astro/.changeset/little-hornets-give.md

astro
minor

Adds a new i18n routing option manual to allow you to write your own i18n middleware:

import { defineConfig } from "astro/config"
// astro.config.mjs
export default defineConfig({
    i18n: {
        locales: ["en", "fr"],
        defaultLocale: "fr",
        routing: "manual"
    }
})

Adding routing: "manual" to your i18n config disables Astro's own i18n middleware and provides you with helper functions to write your own: redirectToDefaultLocale, notFound, and redirectToFallback:

// middleware.js
import { redirectToDefaultLocale } from "astro:i18n";
export const onRequest = defineMiddleware(async (context, next) => {
    if (context.url.startsWith("/about")) {
        return next()
    } else {
        return redirectToDefaultLocale(context, 302);  
    }
})

Also adds a middleware function that manually creates Astro's i18n middleware. This allows you to extend Astro's i18n routing instead of completely replacing it. Run middleware in combination with your own middleware, using the sequence utility to determine the order:

import {defineMiddleware, sequence} from "astro:middleware";
import { middleware } from "astro:i18n"; // Astro's own i18n routing config

export const userMiddleware = defineMiddleware();

export const onRequest = sequence(
  userMiddleware,
  middleware({
    redirectToDefaultLocale: false,
    prefixDefaultLocale: true
  })
)