Formily Migration Guide

This skill provides comprehensive guidance for converting existing React forms to Formily. Focus on migration strategies, common patterns, and step-by-step conversion processes for different form libraries and vanilla React forms with TypeScript.

Migration Overview

Why Migrate to Formily?

1. Better TypeScript support - Type-safe form management
2. Schema-driven approach - Declarative form definitions
3. Improved performance - Efficient reactivity and minimal re-renders
4. Powerful validation - Built-in validation with custom rules
5. Better developer experience - Less boilerplate, more maintainability

Migration Strategies

1. Incremental migration - Convert forms one at a time
2. Parallel development - Build new forms with Formily while maintaining existing ones
3. Complete rewrite - Replace entire form system at once

From Vanilla React Forms

Before: Vanilla React Form

import React, { useState, FormEvent } from 'react'

interface ContactForm {
  name: string
  email: string
  message: string
}

const VanillaContactForm: React.FC = () => {
  const [formData, setFormData] = useState<ContactForm>({
    name: '',
    email: '',
    message: ''
  })

  const [errors, setErrors] = useState<Partial<ContactForm>>({})
  const [isSubmitting, setIsSubmitting] = useState(false)

  const handleChange = (e: React.ChangeEvent<HTMLInputElement | HTMLTextAreaElement>) => {
    const { name, value } = e.target
    setFormData(prev => ({ ...prev, [name]: value }))
    // Clear error when user starts typing
    if (errors[name as keyof ContactForm]) {
      setErrors(prev => ({ ...prev, [name]: '' }))
    }
  }

  const validateForm = (): boolean => {
    const newErrors: Partial<ContactForm> = {}

    if (!formData.name.trim()) {
      newErrors.name = 'Name is required'
    }

    if (!formData.email.trim()) {
      newErrors.email = 'Email is required'
    } else if (!/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(formData.email)) {
      newErrors.email = 'Invalid email format'
    }

    if (!formData.message.trim()) {
      newErrors.message = 'Message is required'
    }

    setErrors(newErrors)
    return Object.keys(newErrors).length === 0
  }

  const handleSubmit = async (e: FormEvent) => {
    e.preventDefault()

    if (!validateForm()) {
      return
    }

    setIsSubmitting(true)

    try {
      // Submit form data
      await submitForm(formData)
      alert('Form submitted successfully!')
      setFormData({ name: '', email: '', message: '' })
    } catch (error) {
      console.error('Submission error:', error)
      alert('Submission failed. Please try again.')
    } finally {
      setIsSubmitting(false)
    }
  }

  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label>Name:</label>
        <input
          type="text"
          name="name"
          value={formData.name}
          onChange={handleChange}
        />
        {errors.name && <span className="error">{errors.name}</span>}
      </div>

      <div>
        <label>Email:</label>
        <input
          type="email"
          name="email"
          value={formData.email}
          onChange={handleChange}
        />
        {errors.email && <span className="error">{errors.email}</span>}
      </div>

      <div>
        <label>Message:</label>
        <textarea
          name="message"
          value={formData.message}
          onChange={handleChange}
        />
        {errors.message && <span className="error">{errors.message}</span>}
      </div>

      <button type="submit" disabled={isSubmitting}>
        {isSubmitting ? 'Submitting...' : 'Submit'}
      </button>
    </form>
  )
}

After: Formily Version

import React from 'react'
import { createForm } from '@formily/core'
import { FormProvider, createSchemaField } from '@formily/react'
import { Form, FormItem, Input, Button } from '@formily/antd'

interface ContactForm {
  name: string
  email: string
  message: string
}

const FormilyContactForm: React.FC = () => {
  const form = createForm<ContactForm>({
    initialValues: {
      name: '',
      email: '',
      message: ''
    },
    validateFirst: true
  })

  const schema = {
    type: 'object',
    properties: {
      name: {
        type: 'string',
        title: 'Name',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input',
        'x-validator': [
          { required: true, message: 'Name is required' }
        ]
      },
      email: {
        type: 'string',
        title: 'Email',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input',
        'x-validator': [
          { required: true, message: 'Email is required' },
          { format: 'email', message: 'Invalid email format' }
        ]
      },
      message: {
        type: 'string',
        title: 'Message',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input.TextArea',
        'x-validator': [
          { required: true, message: 'Message is required' }
        ]
      }
    }
  }

  const SchemaField = createSchemaField({
    components: {
      Form,
      FormItem,
      Input,
      Button
    }
  })

  const handleSubmit = async () => {
    try {
      await form.validate()
      const values = form.values
      await submitForm(values)
      alert('Form submitted successfully!')
      form.reset()
    } catch (error) {
      console.error('Validation errors:', error)
    }
  }

  return (
    <FormProvider form={form}>
      <Form labelCol={6} wrapperCol={16}>
        <SchemaField schema={schema} />
        <FormItem wrapperCol={{ offset: 6, span: 16 }}>
          <Button type="primary" onClick={handleSubmit}>
            Submit
          </Button>
        </FormItem>
      </Form>
    </FormProvider>
  )
}

From Formik

Before: Formik Form

import React from 'react'
import { Formik, Form, Field, ErrorMessage } from 'formik'
import * as Yup from 'yup'

const FormikExample: React.FC = () => {
  const initialValues = {
    firstName: '',
    lastName: '',
    email: '',
    age: ''
  }

  const validationSchema = Yup.object({
    firstName: Yup.string().required('First name is required'),
    lastName: Yup.string().required('Last name is required'),
    email: Yup.string().email('Invalid email').required('Email is required'),
    age: Yup.number().min(18, 'Must be at least 18').required('Age is required')
  })

  const handleSubmit = (values: any, { setSubmitting }: any) => {
    submitForm(values)
    setSubmitting(false)
  }

  return (
    <Formik
      initialValues={initialValues}
      validationSchema={validationSchema}
      onSubmit={handleSubmit}
    >
      {({ isSubmitting }) => (
        <Form>
          <div>
            <label>First Name</label>
            <Field name="firstName" type="text" />
            <ErrorMessage name="firstName" component="div" />
          </div>

          <div>
            <label>Last Name</label>
            <Field name="lastName" type="text" />
            <ErrorMessage name="lastName" component="div" />
          </div>

          <div>
            <label>Email</label>
            <Field name="email" type="email" />
            <ErrorMessage name="email" component="div" />
          </div>

          <div>
            <label>Age</label>
            <Field name="age" type="number" />
            <ErrorMessage name="age" component="div" />
          </div>

          <button type="submit" disabled={isSubmitting}>
            Submit
          </button>
        </Form>
      )}
    </Formik>
  )
}

After: Formily Version

import React from 'react'
import { createForm } from '@formily/core'
import { FormProvider, createSchemaField } from '@formily/react'
import { Form, FormItem, Input, InputNumber, Button } from '@formily/antd'

const FormilyFormikExample: React.FC = () => {
  const form = createForm({
    initialValues: {
      firstName: '',
      lastName: '',
      email: '',
      age: undefined
    }
  })

  const schema = {
    type: 'object',
    properties: {
      firstName: {
        type: 'string',
        title: 'First Name',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input',
        'x-validator': [{ required: true, message: 'First name is required' }]
      },
      lastName: {
        type: 'string',
        title: 'Last Name',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input',
        'x-validator': [{ required: true, message: 'Last name is required' }]
      },
      email: {
        type: 'string',
        title: 'Email',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input',
        'x-validator': [
          { required: true, message: 'Email is required' },
          { format: 'email', message: 'Invalid email format' }
        ]
      },
      age: {
        type: 'number',
        title: 'Age',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'InputNumber',
        'x-validator': [
          { required: true, message: 'Age is required' },
          { minimum: 18, message: 'Must be at least 18' }
        ]
      }
    }
  }

  const SchemaField = createSchemaField({
    components: {
      Form,
      FormItem,
      Input,
      InputNumber,
      Button
    }
  })

  const handleSubmit = async () => {
    try {
      await form.validate()
      const values = form.values
      await submitForm(values)
      form.reset()
    } catch (error) {
      console.error('Validation errors:', error)
    }
  }

  return (
    <FormProvider form={form}>
      <Form labelCol={6} wrapperCol={16}>
        <SchemaField schema={schema} />
        <FormItem wrapperCol={{ offset: 6, span: 16 }}>
          <Button type="primary" onClick={handleSubmit}>
            Submit
          </Button>
        </FormItem>
      </Form>
    </FormProvider>
  )
}

From React Hook Form

Before: React Hook Form

import React from 'react'
import { useForm, SubmitHandler } from 'react-hook-form'
import { yupResolver } from '@hookform/resolvers/yup'
import * as Yup from 'yup'

interface FormData {
  username: string
  email: string
  password: string
  confirmPassword: string
}

const schema = Yup.object({
  username: Yup.string().required('Username is required'),
  email: Yup.string().email('Invalid email').required('Email is required'),
  password: Yup.string().min(8, 'Password must be at least 8 characters').required('Password is required'),
  confirmPassword: Yup.string().oneOf([Yup.ref('password')], 'Passwords must match').required('Confirm password is required')
})

const ReactHookFormExample: React.FC = () => {
  const { register, handleSubmit, formState: { errors }, watch } = useForm<FormData>({
    resolver: yupResolver(schema)
  })

  const watchedPassword = watch('password')

  const onSubmit: SubmitHandler<FormData> = (data) => {
    console.log(data)
    // Submit logic
  }

  return (
    <form onSubmit={handleSubmit(onSubmit)}>
      <div>
        <label>Username</label>
        <input {...register('username')} />
        {errors.username && <span>{errors.username.message}</span>}
      </div>

      <div>
        <label>Email</label>
        <input type="email" {...register('email')} />
        {errors.email && <span>{errors.email.message}</span>}
      </div>

      <div>
        <label>Password</label>
        <input type="password" {...register('password')} />
        {errors.password && <span>{errors.password.message}</span>}
      </div>

      <div>
        <label>Confirm Password</label>
        <input type="password" {...register('confirmPassword')} />
        {errors.confirmPassword && <span>{errors.confirmPassword.message}</span>}
      </div>

      <button type="submit">Submit</button>
    </form>
  )
}

After: Formily Version

import React from 'react'
import { createForm } from '@formily/core'
import { FormProvider, createSchemaField } from '@formily/react'
import { Form, FormItem, Input, Button } from '@formily/antd'

interface FormData {
  username: string
  email: string
  password: string
  confirmPassword: string
}

const FormilyReactHookFormExample: React.FC = () => {
  const form = createForm<FormData>({
    initialValues: {
      username: '',
      email: '',
      password: '',
      confirmPassword: ''
    },
    effects() {
      // Custom validation for password match
      onFieldChange('confirmPassword', ['value'], (field) => {
        const password = form.values.password
        const confirmPassword = field.value

        if (confirmPassword && password !== confirmPassword) {
          field.errors = ['Passwords must match']
        } else {
          field.errors = []
        }
      })
    }
  })

  const schema = {
    type: 'object',
    properties: {
      username: {
        type: 'string',
        title: 'Username',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input',
        'x-validator': [{ required: true, message: 'Username is required' }]
      },
      email: {
        type: 'string',
        title: 'Email',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input',
        'x-validator': [
          { required: true, message: 'Email is required' },
          { format: 'email', message: 'Invalid email format' }
        ]
      },
      password: {
        type: 'string',
        title: 'Password',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input.Password',
        'x-validator': [
          { required: true, message: 'Password is required' },
          { min: 8, message: 'Password must be at least 8 characters' }
        ]
      },
      confirmPassword: {
        type: 'string',
        title: 'Confirm Password',
        required: true,
        'x-decorator': 'FormItem',
        'x-component': 'Input.Password',
        'x-validator': [{ required: true, message: 'Please confirm your password' }]
      }
    }
  }

  const SchemaField = createSchemaField({
    components: {
      Form,
      FormItem,
      Input,
      Button
    }
  })

  const handleSubmit = async () => {
    try {
      await form.validate()
      const values = form.values
      console.log(values)
      // Submit logic
      form.reset()
    } catch (error) {
      console.error('Validation errors:', error)
    }
  }

  return (
    <FormProvider form={form}>
      <Form labelCol={6} wrapperCol={16}>
        <SchemaField schema={schema} />
        <FormItem wrapperCol={{ offset: 6, span: 16 }}>
          <Button type="primary" onClick={handleSubmit}>
            Submit
          </Button>
        </FormItem>
      </Form>
    </FormProvider>
  )
}

Migration Checklist

Pre-Migration Preparation

1. Analyze existing forms

   • Count total forms to migrate
   • Identify form complexity levels
   • Document validation logic
   • Note custom components used

2. Set up Formily

   • Install Formily packages
   • Configure TypeScript types
   • Set up Ant Design integration
   • Create basic form components

3. Plan migration strategy

   • Choose incremental vs complete rewrite
   • Define migration timeline
   • Assign team responsibilities
   • Set up testing strategy

Migration Steps

1. Convert form structure

   • Replace useState with createForm
   • Convert field definitions to schema
   • Update validation logic
   • Replace onChange handlers

2. Update validation

   • Convert Yup schemas to Formily validators
   • Implement custom validation rules
   • Set up async validation
   • Configure error messages

3. Migrate components

   • Replace Formik/React Hook Form components
   • Update Ant Design integration
   • Convert custom field components
   • Update form submission logic

4. Test migration

   • Unit test individual forms
   • Integration test form workflows
   • Test validation scenarios
   • Performance test large forms

Post-Migration

1. Validation

   • All forms render correctly
   • Validation works as expected
   • Form submission functions properly
   • TypeScript types are correct

2. Optimization

   • Remove unused dependencies
   • Optimize form performance
   • Update documentation
   • Train team on Formily

Common Migration Patterns

State Management Migration

// Before: Multiple useState hooks
const [name, setName] = useState('')
const [email, setEmail] = useState('')
const [errors, setErrors] = useState({})

// After: Single form instance
const form = createForm({
  initialValues: { name: '', email: '' }
})

Validation Migration

// Before: Manual validation
const validateForm = () => {
  const errors = {}
  if (!name) errors.name = 'Name is required'
  if (!email) errors.email = 'Email is required'
  setErrors(errors)
}

// After: Schema-based validation
const schema = {
  type: 'object',
  properties: {
    name: { type: 'string', required: true },
    email: { type: 'string', required: true, format: 'email' }
  }
}

Form Submission Migration

// Before: Manual submission handling
const handleSubmit = (e) => {
  e.preventDefault()
  if (validateForm()) {
    submitForm({ name, email })
  }
}

// After: Formily submission
const handleSubmit = async () => {
  await form.validate()
  submitForm(form.values)
}

Additional Resources

Templates

• templates/migration-template.tsx - Reusable migration template
• templates/validation-converter.ts - Validation logic converter utility

Reference Files

• references/migration-comparison.md - Side-by-side comparison table
• references/common-pitfalls.md - Migration pitfalls and solutions
• references/validation-mapping.md - Validation rule mapping guide

Migration Tools

• Use automated code migration scripts for simple forms
• Create custom transformation utilities for complex forms
• Implement gradual migration wrappers for mixed environments

Best Practices

1. Start simple - Migrate basic forms first to learn the pattern
2. Maintain type safety - Convert all forms to TypeScript
3. Test thoroughly - Validate each migrated form matches original behavior
4. Document changes - Keep track of migration decisions and patterns
5. Iterate gradually - Improve forms after initial migration
6. Monitor performance - Watch for performance issues in complex forms
7. Train the team - Ensure all developers understand Formily patterns
8. Plan for rollbacks - Keep original forms as backup during migration