Otter

Otter is a toolkit library to build UIs with go and templ

CLI

Install

go install github.com/martinmunillas/otter/cmd/otter@latest

Commands

otter init {githubUser}/{projectName} Will get you started to launch right away

otter dev Will launch a development server, make sure you have a PORT set in the environment variables

otter migrate run Will migrate all missing database migrations, database driver and migrations directory can be specified in the otter.json of your project

otter migrate new {description} Will generate a new migrations file for you

Configuration

Otter is configured through a otter.json file

// otter.json
{
    "dbDriver": "postgres",
    "migrationsDir": "./migrations/",
}

Packages

otter

Almost unstyled common UI components

otter/env

Environment variables utilities

otter/response/send

JSON and HTML response sender utilities

otter/api

Api utilities

otter/i18n

I18n utilities

Set up

First make sure you have some translations files

// en.json
{
    "helloWorld": "Hello World",
}

// es.json
{
    "helloWorld": "Hola Mundo",
}

Then read the file either at runtime or compile time and pass it to i18n.AddLocale()

Compile time

// translations.go
package translations

import (
	_ "embed"

	"github.com/martinmunillas/otter/i18n"
)
//go:embed en.json
var EnJson []byte

//go:embed es.json
var EsJson []byte


func init() {
	i18n.AddLocale("en", bytes.NewReader(translations.EnJson))
	i18n.AddLocale("es", bytes.NewReader(translations.EsJson))
}

Runtime

// main.go
package translations

import (
	"os"

	"github.com/martinmunillas/otter/i18n"
)

func main() {
	file, _ := os.Open("./translations/en.json")
	i18n.AddLocale("en", file)
	_ = file.Close()

	file, _ = os.Open("./translations/es.json")
	i18n.AddLocale("es", file)
	_ = file.Close()
}

You could even fetch the translations from a remote source Once you added your locales, make sure you use the i18n.Middleware()

// main.go
func main() {
	// ...
	_ = http.ListenAndServe(api.PortString(8080), i18n.Middleware(mux))
}

This middleware will make sure to set the user's locale to the context, making it available with i18n.FromContext()

Locale switching

The user's locale is determined by the otter-lang cookie but when it hasn't been set the 'Accept-Language' header will be used.

The otter-lang cookie will be set only whenever the user decides to change their default locale.

The middleware will enable a /set-locale endpoint which will read the locale key from the request body and set it to the otter-lang cookie.

You can create your own locale setters but there is already a i18n.LanguageSelector component that wraps this endpoint. You can style it from css as this is a <select /> element with a "language-selector" class.

Translations usage

For the use of translations in your templ files you only need to call i18n.T() with your context and the translation key.

// hello_world.templ
templ HelloWorld() {
    <h1>
        @i18n.T(ctx, "helloWorld")
    </h1>
}

If your translations contain raw html, for example "hello <b>world</b>", you can use i18n.RawT().

// hello_world.templ
templ HelloWorld() {
    <h1>
        @i18n.RawT(ctx, "helloWorld")
    </h1>
}

There are also replacements available, these are super useful when the content needs further styling or dynamic content.

// en.json
{
    "hello": "Hello {name}, we are {logo} and we are stoked to have you with us!"
}

// hello.templ
css logoStyles() {
    color: tomato;
    font-weight: 900;
    font-size: 0.875em;
}

templ Logo() {
    <p class={ logoStyles() }>AmazingStartup</p>
}

templ Hello(name string) {
    <h1>
        @i18n.T(ctx, "hello", map[string]any{
            name: name,
            logo: Logo(),
        })
    </h1>
}