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The useField composable creates and manages an individual form field in Vue applications.

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Import

import { useField } from '@tanstack/vue-form'

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Signature

function useField<
  TParentData,
  TName extends DeepKeys<TParentData>,
  TData extends DeepValue<TParentData, TName>,
  // ... additional type parameters
>(
  opts: UseFieldOptions<TParentData, TName, TData, ...>
): {
  api: FieldApi<TParentData, TName, TData, ...> & VueFieldApi<...>
  state: Readonly<Ref<FieldState<TData>>>
}

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Parameters

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opts
UseFieldOptions<TParentData, TName, TData>
required
Configuration object for the field.
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opts.form
FormApi<TParentData>
required
The parent form API instance.
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opts.name
TName
required
The field name as a path string (e.g., ‘user.firstName’ or ‘items[0].name’).
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opts.defaultValue
TData
The default value for the field.
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opts.validators
FieldValidators<TParentData, TName, TData>
Validation functions for the field.
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opts.validators.onChange
FieldValidateOrFn<TParentData, TName, TData>
Validator that runs on every change.
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opts.validators.onChangeAsync
FieldAsyncValidateOrFn<TParentData, TName, TData>
Async validator that runs on change.
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opts.validators.onBlur
FieldValidateOrFn<TParentData, TName, TData>
Validator that runs when the field loses focus.
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opts.validators.onMount
FieldValidateOrFn<TParentData, TName, TData>
Validator that runs when the field is mounted.
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opts.asyncDebounceMs
number
Debounce time in milliseconds for async validation. Default is 500ms.
​
opts.asyncAlways
boolean
If true, async validation runs even if sync validation fails.

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Return Value

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api
FieldApi<TParentData, TName, TData> & VueFieldApi
The field API instance.
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name
TName
The field name.
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state
FieldState<TData>
The current field state including value, errors, and metadata.
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handleChange
(value: TData) => void
Update the field value.
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handleBlur
() => void
Mark the field as touched.
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pushValue
(value: TData extends Array<infer U> ? U : never) => void
Add a value to an array field.
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removeValue
(index: number) => void
Remove a value from an array field.
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Field
FieldComponent
A nested Field component for creating sub-fields.
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state
Readonly<Ref<FieldState<TData>>>
A reactive reference to the field state.
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state.value
TData
The current field value.
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state.meta
FieldMeta
Field metadata.
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state.meta.errors
string[]
Current validation errors.
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state.meta.isTouched
boolean
Whether the field has been touched.
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state.meta.isDirty
boolean
Whether the field value has changed.
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state.meta.isValidating
boolean
Whether async validation is in progress.

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Usage Example

<script setup lang="ts">
import { useForm } from '@tanstack/vue-form'

interface FormData {
  email: string
}

const form = useForm<FormData>({
  defaultValues: {
    email: '',
  },
  onSubmit: async ({ value }) => {
    console.log('Email:', value.email)
  },
})

const emailField = form.useField({
  name: 'email',
  validators: {
    onChange: ({ value }) => {
      const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
      return !emailRegex.test(value) ? 'Invalid email address' : undefined
    },
  },
})
</script>

<template>
  <div>
    <label :htmlFor="emailField.api.name">Email:</label>
    <input
      :id="emailField.api.name"
      :name="emailField.api.name"
      :value="emailField.api.state.value"
      @input="(e) => emailField.api.handleChange((e.target as HTMLInputElement).value)"
      @blur="emailField.api.handleBlur"
    />
    <div v-if="emailField.state.value.meta.isTouched && emailField.state.value.meta.errors.length">
      <span style="color: red">{{ emailField.state.value.meta.errors[0] }}</span>
    </div>
  </div>
</template>

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See Also