useForm
useForm is a custom composition API function that allows you to group fields created by useField and aggregates their state. It should be used to create logical forms or custom form components similar to the <Form/> component which is just a consumer of useForm.
The most basic usage is where you have both useField and useForm at the same setup function:
import { useField, useForm } from 'vee-validate';
import * as yup from 'yup';
export default {
setup() {
useForm();
const { value: email, errors } = useField('email', yup.string().email().required());
return {
email,
errors,
};
},
};
Field Types
The useForm function has field typing capabilities if you need it, getting type information for your fields and their values can be very powerful when building complex forms.
By unlocking the field type you automatically get more strict information for the various properties/methods exposed by useForm like setErrors and setTouched. There are two ways you can get the advanced typing information for your fields, the first is to provide a generic type to useForm.
import { useForm } from 'vee-validate';
interface LoginForm {
email: string;
password: string;
}
// in your setup
const { errors } = useForm<LoginForm>();
Or simply provide initial values to useForm and it will automatically pick up the type of initialValues and use it for the field types.
import { useForm } from 'vee-validate';
const { errors, setErrors, setFieldValue } = useForm({
initialValues: {
email: '',
password: '',
},
});
Whichever approach you prefer, you get full type information for your fields for all the functions exposed by useForm, here are a few examples.
import { useForm } from 'vee-validate';
interface LoginForm {
email: string;
password: string;
}
// in your setup
const { errors, setErrors, setFieldValue } = useForm<LoginForm>();
errors.value; // typed as { email?: string; password?: string }
setErrors({
email: 'This field is invalid', // auto-complete for `email` and `password`
});
setFieldValue('email', 'example@gmail.com'); // auto-complete for the field name and its value type
For example if you were to do this in the previous example:
setFieldValue('age', 5); // ⛔️ TypeScript error
setFieldValue('email', 5); // ⛔️ TypeScript error
It will error out because age is not defined in the LoginForm type you defined. The second line errors out because the email field is typed as a string.
API Reference
The full signature of the useForm function looks like this:
interface FormOptions {
validationSchema?: any; // A yup schema, or a Record<string, any> containing valid rules as `useField`
initialValues?: Record<string, any>;
initialErrors?: Record<string, string>; // a map of the form's initial error messages
initialDirty?: Record<string, boolean>; // a map of the form's initial dirty fields
initialTouched?: Record<string, boolean>; // a map of the form's initial touched fields
validateOnMount?: boolean;
}
type useForm = (
opts?: FormOptions
) => {
errors: Record<string, string>; // first error message for each field
isSubmitting: boolean; // if the form submission function is being run
submitCount: number; // the number of submission attempts
meta: FormMeta; // aggregate of the field's meta information
values: Record<string, any>; // current form values
setFieldError: (field: string, errorMessage: string) => void; // Sets an error message for a field
setErrors: (fields: Record<string, string>) => void; // Sets error messages for fields
setFieldValue: (field: string, value: any) => void; // Sets a field value
setValues: (fields: Record<string, any>) => void; // Sets multiple fields values
validate: () => Promise<{ errors: Record<string, string>; valid: boolean; }>; // validates the form fields and returns the overall result
validateField: (field: string) => Promise<{ errors: string[]; valid: boolean; }>; // validates the form fields and returns the overall result
handleSubmit: (cb: (values: Record<string, any>, ctx: SubmissionContext)) => () => void; // Creates a submission handler that calls the cb only after successful validation with the form values
submitForm: (e: Event) => void; // Forces submission of a form after successful validation (calls e.target.submit())
handleReset: () => void; // Resets all fields' errors and meta and their values
resetForm: (state?: Partial<FormState>) => void; // Resets all fields' errors and meta and their values to their initial state or the specified state
};
Arguments
validationSchema?: Record<string, string | Function> | Yup.ShapeOf<T>
Enables form-level validation, uses the specified schema to validate the fields. The schema can be either valid vee-validate global validators or functions or a yup object schema.
initialValues?: Record<string, any>
The initial values for the form, can be a reactive object or reference.
const { ... } = useForm({
initialValues: {
email: 'example@gmail.com',
password: 'p@$$w0rd',
}
});
initialErrors?: Record<string, string>
The initial errors for the fields, useful for non hydrated SSR applications like Laravel, errors are applied on mounted.
const { ... } = useForm({
initialErrors: {
email: 'This email is invalid',
password: 'Password too short',
}
});
initialDirty?: Record<string, any>
The initial dirty status for the form fields, applied on mounted.
const { ... } = useForm({
initialDirty: {
email: true, // dirty
password: false, // non-dirty
}
});
initialTouched?: Record<string, any>
The initial touched status for the form fields, applied on mounted.
const { ... } = useForm({
initialTouched: {
email: true, // touched
password: false, // non-touched
}
});
validateOnMount?: boolean
If true, it will trigger validation for all fields once the form component is mounted.
Composable API
The following sections documents each available property on the useForm composable.
errors: Ref<Record<string, string>>
An object that maps field names to their error messages, it only takes the first error message of each field if multiple exists.
const { errors } = useForm();
errors.value; // access the errors value
Here is an example of its shape:
{
email: "this field must be a valid email",
password: "too short"
}
Any fields without error messages will not be included in the object. So you can safety iterate over it with Object.keys() knowing all the included fields are invalid.
isSubmitting: Ref<boolean>
Indicates if the submission handler is still running, once it resolves/rejects it will be automatically set to false again.
const { isSubmitting } = useForm();
isSubmitting.value; // true or false
meta: ComputedRef<FormMeta>
A computed property that contains an aggregated meta information/flags reflecting the state of all the fields inside the form.
interface FormMeta {
touched: boolean; // if at least one field is touched (was blurred)
dirty: boolean; // if at least one field is dirty (manipulated)
valid: boolean; // if the form doesn't have any error messages
pending: boolean; // if at least one field is pending validation
initialValues?: Record<string, any>; // a map of the form's initial values
}
usage
const { meta } = useForm();
meta.value; // { valid: false, invalid: true, dirty: true, .... }
values: Record<string, any>
A computed property that contains the current form values
const { values } = useForm();
values.value; // { email: 'something@gmail.com', .... }
setFieldError: (field: string, message: string | undefined) => void
Sets a field's error message, useful for setting messages form an API or that are not available as a validation rule. Setting the message to undefined or an empty string clears the errors and marks the field as valid.
const { setFieldError } = useForm();
setFieldError('email', 'this email is already taken');
// Mark field as valid
setFieldError('email', undefined);
If you try to set an error for a field that doesn't exist, it will be added to the form's errors object and it will change the form's valid state
setErrors: (fields: Record<string, string | undefined>) => void
Sets multiple fields error messages, uses setFieldError internally.
const { setErrors } = useForm();
setErrors({
email: 'this email is already taken',
password: 'someone already has this password 🤪',
firstName: undefined, // clears errors and marks the field as valid
});
tip
Any missing fields you didn't pass to setErrors will be unaffected and their state will not change
setFieldValue: (field: string, value: any) => void
Sets a field's value, if a field does not exist it will not be reflected in the values ref. This will trigger validation on the field whose value changed.
const { setFieldValue } = useForm();
setFieldValue('email', 'example@gmail.com');
If ou try to set a value for a field that doesn't exist, it will be added to the form's values object and will stay there until the next resetForm is called.
setValues: (fields: Record<string, any>) => void
Sets all fields values, will trigger validation for the changed fields.
const { setValues } = useForm();
setValues({
email: 'example@gmail.com',
password: 'p@a$$W0rD',
});
setFieldTouched: (field: string, isTouched: boolean) => void
Sets a field's touched meta flag, if you set it for a non-existing field it will have no effect.
const { setFieldTouched } = useForm();
setFieldTouched('email', true);
setTouched: (fields: Record<string, boolean>) => void
Sets multiple fields touched meta flag, does not validate.
const { setTouched } = useForm();
setTouched({
email: true,
password: false,
});
validate: () => Promise<{ valid: boolean; errors: Record<string, string>}>
Validates all the fields and populates the errors object, returns a promise that resolves to an object containing aggregated validation result of all fields.
const { validate } = useForm();
const { valid, errors } = await validate();
validateField: (field: string) => Promise<{ valid: boolean; errors: string[] }>
Validates a specific field inside the form, returns a promise that resolves to an object containing the validation result.
const { validateField } = useForm();
const { valid, errors } = await validateField('email');
handleSubmit: (cb: SubmissionHandler) => (evt?: Event) => Promise<void>
This is a higher order function used to create submit event handlers, You shouldn't use it as a handler for the events directly but rather use it to create those handlers.
The handlers created using this function will automatically prevent form submission and stop the propagation of the submit event.
It accepts a function which runs after validating the form and if all fields are valid. The callback you pass will receive the form values as the first argument, which is an object containing the fields' values.
<template>
<form @submit="onSubmit"></form>
</template>
<script>
import { useForm } from 'vee-validate';
export default {
setup() {
const { handleSubmit } = useForm();
// use `onSubmit` as an event handler for your forms
const onSubmit = handleSubmit(values => {
// pretty print the values object
alert(JSON.stringify(values, null, 2));
});
return {
onSubmit,
};
},
};
</script>
For advanced forms, you may need to trigger various actions on the form in the submit handler. Your callback receives a FormActions object as part of the second argument along with the event object that triggered the submission if available.
const { handleSubmit } = useForm();
const onSubmit = handleSubmit((values, actions) => {
// Send data to API
alert(JSON.stringify(values, null, 2));
// the form object contains useful methods
// set a single field value
actions.setFieldValue('field', 'hello');
// set multiple fields values
actions.setValues({ email: 'value', password: 'hi' });
// set a single field error
actions.setFieldError('field', 'this field is bad');
// set multiple fields errors
actions.setErrors({ email: 'bad email', password: 'bad password' });
// reset the form
actions.resetForm();
});
Virtual Forms
You can use handleSubmit to submit virtual forms that may use form elements or not. As you may have noticed the snippet above doesn't really care if you are using forms or not.
submitForm: (evt: Event) => void
Unlike handleSubmit this function can be used as an event handler for form submit event, it will prevent the propagation and submission of the forms using it as long as they are invalid. Once all the fields are valid it will submit the form with the native HTML behavior following the form element's action and method attributes.
This is useful if you plan to handle form submissions using a backend API like Laravel or whatever.
<template>
<form @submit="submitForm" action="/api/login" method="post">
<!-- ... -->
</form>
</template>
<script>
import { useForm } from 'vee-validate';
export default {
setup() {
const { submitForm } = useForm();
return {
submitForm,
};
},
};
</script>
submitCount: number
The number of submission attempts by the user, it increments whenever submitForm or handleSubmit callback are called.
resetForm: (state?: Partial<FormState>) => void
Clears error messages, resets the meta state for all fields and reverts their values to their initial state as well as the submitCount state. Accepts an optional object containing the new form state, useful if you need to reset the form values to different values other than their initial state.
This is the FormState interface:
type TouchedFlags = { [k: string]: boolean };
interface FormState {
// any error messages
errors: Record<string, string>;
// touched meta flags
touched: TouchedFlags;
// Form Values
values: Record<string, any>;
// The form submit attempts count
submitCount: number;
}
In this example, the resetForm function is updating the fields current values to the ones provided, these values will be used as the new initial values for future resetForm or handleReset calls. This also applies if the Field component or useField used their individual resetField function.
const { resetForm } = useForm();
// ...
function onSubmit(values) {
// send values to the API
// ...
// Reset the form values
resetForm({
values: {
firstName: '',
lastName: '',
email: '',
password: '',
},
});
}
handleReset: () => void
Clears error messages, resets the meta state for all fields and reverts their values to their initial state as well as the submitCount state. you can use this function as handler for the reset events on native form elements.
<template>
<form @reset="handleReset">
<!-- ... -->
</form>
</template>
<script>
import { useForm } from 'vee-validate';
export default {
setup() {
const { handleReset } = useForm();
// you can use it in your code
handleReset();
// or pass it to be used in the template
return {
handleReset,
};
},
};
</script>