Hello Gophers!
In this article we will learn how to convert a single language web application to a multi language one.
Tools used in this article:
- iris
- go-bindata (optional)
First of all, create a directory that hosts your application, e.g. myapp, and install Iris:
$ go mod init myapp
$ go get github.com/kataras/iris/v12@master
Follow the tutorial below.
Internationalization and localization
Localization features provide a convenient way to retrieve strings in various languages, allowing you to easily support multiple languages within your application. Language strings are stored in files within the ./locales directory. Within this directory there should be a subdirectory for each language supported by the application:
│ main.go
└───locales
├───el-GR
│ home.yml
├───en-US
│ home.yml
└───zh-CN
home.yml
The default language for your application is the first registered language.
app := iris.New()
// First parameter: Glob filpath patern,
// Second variadic parameter: Optional language tags,
// the first one is the default/fallback one.
app.I18n.Load("./locales/*/*", "en-US", "el-GR", "zh-CN")
Or if you load all languages by:
app.I18n.Load("./locales/*/*")
// Then set the default language using:
app.I18n.SetDefault("en-US")
Load embedded locales
You may want to embed locales with a go-bindata tool within your application executable.
- install a go-bindata tool, e.g.
$ go get -u github.com/go-bindata/go-bindata/...
- embed local files to your application
$ go-bindata -o locales.go ./locales/...
- use the
LoadAssetsmethod to initialize and load the languages
^ The AssetNames and Asset functions are generated by go-bindata
ap.I18n.LoadAssets(AssetNames, Asset, "en-US", "el-GR", "zh-CN")
Defining Translations
Locale files can be written at YAML(recommended), JSON, TOML or INI form.
Each file should contain keys. Keys can have sub-keys(we call them "sections") too.
Each key's value should be of form string or map containing by its translated text (or template) or/and its pluralized key-values.
Iris i18n module supports pluralization out-of-the-box, see below.
Fmt Style
hi: "Hi %s!"
ctx.Tr("Hi", "John")
// Outputs: Hi John!
Template
hi: "Hi {{.Name}}!"
ctx.Tr("Hi", iris.Map{"Name": "John"})
// Outputs: Hi John!
Pluralization
Iris i18n supports plural variables. To define a per-locale variable you must
define a new section of Vars key.
The acceptable keys for variables are:
one-
"=x"where x is a number "<x"otherformat
Example:
Vars:
- Minutes:
one: "minute"
other: "minutes"
- Houses:
one: "house"
other: "houses"
Then, each message can use this variable, here's how:
# Using variables in raw string
YouLate: "You are %[1]d ${Minutes} late."
# [x] is the argument position,
# variables always have priority other fmt-style arguments,
# that's why we see [1] for houses and [2] for the string argument.
HouseCount: "%[2]s has %[1]d ${Houses}."
ctx.Tr("YouLate", 1)
// Outputs: You are 1 minute late.
ctx.Tr("YouLate", 10)
// Outputs: You are 10 minutes late.
ctx.Tr("HouseCount", 2, "John")
// Outputs: John has 2 houses.
You can select what message will be shown based on a given plural count.
Except variables, each message can also have its plural form too!
Acceptable keys:
zeroonetwo"=x""<x"">x"other
Let's create a simple plural-featured message, it can use the Minutes variable we created above too.
FreeDay:
"=3": "You have three days and %[2]d ${Minutes} off." # "FreeDay" 3,15
one: "You have a day off." # "FreeDay", 1
other: "You have %[1]d free days." # "FreeDay", 5
ctx.Tr("FreeDay", 3, 15)
// Outputs: You have three days and 15 minutes off.
ctx.Tr("FreeDay", 1)
// Outputs: You have a day off.
ctx.Tr("FreeDay", 5)
// Outputs: You have 5 free days.
Let's continue with a bit more advanced example, using template text + functions + plural + variables.
Vars:
- Houses:
one: "house"
other: "houses"
- Gender:
"=1": "She"
"=2": "He"
VarTemplatePlural:
one: "${Gender} is awesome!"
other: "other (${Gender}) has %[3]d ${Houses}."
"=5": "{{call .InlineJoin .Names}} are awesome."
const (
female = iota + 1
male
)
ctx.Tr("VarTemplatePlural", iris.Map{
"PluralCount": 5,
"Names": []string{"John", "Peter"},
"InlineJoin": func(arr []string) string {
return strings.Join(arr, ", ")
},
})
// Outputs: John, Peter are awesome
ctx.Tr("VarTemplatePlural", 1, female)
// Outputs: She is awesome!
ctx.Tr("VarTemplatePlural", 2, female, 5)
// Outputs: other (She) has 5 houses.
Sections
If the key is not a reserved one (e.g. one, two...) then it acts as a sub section. The sections are separated by dot characters (.).
Welcome:
Message: "Welcome {{.Name}}"
ctx.Tr("Welcome.Message", iris.Map{"Name": "John"})
// Outputs: Welcome John
Determining The Current Locale
You may use the context.GetLocale method to determine the
current locale or check if the locale is a given value:
func(ctx iris.Context) {
locale := ctx.GetLocale()
// [...]
}
The Locale interface looks like this.
// Locale is the interface which returns from a
// `Localizer.GetLocale` metod.
// It serves the transltions based on "key" or format. See `GetMessage`.
type Locale interface {
// Index returns the current locale index from the languages list.
Index() int
// Tag returns the full language Tag attached tothis Locale,
// it should be uniue across different Locales.
Tag() *language.Tag
// Language should return the exact languagecode of this `Locale`
//that the user provided on `New` function.
//
// Same as `Tag().String()` but it's static.
Language() string
// GetMessage should return translated text based n the given "key".
GetMessage(key string, args ...interface{}) string
}
Retrieving Translation
Use of context.Tr method as a shortcut to get a translated text for this request.
func(ctx iris.Context) {
text := ctx.Tr("hi", "name")
// [...]
}
Inside Views
func(ctx iris.Context) {
ctx.View("index.html", iris.Map{
"tr": ctx.Tr,
})
}
Thanks for reading 🙏 Have fun and be safe indoors 💪
Special thanks to Damon Blais
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