Forms in OpnForm handle both client-side validation and server-side API integration. They work seamlessly with TanStack Query mutations for optimal user experience.

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Form System Overview

Our form system consists of three main parts:
  1. Form Class (client/composables/lib/vForm/Form.js) - Core form state management
  2. useFormInput Composable (client/components/forms/useFormInput.js) - Input component logic
  3. Form Components (client/components/forms/) - Reusable input components

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Creating a Basic Form

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1. Initialize the Form

<script setup>
const form = useForm({
  email: '',
  password: '',
  remember: false
})
</script>
The useForm composable creates a reactive form instance with:
  • Data binding - automatic two-way data binding
  • Validation state - tracks errors and validation status
  • Loading state - busy/successful flags for UI feedback
  • Error handling - automatic error extraction from API responses

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2. Create the Form Template

<template>
  <form @submit.prevent="handleSubmit">
    <TextInput
      name="email"
      :form="form"
      label="Email"
      :required="true"
      placeholder="Your email address"
    />
    
    <TextInput
      native-type="password"
      name="password"
      :form="form"
      label="Password"
      :required="true"
      placeholder="Your password"
    />
    
    <CheckboxInput
      :form="form"
      name="remember"
      label="Remember me"
    />
    
    <UButton
      type="submit"
      :loading="form.busy"
      :disabled="form.busy"
      label="Submit"
    />
  </form>
</template>

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3. Handle Form Submission

<script setup>
const { login } = useAuth()
const loginMutation = login()

const handleSubmit = () => {
  // Using TanStack Query mutation
  form.mutate(loginMutation)
    .then(() => {
      useAlert().success('Login successful!')
      // Handle success
    })
    .catch((error) => {
      // Errors are automatically handled by the form
      console.log('Login failed:', error)
    })
}
</script>

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Form Input Components

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Using Form Inputs

All form inputs accept a common set of props through the useFormInput composable: 
<TextInput
  name="email"           <!-- Required: field name -->
  :form="form"           <!-- Required: form instance -->
  label="Email Address"  <!-- Optional: field label -->
  :required="true"       <!-- Optional: required validation -->
  placeholder="Enter your email"
  help="We'll never share your email"
  :disabled="form.busy"
/>

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Available Input Components

  • <TextInput> - Text, email, password, etc.
  • <TextareaInput> - Multi-line text
  • <CheckboxInput> - Checkboxes
  • <SelectInput> - Dropdown selects
  • … and more!

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Custom Input Components

Create custom inputs using the useFormInput composable: 
<script setup>
import { useFormInput, inputProps } from '@/components/forms/useFormInput.js'

const props = defineProps({
  ...inputProps,
  // Add custom props here
})

const emit = defineEmits(['update:modelValue'])

const { compVal, hasError, hasValidation } = useFormInput(props, { emit })
</script>

<template>
  <div>
    <label>{{ props.label }}</label>
    <input
      v-model="compVal"
      :class="{ 'error': hasError }"
      :disabled="props.disabled"
    />
    <span v-if="hasError" class="error-message">
      {{ props.form.errors.get(props.name) }}
    </span>
  </div>
</template>

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Validation & Error Handling

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Client-Side Validation

Form validation happens automatically: 
<TextInput
  name="email"
  :form="form"
  :required="true"
  type="email"
/>

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Server-Side Validation

The form automatically handles API validation errors: 
// API returns validation errors like:
{
  "errors": {
    "email": ["The email field is required."],
    "password": ["The password must be at least 8 characters."]
  }
}

// Form automatically displays these errors on the respective inputs

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Precognition (Live Validation)

Use real-time server validation as users type with Laravel Precognition. 
<script setup>
const form = useForm({ email: '', password: '' })

const validateField = (fieldName) => {
  form.validate('post', '/api/auth/login', {}, new Set([fieldName]))
}
</script>

<template>
  <TextInput
    name="email"
    :form="form"
    @blur="validateField('email')"
  />
</template>

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Error States

Access validation state programmatically: 
<script setup>
const form = useForm({ email: '' })

// Check if form has any errors
const hasErrors = computed(() => form.errors.any())

// Check specific field errors
const emailError = computed(() => form.errors.get('email'))

// Form state
const isSubmitting = computed(() => form.busy)
const wasSuccessful = computed(() => form.successful)
</script>

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Integration with TanStack Query

Forms integrate seamlessly with TanStack Query mutations for optimal caching and state management: 
<script setup>
const { create } = useWorkspaces()
const createMutation = create()

const form = useForm({
  name: '',
  description: ''
})

const handleSubmit = () => {
  form.mutate(createMutation)
    .then((newWorkspace) => {
      // Cache is automatically updated by the mutation
      useAlert().success('Workspace created!')
      router.push(`/workspaces/${newWorkspace.id}`)
    })
    .catch((error) => {
      // Form errors are automatically handled
      useAlert().error('Failed to create workspace')
    })
}
</script>
See Data Fetching for more details on how mutations work with caching and optimistic updates.

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Form State Management

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Form Methods

const form = useForm({ name: 'John', email: 'john@example.com' })

// Get form data
const data = form.data() // { name: 'John', email: 'john@example.com' }

// Reset form to original state
form.reset()

// Clear form and set new data
form.resetAndFill({ name: 'Jane', email: 'jane@example.com' })

// Clear errors and state
form.clear()

// Fill form with partial data
form.fill({ name: 'Updated Name' })

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Form State Properties

// Loading state
form.busy           // Currently submitting
form.successful     // Last submission was successful
form.recentlySuccessful // Recently successful (with timeout)

// Error state
form.errors.any()   // Has any errors
form.errors.get('field') // Get specific field error
form.errors.has('field') // Check if field has error

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Complete Example

Here’s a complete working example based on the LoginForm component: 
<template>
  <form @submit.prevent="handleLogin">
    <TextInput
      name="email"
      :form="form"
      label="Email"
      :required="true"
      placeholder="Your email address"
    />
    
    <TextInput
      native-type="password"
      name="password"
      :form="form"
      label="Password"
      :required="true"
      placeholder="Your password"
    />
    
    <CheckboxInput
      :form="form"
      name="remember"
      label="Remember me"
    />
    
    <UButton
      type="submit"
      :loading="form.busy"
      :disabled="form.busy"
      label="Log in to continue"
    />
  </form>
</template>

<script setup>
const { login } = useAuth()
const loginMutation = login()

const form = useForm({
  email: '',
  password: '',
  remember: false
})

const handleLogin = () => {
  form.mutate(loginMutation)
    .then(() => {
      useAlert().success('Login successful!')
      // Handle redirect
    })
    .catch((error) => {
      if (error.response?.status === 422) {
        // Validation errors are automatically handled
        useAlert().error('Please check your credentials')
      } else {
        useAlert().error('Login failed. Please try again.')
      }
    })
}
</script>

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Best Practices

Form State Management: Always use the useForm composable rather than managing form state manually. It handles validation, errors, and loading states automatically.
Error Handling: Let the form handle API validation errors automatically. Only add custom error handling for specific business logic.
File Uploads: When handling file uploads, the form will automatically serialize data as FormData. Make sure your API endpoint accepts multipart/form-data.
Validation: Combine client-side validation (required, email, etc.) with server-side validation for the best user experience.