impl Server Side Translations

packages/app/public/static/locales/index.js

@@ -1,2 +0,0 @@
-// !!DO NOT EDIT/REMOVE THIS FILE!!
-// entry point for @alienfast/i18next-loader

packages/app/src/pages/[[...path]].page.tsx

@@ -5,14 +5,15 @@ import ExtensibleCustomError from 'extensible-custom-error';
 import {
   NextPage, GetServerSideProps, GetServerSidePropsContext,
 } from 'next';
+import { serverSideTranslations } from 'next-i18next/serverSideTranslations';
 import dynamic from 'next/dynamic';
 import Head from 'next/head';
 import { useRouter } from 'next/router';
 
+
 // import { PageAlerts } from '~/components/PageAlert/PageAlerts';
 // import { PageComments } from '~/components/PageComment/PageComments';
 // import { useTranslation } from '~/i18n';
-import { isPopulated } from '~/interfaces/common';
 import { CrowiRequest } from '~/interfaces/crowi-request';
 // import { renderScriptTagByName, renderHighlightJsStyleTag } from '~/service/cdn-resources-loader';
 // import { useIndentSize } from '~/stores/editor';
@@ -21,7 +22,6 @@ import { CrowiRequest } from '~/interfaces/crowi-request';
 import { IPageWithMeta } from '~/interfaces/page';
 import { ISidebarConfig } from '~/interfaces/sidebar-config';
 import { PageModel, PageDocument } from '~/server/models/page';
-import { serializeUserSecurely } from '~/server/models/serializers/user-serializer';
 import UserUISettings, { UserUISettingsDocument } from '~/server/models/user-ui-settings';
 import { useSWRxCurrentPage, useSWRxPageInfo } from '~/stores/page';
 import {
@@ -29,6 +29,7 @@ import {
 } from '~/stores/ui';
 import loggerFactory from '~/utils/logger';
 
+
 // import { isUserPage, isTrashPage, isSharedPage } from '~/utils/path-utils';
 
 // import GrowiSubNavigation from '../client/js/components/Navbar/GrowiSubNavigation';
@@ -50,7 +51,9 @@ import {
   useNoCdn, useEditorConfig, useCsrfToken, useIsSearchScopeChildrenAsDefault, useCurrentPageId, useCurrentPathname, useIsSlackConfigured,
 } from '../stores/context';
 
-import { CommonProps, getServerSideCommonProps, useCustomTitle } from './commons';
+import {
+  CommonProps, getNextI18NextConfig, getServerSideCommonProps, useCustomTitle,
+} from './commons';
 // import { useCurrentPageSWR } from '../stores/page';
 
 
@@ -407,6 +410,17 @@ async function injectServerConfigurations(context: GetServerSidePropsContext, pr
   };
 }
 
+/**
+ * for Server Side Translations
+ * @param context
+ * @param props
+ * @param namespacesRequired
+ */
+async function injectNextI18NextConfigurations(context: GetServerSidePropsContext, props: Props, namespacesRequired?: string[] | undefined): Promise<void> {
+  const nextI18NextConfig = await getNextI18NextConfig(serverSideTranslations, context, namespacesRequired);
+  props._nextI18Next = nextI18NextConfig._nextI18Next;
+}
+
 export const getServerSideProps: GetServerSideProps = async(context: GetServerSidePropsContext) => {
   const req: CrowiRequest = context.req as CrowiRequest;
 
@@ -414,6 +428,7 @@ export const getServerSideProps: GetServerSideProps = async(context: GetServerSi
 
   const result = await getServerSideCommonProps(context);
 
+
   // check for presence
   // see: https://github.com/vercel/next.js/issues/19271#issuecomment-730006862
   if (!('props' in result)) {
@@ -437,6 +452,7 @@ export const getServerSideProps: GetServerSideProps = async(context: GetServerSi
 
   injectRoutingInformation(context, props, pageWithMeta);
   injectServerConfigurations(context, props);
+  injectNextI18NextConfigurations(context, props, ['translation']);
 
   if (user != null) {
     props.currentUser = JSON.stringify(user);

packages/app/src/pages/commons.ts

@@ -1,8 +1,11 @@
 import { DevidedPagePath } from '@growi/core';
 import { GetServerSideProps, GetServerSidePropsContext } from 'next';
-
+import { SSRConfig, UserConfig } from 'next-i18next';
 
 import { CrowiRequest } from '~/interfaces/crowi-request';
+import { Lang } from '~/interfaces/lang';
+
+import * as nextI18NextConfig from '../next-i18next.config';
 
 export type CommonProps = {
   namespacesRequired: string[], // i18next
@@ -13,7 +16,7 @@ export type CommonProps = {
   customTitleTemplate: string,
   csrfToken: string,
   growiVersion: string,
-}
+} & Partial<SSRConfig>;
 
 // eslint-disable-next-line max-len
 export const getServerSideCommonProps: GetServerSideProps<CommonProps> = async(context: GetServerSidePropsContext) => {
@@ -41,6 +44,25 @@ export const getServerSideCommonProps: GetServerSideProps<CommonProps> = async(c
   return { props };
 };
 
+export const getNextI18NextConfig = async(
+    // 'serverSideTranslations' method should be given from Next.js Page
+    //  because importing it in this file causes https://github.com/isaachinman/next-i18next/issues/1545
+    serverSideTranslations: (initialLocale: string, namespacesRequired?: string[] | undefined, configOverride?: UserConfig | null) => Promise<SSRConfig>,
+    context: GetServerSidePropsContext, namespacesRequired?: string[] | undefined,
+): Promise<SSRConfig> => {
+
+  const req: CrowiRequest = context.req as CrowiRequest;
+  const { crowi, user } = req;
+  const { configManager } = crowi;
+
+  // determine language
+  const locale = user?.lang
+    ?? configManager.getConfig('crowi', 'app:globalLang') as Lang
+    ?? Lang.en_US;
+
+  return serverSideTranslations(locale, namespacesRequired ?? ['translation'], nextI18NextConfig);
+};
+
 /**
  * Generate whole title string for the specified title
  * @param props