migrate◉ LIVE — Updated Feb 25, 20262,847 methods indexed
a/src/components/UserProfile.jsx→b/src/components/UserProfile.tsx
$migrate --describe
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Rails 6→7React HooksPython 3.xNext.js 14Vue 3
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TELEMETRYLIVELast updated: 2026-02-25 06:34 UTC
0
deprecated methods mapped
across all indexed frameworks
0
frameworks covered
from Rails to Kubernetes
0%
avg. migration time reduced
based on 340 team surveys
0+
engineers use this weekly
across 89 countries
$migrate list --format=diff
Migration Reference Tables
Every entry is production-verified. Copy the new syntax directly. Sorted by complexity tier.
9 results
Tier 1Simple renames & direct replacements
Tier 1React / Lifecycle MethodscomponentWillMount → useEffect
− DEPRECATEDbefore
class UserProfile extends Component {
componentWillMount() {
this.fetchUser(this.props.id);
}
}
+ MODERNafter
function UserProfile({ id }) {
useEffect(() => {
fetchUser(id);
}, [id]);
}
//componentWillMount is removed in React 18. Runs before render in class components, but useEffect runs after.
Tier 1React / Lifecycle MethodscomponentWillReceiveProps → useEffect deps
− DEPRECATEDbefore
componentWillReceiveProps(nextProps) {
if (nextProps.id !== this.props.id) {
this.fetchData(nextProps.id);
}
}
+ MODERNafter
useEffect(() => {
fetchData(id);
}, [id]); // re-runs when id changes
//Dependency array in useEffect replaces manual prop comparison.
Tier 1Rails / Model Associationsbelongs_to optional behavior change
− DEPRECATEDbefore
# Rails 4/5: belongs_to was optional by default
class Comment < ApplicationRecord
belongs_to :post
# post_id could be nil — no validation error
end
+ MODERNafter
# Rails 6+: belongs_to required by default
class Comment < ApplicationRecord
belongs_to :post
# OR explicitly optional:
belongs_to :post, optional: true
end
//Rails 5+ made belongs_to required by default. Missing foreign keys now raise validation errors.
Tier 1Python / Built-in Functionsprint statement → print() function
− DEPRECATEDbefore
# Python 2
print "Hello, world" print"Value:", x
print >> sys.stderr, "Error"
+ MODERNafter
# Python 3
print("Hello, world")
print("Value:", x)
print("Error", file=sys.stderr)
//print is a function in Python 3. Run 2to3 to automate this migration.
Preview complete. 2,847 more entries in the full guide.
Includes edge cases, version flags, and CLI migration scripts.
Tier 2Structural refactors — moderate complexity
Tier 2React / State ManagementLegacy Context API → createContext
− DEPRECATEDbefore
// Old Context (deprecated)
class ThemeProvider extends Component {
getChildContext() {
return { theme: this.state.theme };
}
static childContextTypes = {
theme: PropTypes.string
};
}
// Consumer
Component.contextTypes = { theme: PropTypes.string };
+ MODERNafter
// Modern Context API
const ThemeContext = createContext('light');
function ThemeProvider({ children }) {
const [theme, setTheme] = useState('light');
return (
<ThemeContext.Provider value={theme}>
{children}
</ThemeContext.Provider>
);
}
// Consumer
const theme = useContext(ThemeContext);
Tier 2Rails / Configurationsecrets.yml → credentials.yml.enc
− DEPRECATEDbefore
# config/secrets.yml (Rails 4/5)
production:
secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>
api_key: my_plain_text_key
# Access via:
Rails.application.secrets.api_key
+ MODERNafter
# config/credentials.yml.enc (Rails 5.2+)
# Edit with: rails credentials:edit
api_key: my_encrypted_key
aws:
access_key_id: 123
# Access via:
Rails.application.credentials.api_key
Rails.application.credentials.aws[:access_key_id]
//credentials.yml.enc is encrypted and safe to commit. Requires master.key (never commit this).
Tier 2Next.js / RoutingPages Router → App Router
− DEPRECATEDbefore
// pages/users/[id].tsx (Pages Router)
import { GetServerSideProps } from 'next';
export const getServerSideProps: GetServerSideProps = async (ctx) => {
const user = await fetchUser(ctx.params.id);
return { props: { user } };
};
export default function UserPage({ user }) {
return <div>{user.name}</div>;
}
+ MODERNafter
// app/users/[id]/page.tsx (App Router)
// Server Component by default — no "use client" needed
async function UserPage({ params }: { params: { id: string } }) {
const user = await fetchUser(params.id); // Direct async/await
return <div>{user.name}</div>;
}
export default UserPage;
//App Router components are React Server Components by default. No need for getServerSideProps.
Tier 3Architectural pattern shifts — high complexity
Tier 3Python / ConcurrencyThreading callbacks → async/await
− DEPRECATEDbefore
# Python 2 / early Python 3 threading
import threading
def fetch_data(url, callback):
def _fetch():
result = urllib2.urlopen(url).read()
callback(result)
thread = threading.Thread(target=_fetch)
thread.start()
fetch_data(url, lambda r: process(r))
+ MODERNafter
# Python 3.5+ asyncio
import asyncio
import aiohttp
async def fetch_data(url: str) -> bytes:
async with aiohttp.ClientSession() as session:
async with session.get(url) as response:
return await response.read()
async def main():
result = await fetch_data(url)
process(result)
asyncio.run(main())
//asyncio is the standard for I/O-bound concurrency in Python 3. Much lower overhead than threads.
Tier 3Rails / File UploadsPaperclip → Active Storage
− DEPRECATEDbefore
# Gemfile — Paperclip (deprecated)
gem 'paperclip'
# Model
class User < ApplicationRecord
has_attached_file :avatar,
styles: { thumb: "100x100>" },
default_url: "/images/missing.png"
validates_attachment_content_type :avatar,
content_type: /Aimage/.*z/
end
# View
image_tag @user.avatar.url(:thumb)
+ MODERNafter
# No gem needed — Active Storage built-in
# Run: rails active_storage:install && rails db:migrate
# Model
class User < ApplicationRecord
has_one_attached :avatar
end
# Controller — no changes needed, accepts same params
# View
<%= image_tag @user.avatar.variant(resize_to_limit: [100, 100]) %>
# Migrate existing files:
# rails paperclip:convert
//Active Storage ships with Rails 5.2+. Run the Paperclip migration task to move existing attachments.
$migrate list --frameworks
14 Frameworks Indexed
// 3,367 total entries · updated weekly
Kubernetes
BETA1.20→1.29
API deprecations, Gateway API
Coming soon
GraphQL
BETA14→16
Schema changes, Nullability
Coming soon
Laravel
SOON8→11
Livewire, Folio, Volt
Coming soon
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