (value) => (value.length < 2 ? 'Invalid email' : null),
user: {
firstName: (value) => (value.length < 2 ? 'First name must have at least 2 letters' : null),
},
},
});
// Validates all fields with specified `validate` function or schema, sets form.errors
form.validate();
// Validates single field at specified path, sets form.errors
form.validateField('user.firstName');
// Works the same way as form.validate but does not set form.errors
form.isValid();
form.isValid('user.firstName');

Errors

Form errors guide

Validation errors occur when defined validation rules were violated, initialErrors were specified in useForm properties or validation errors were set manually.

// get current errors state
form.errors;
// Set all errors
form.setErrors({ path: 'Error message', path2: 'Another error' });
// Set error message at specified path
form.setFieldError('user.lastName', 'No special characters allowed');
// Clears all errors
form.clearErrors();
// Clears error of field at specified path
form.clearFieldError('path');

onReset and onSubmit

Wrapper function for form onSubmit and onReset event handler. onSubmit handler accepts as second argument a function that will be called with errors object when validation fails.

<form onSubmit={form.onSubmit(setFormValues)}></form>
<form onSubmit={form.onSubmit(
(values, _event) => { setFormValues(values) },
(validationErrors, _values, _event) => { console.log(validationErrors) }
)}></form>
<form onReset={form.onReset}></form>

Touched and dirty

Touched & dirty guide

// Returns true if user interacted with any field inside form in any way
form.isTouched();
// Returns true if user interacted with field at specified path
form.isTouched('path');
// Set all touched values
form.setTouched({ 'user.firstName': true, 'user.lastName': false });
// Clears touched status of all fields
form.resetTouched();
// Returns true if form values are not deep equal to initialValues
form.isDirty();
// Returns true if field value is not deep equal to initialValues
form.isDirty('path');
// Sets dirty status of all fields
form.setDirty({ 'user.firstName': true, 'user.lastName': false });
// Clears dirty status of all fields, saves form.values snapshot
// After form.resetDirty is called, form.isDirty will compare
// form.values to snapshot instead of initialValues
form.resetDirty();

getInputProps

form.getInputProps returns an object with value, onChange, onFocus, onBlur and error that should be spread on input.

As second parameter options can be passed.

  • type: default input. Needs to be configured to checkbox if input requires checked to be set instead of value.
  • withError: default type === 'input'. Specifies if the returned object contains an error property with form.errors[path] value.
  • withFocus: default true. Specifies if the returned object contains an onFocus handler. If disabled, the touched state of the form can only be used if all values are set with setFieldValue.
<TextInput {...form.getInputProps('path')} />
<Checkbox {...form.getInputProps('accepted', { type: 'checkbox' })} />

UseFormReturnType

UseFormReturnType can be used when you want to pass form as a prop to another component:

import { TextInput } from '@mantine/core';
import { useForm, UseFormReturnType } from '@mantine/form';
interface FormValues {
name: string;
occupation: string;
}
function NameInput({ form }: { form: UseFormReturnType<FormValues> }) {
return <TextInput {...form.getInputProps('name')} />;
}
function OccupationInput({ form }: { form: UseFormReturnType<FormValues> }) {
return <TextInput {...form.getInputProps('occupation')} />;
}
function Demo() {
const form = useForm<FormValues>({ initialValues: { name: '', occupation: '' } });
return (
<>
<NameInput form={form} />
<OccupationInput form={form} />
</>
);
}