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react-g11n

An internationalisation and localization library for React.

Installation

npm install react-g11n

Usage

The provider pattern is used to wrap your component and provide a translator object to child components. Wrap your component in a Localizer as follows:

import { render } from "react-dom"
import { Localizer } from "react-g11n"

import App from "app"

render(
    <Localizer locale="cy" localeDir="./locale">
        <App />
    </Localizer>
}

From within a child component you can gain access to a translator property as follows:

import React, { PropTypes} from "react"
import { localize } from "react-g11n"

class MyComponent extends React.Component {

    render() {
        const { translator } = this.props

        return (
            <h1>{translator.gettext('Hello world!')}</h1>
        )

}

MyComponent.propTypes = {
    translator: PropTypes.object.isRequired
}

export default localize(MyComponent)

The translate object exposes the a Gettext object with common gettext functions

Working with gettext translation files

GNU gettext is an internationalization and localization system commonly used on Unix like operating systems.

Three types of files are used in the GNU gettext translation framework:

  • .pot (Portable Object Template) files

    A .pot file is created by a program which searches through a projects source code and picks out every message identifier passed to gettext translation functions. The list of message identifiers is placed into a .pot file which serves as a template for creating .po files.

  • .po (Portable Object) files

    A .po file is derived from the template and fills out the translations.

  • .mo (Machine Object) files

    A .po file is compiled into a binary .mo file optimized for reading by a machine.

Extracting messages

To extract messages from javascript files use jsxgettext which can be installed from npm:

npm install jsxgettext --save-dev

This will install a command called jsxgettext which can be used to scan javascript code for calls to gettext and extract translations into a portable object template:

mkdir -p src/locale
node_modules/.bin/jsxgettext src/**/*.js -o src/locale/messages.pot

This will output a .pot file to src/locale/messages.pot

Initializing a message catalog file

Once messages have been extracted into a .pot file this can be used to generate a .po file. A .po file contains translations for a set of messages for a particular locale. The Gettext msginit command can be used to initialize a .po file:

cd src/locale
mkdir -p cy/LC_MESSAGES
msginit -l cy -o cy/LC_MESSAGES/messages.po

This will create a new message catalog .po file which can then be edited by a human translator using a tool such as Poedit.

Updating a message catalog file

As more translation strings are added, or as existing strings are changed it will be neccessary to update existing .po files so that new and changed messages can be translated.

First regenerate the .pot file as per the Extracting messages section and then use the msgmerge command from Gettext.

cd src/locale
msgmerge --update cy/LC_MESSAGES/messages.po messages.pot

Compiling a message catalog file

To convert translation files into a machine readable binary file use the Gettext msgfmt command to convert .po files into .mo files.

cd src/locale
msgfmt cy/LC_MESSAGES/messages.po -o cy/LC_MESSAGES/messages.mo

Automating with Make

To make the above commands easier, the can be codified into Makefile targets to provide the following phony targets:

  • extract-messages
  • update-catalog
  • compile-catalog

An example Makefile would be:

SRC_DIR = src/
POT_FILE = $(SRC_DIR)/locale/messages.pot
PO_FILES := $(shell find $(SRC_DIR) -type f -name '*.po')
MO_FILES := $(patsubst $(SRC_DIR)/%.po,$(SRC_DIR)/%.mo,$(PO_FILES))

JSXGETTEXT_CMD = node_modules/.bin/jsxgettext

.PHONY: extract-messages
extract-messages:			## Extract translations from source code
        $(JSXGETTEXT_CMD) $(SRC_DIR)/**/*.js -o $(POT_FILE)

.PHONY: update-catalog
update-catalog: $(PO_FILES)		## Update messages catalogs for all locales

$(PO_FILES): $(POT_FILE)
        msgmerge --previous $@ $? -o $@

.PHONY: compile-catalog
compile-catalog: $(MO_FILES)	## Compile messages catalogs for all locales

$(MO_FILES): $(SRC_DIR)/%.mo: $(SRC_DIR)/%.po
        mkdir -p $(@D)
        msgfmt $< -o $@

A translation workflow would then be:

make extract-messages
make update-catalog

Once translations of the generate .po files has taken place the .mo files can be compiled with:

make compile-catalog