Migration guide from 2.x to 3.x¶

Important

Check out the @lingui/codemods package for semi-automatic migration of your codebase.

Backward incompatible changes¶

Minimal required versions are:

Node.js: 10.x
React: 16.8
Babel: 7

@lingui/react¶

<I18n> render-prop component was removed in favor of useLingui() hook.
In <I18nProvider>, defaultRender prop was renamed to defaultComponent, and now only accepts Custom Components
In <Trans>, defaults prop was renamed to message and description to comment.
In <Trans>, render prop only accepts render-prop function which is used to render translation.
In <Trans>, new prop component accepts React component which is used to render translation.
In <Trans>, components is now an object, not an array. When using the low level API, it allows to name the component placeholders:
```
<Trans id="Read <a>the docs</a>!" components={{a: <a href="/docs" />}} />
```
NumberFormat and DateFormat components were removed. Use date and number formats from @lingui/core package instead.

Removed <I18nProvider> declarative API¶

LinguiJS started as a React library. After @lingui/core package was introduced, there were two ways how to switch active locales and manage catalogs in React: either using <I18nProvider> declarative API or using setupI18n imperative API.

In the same spirit as @apollo/react and react-redux, the <I18nProvider> is simplified and accepts i18n manager, which must be created manually:

  import { I18nProvider } from '@lingui/react'
  import { i18n } from "@lingui/core"
+ import { en } from 'make-plural/plurals'
  import { messages } from './locale/en/messages.js'

+ i18n.loadLocaleData('en', { plurals: en })
+ i18n.load('en', messages)
+ i18n.activate('en')

  function App() {
     return (
-       <I18nProvider language="en" catalogs={{ en: catalogEn }}>
+       <I18nProvider i18n={i18n}>
           <App />
        </I18nProvider>
     )
  }

@lingui/core¶

Package now exports default i18n instance. It’s recommended to use it unless you need customized instance.
```
+ import { i18n } from "@lingui/core"
- import { setupI18n } from "@lingui/core"

- const i18n = setupI18n()
  i18n.activate('en')
```
Note

If you decide to use custom i18n instance, you also need to set runtimeConfigModule. Macros automatically import i18n instance and must be aware of correct import path.
i18n.t, i18n.plural, i18n.select and i18n.selectOrdinal methods were removed in favor of macros.
i18n.use was removed. Using two locales at the same time isn’t common usecase and can be solved in user land by having two instances of i18n object.

Signature of i18n._ method has changed. The third parameter now accepts default message in message prop, instead of defaults:

- i18n._('Welcome / Greetings', { name: 'Joe' }, { defaults: "Hello {name}" })
+ i18n._('Welcome / Greetings', { name: 'Joe' }, { message: "Hello {name}" })

i18n._ also accepts a message descriptor as a first parameter:

i18n._({
  id: string,
  message?: string,
  comment?: string
})

i18n.load loads a catalog for a single locale¶

i18n manager is the single source of truth and there’s no need to keep all catalogs loaded outside this object. To make loading easier, i18n.load now accepts catalog for a single locale or multiple catalogs at once.

  import { i18n } from "@lingui/core"
  import catalogEn from './locale/en/messages.js'

- i18n.load({ en: catalogEn })
+ i18n.load('en', catalogEn.messages)

Note

You can still use i18n.load to load all catalogs at once:

// i18n.js
import { i18n } from "@lingui/core"
import catalogEn from './locale/en/messages.js'
import catalogFr from './locale/fr/messages.js'

i18n.load({
   en: catalogEn.messages,
   fr: catalogFr.messages
})

@lingui/macro¶

plural, select and selectOrdinal accepts value as a first parameter:

- plural({ value, one: "# book", other: "# books" })
+ plural(value, { one: "# book", other: "# books" })

@lingui/cli¶

command lingui init was removed
command lingui add-locale was removed

Whitespace¶

Whitespace handling in plugins had few bugs. By fixing them, there might be few backward incompatible changes. It’s advised to run extract and inspect changes in catalogs (if any).

Spaces before {variables} in JSX aren’t preserved. This is how React handles whitespaces in JSX. Leading whitespace is always removed:
```
<Trans>
   &quot;
   {variable}
   &quot;
</Trans>

// Becomes: &quot;{variable}&quot;
```
Forced newlines are preserved. Sometimes it’s useful to keep newlines in JSX. If that’s your case, you need to force it in the same was as spaces are forced before variables or elements:
```
<Trans>
   1. Item{"\n"}
   2. Item
</Trans>

// Becomes: 1. Item\n2. Item
```

Plugins/Presets¶

Plugins are replaced with macros. Presets are removed completely because they aren’t needed anymore.

Uninstall plugins/presets, remove them from Babel config and replace them with macros:

npm uninstall @lingui/babel-preset-react
npm install --dev @lingui/macro babel-plugin-macros

{
   "presets": [
-      "@lingui/babel-preset-react"
   ],
   "plugins": [
+      "macros",
   ]
}

Import <Trans>, <Plural>, <Select> and <SelectOrdinal> from @lingui/macro:

- import { Trans } from "@lingui/react"
+ import { Trans } from "@lingui/macro"

Note

If you used <Trans> component without children, then keep the import from @lingui/react:

import { Trans } from "@lingui/react"

const CustomID = () => <Trans id="msg.id" />
const DynamicID = () => <Trans id={msgId} />

i18n.t(), i18n.plural(), i18n.select() and i18n.selectOrdinal() methods are removed and replaced with macros.

These macros automatically binds message to default i18n object:
```
  import { i18n } from "@lingui/core"
+ import { t } from "@lingui/macro"

- i18n.t`Hello World`
+ t`Hello World`
```

New features¶

i18n.load¶

i18n.load can now accept one catalog for specific locale. Useful for incremental loading of catalogs.

import { i18n } from "@lingui/core"

// Lingui v2 and v3
i18n.load({
  en: require("./locale/en/messages"),
  cs: require("./locale/cs/messages")
})

// Lingui v3 only
i18n.load('en', require("./locale/en/messages"))
i18n.load('cs', require("./locale/cs/messages"))

i18n.on(‘change’, callback)¶

Event change is fired anytime new catalogs are loaded or when locale is activated.