gen_lang
gen_lang is a dart library for internationalization. extracts messages
to generate dart files required by
intl.
now, three steps for internationalization
- preparing json files
- run gen_lang
- use it in coding
installation
add these libraries into pubspec.yaml
dependencies:
flutter_localizations:
sdk: flutter
dev_dependencies:
gen_lang: 0.1.3
usage
pub run gen_lang:generate
a below table shown all supported arguments:
| argument | description |
|---|---|
| –source-dir | a source folder contains all string json files (defaults to “res/string”) |
| –output-dir | a output folder stores all generated files (defaults to “lib/generated”) |
| –template-locale | use string_{template-locale}.json as a template to search key. if string_en does not exist, this script will use the first string json file as a template (defaults to “en”) |
source of json files
by default, the json files are required to locate at res/string. using
--source-dir argument can change the default source path. these files
must be named in this pattern string_{locale}.json
example of the files,
|--- lib
|--- res
|--- string
|--- string_en.json
|--- string_zh_tw.json
|--- string_ja.json
supported message type
simple message
define a json key and message without parameters
{
"simplemessage": "this is a simple message"
}
message with parameters
define a message with parameters. use ${parametername} in a message.
{
"messagewithparams": "hi ${yourname}, welcome you!"
}
plural messages with parameters
define messages in a plural form. ${how many} is a reserved parameter in
a plural message. this parameters support integer only. for intl,
intl.plural() supports these plural keyword including ‘zero’, ‘one’,
‘two’, ‘few’, ‘many’ and ‘other’. define a json key into this pattern
{jsonkey} {pluralkeyword}. for ‘other’, need to define ‘pother’ for the
plural keyword.
example
{
"pluralmessagezero": "hi ${interviewername}, i have no working experience.",
"pluralmessageone": "hi ${interviewername}, i have one year working experience.",
"pluralmessagetwo": "hi ${interviewername}, i have two years of working experience.",
"pluralmessagefew": "hi ${interviewername}, i have few years of working experience.",
"pluralmessagemany": "hi ${interviewername}, i worked for a long time.",
"pluralmessagepother": "hi ${interviewername}, i have ${howmany} years of working experience."
}
to know plural rules more, please read
intl’s plural rules
source code.
gender message with parameters
define a message in gender form. ${targetgender} is a reserved parameter
in a gender message. this parameters support string value with ‘male’,
female’ and ‘other’. for intl, intl.gender() supports these keyword
including ‘male’, ‘female’ and ‘other’. define a json key into this
pattern {jsonkey} {genderkeyword}. for ‘other’, need to define ‘gother’
for the gender keyword.
example
{
"gendermessagemale": "hi ${name}, he is boy.",
"gendermessagefemale": "hi ${name}, she is girl",
"gendermessagegother": "hi ${name}, he/she is boy/girl."
}
usage of i18n.dart
the script will generate two files into the output folder including
i18n.dart and messages_all.dart. import i18n.dart into your source
code. then finish internationalization tasks.
example
import 'package:gen_lang_example/generated/i18n.dart';
...
materialapp(
localizationsdelegates: [
s.delegate,
globalmateriallocalizations.delegate,
globalwidgetslocalizations.delegate
],
supportedlocales: s.delegate.supportedlocales,
...
...
s.of(context).simplemessage; // simple message
s.of(context).messagewithparams('developer'); // message with parameters
s.of(context).pluralmessage(10, 'king wu'); // plural message with parameters
s.of(context).gendermessage('male', 'king wu'); // gender message with parameters
running script in example
go into example folder. run the command
cd example
pub run gen_lang:generate
then will generate i18n.dart and messages_all.dart
