handle cookie

Author: dphang

packages/libs/core/src/route/locale.ts

@@ -1,5 +1,6 @@
 import { Manifest, Request, RoutesManifest } from "../types";
 import { IncomingMessage } from "http";
+import { parse } from "cookie";
 
 export const findDomainLocale = (
   req: IncomingMessage,
@@ -143,12 +144,25 @@ export async function getLocaleDomainRedirect(
     const languageHeader = req.headers["accept-language"];
     const acceptLanguage = languageHeader && languageHeader[0]?.value;
 
-    // Try to find the right domain to redirect to if needed
-    const Accept = await import("@hapi/accept");
-    const acceptLanguages = Accept.languages(acceptLanguage).map((lang) =>
-      lang.toLowerCase()
-    );
+    const headerCookies = req.headers.cookie
+      ? req.headers.cookie[0]?.value
+      : undefined;
+    // Use cookies first, otherwise use the accept-language header
+    let acceptLanguages: string[] = [];
+    if (headerCookies) {
+      const cookies = parse(headerCookies);
+      const nextLocale = cookies["NEXT_LOCALE"];
+      if (nextLocale) {
+        acceptLanguages = [nextLocale.toLowerCase()];
+      }
+    } else {
+      const Accept = await import("@hapi/accept");
+      acceptLanguages = Accept.languages(acceptLanguage).map((lang) =>
+        lang.toLowerCase()
+      );
+    }
 
+    // Try to find the right domain to redirect to if needed
     // First check current domain can support any preferred language, if so do not redirect
     const currentDomainData = domains.find(
       (domainData) => domainData.domain === host

packages/libs/core/tests/route/locale.test.ts

@@ -120,19 +120,21 @@ describe("Locale Utils Tests", () => {
     });
 
     it.each`
-      host                     | acceptLang              | expectedRedirect
-      ${"next-serverless.com"} | ${"en"}                 | ${undefined}
-      ${"next-serverless.com"} | ${"fr"}                 | ${"next-serverless.fr/test"}
-      ${"next-serverless.com"} | ${"fr;q=0.7, nl;q=0.9"} | ${"next-serverless.nl/test"}
-      ${"next-serverless.fr"}  | ${"es"}                 | ${"next-serverless.com/test"}
-      ${"next-serverless.fr"}  | ${"en-GB"}              | ${"next-serverless.com/test"}
+      host                     | acceptLang              | cookie              | expectedRedirect
+      ${"next-serverless.com"} | ${"en"}                 | ${undefined}        | ${undefined}
+      ${"next-serverless.com"} | ${"fr"}                 | ${undefined}        | ${"next-serverless.fr/test"}
+      ${"next-serverless.com"} | ${"fr;q=0.7, nl;q=0.9"} | ${undefined}        | ${"next-serverless.nl/test"}
+      ${"next-serverless.fr"}  | ${"es"}                 | ${undefined}        | ${"next-serverless.com/test"}
+      ${"next-serverless.fr"}  | ${"en-GB"}              | ${undefined}        | ${"next-serverless.com/test"}
+      ${"next-serverless.com"} | ${"en"}                 | ${"NEXT_LOCALE=fr"} | ${"next-serverless.fr/test"}
     `(
-      "host: $host with accept-language: $acceptLang redirects to $expectedRedirect",
-      async ({ host, acceptLang, expectedRedirect }) => {
+      "host: $host with accept-language: $acceptLang and cookie: $cookie redirects to $expectedRedirect",
+      async ({ host, acceptLang, cookie, expectedRedirect }) => {
         const req = {
           headers: {
             host: [{ key: "Host", value: host }],
-            "accept-language": [{ key: "Accept-Language", value: acceptLang }]
+            "accept-language": [{ key: "Accept-Language", value: acceptLang }],
+            cookie: [{ key: "Cookie", value: cookie }]
           },
           uri: "/test"
         };