Implemented i18n cache busting

package.json

@@ -15,7 +15,7 @@
     "analyze": "webpack-bundle-analyzer dist/browser/stats.json",
     "build": "ng build --configuration development",
     "build:stats": "ng build --stats-json",
-    "build:prod": "yarn run build:ssr",
+    "build:prod": "cross-env NODE_ENV=production yarn run build:ssr",
     "build:ssr": "ng build --configuration production && ng run dspace-angular:server:production",
     "test": "ng test --source-map=true --watch=false --configuration test",
     "test:watch": "nodemon --exec \"ng test --source-map=true --watch=true --configuration test\"",

src/ngx-translate-loaders/translate-browser.loader.ts

@@ -5,6 +5,7 @@ import { NGX_TRANSLATE_STATE, NgxTranslateState } from './ngx-translate-state';
 import { hasValue } from '../app/shared/empty.util';
 import { map } from 'rxjs/operators';
 import { of as observableOf, Observable } from 'rxjs';
+import { environment } from '../environments/environment';
 
 /**
  * A TranslateLoader for ngx-translate to retrieve i18n messages from the TransferState, or download
@@ -33,9 +34,10 @@ export class TranslateBrowserLoader implements TranslateLoader {
     if (hasValue(messages)) {
       return observableOf(messages);
     } else {
+      const translationHash: string = environment.production ? `.${(process.env.languageHashes as any)[lang + '.json5']}` : '';
       // If they're not available on the transfer state (e.g. when running in dev mode), retrieve
       // them using HttpClient
-      return this.http.get('' + this.prefix + lang + this.suffix, { responseType: 'text' }).pipe(
+      return this.http.get(`${this.prefix}${lang}${translationHash}${this.suffix}`, { responseType: 'text' }).pipe(
         map((json: any) => JSON.parse(json))
       );
     }

src/ngx-translate-loaders/translate-server.loader.ts

@@ -23,8 +23,9 @@ export class TranslateServerLoader implements TranslateLoader {
    * @param lang the language code
    */
   public getTranslation(lang: string): Observable<any> {
+    const translationHash: string = (process.env.languageHashes as any)[lang + '.json5'];
     // Retrieve the file for the given language, and parse it
-    const messages = JSON.parse(readFileSync(`${this.prefix}${lang}${this.suffix}`, 'utf8'));
+    const messages = JSON.parse(readFileSync(`${this.prefix}${lang}.${translationHash}${this.suffix}`, 'utf8'));
     // Store the parsed messages in the transfer state so they'll be available immediately when the
     // app loads on the client
     this.storeInTransferState(lang, messages);

webpack/helpers.ts

@@ -1,18 +1,49 @@
-const path = require('path');
+import { readFileSync, readdirSync, statSync, Stats } from 'fs';
+import { join, resolve } from 'path';
+
+const md5 = require('md5');
 
 export const projectRoot = (relativePath) => {
-  return path.resolve(__dirname, '..', relativePath);
+  return resolve(__dirname, '..', relativePath);
 };
 
 export const globalCSSImports = () => {
   return [
-    projectRoot(path.join('src', 'styles', '_variables.scss')),
-    projectRoot(path.join('src', 'styles', '_mixins.scss')),
+    projectRoot(join('src', 'styles', '_variables.scss')),
+    projectRoot(join('src', 'styles', '_mixins.scss')),
   ];
 };
 
+/**
+ * Calculates the md5 hash of a file
+ *
+ * @param filePath The path of the file
+ */
+export function calculateFileHash(filePath: string): string {
+  const fileContent: Buffer = readFileSync(filePath);
+  return md5(fileContent);
+}
 
-module.exports = {
-  projectRoot,
-  globalCSSImports
-};
+/**
+ * Calculate the hashes of all the files (matching the given regex) in a certain folder
+ *
+ * @param folderPath The path of the folder
+ * @param regExp A regex of the files in the folder for which a hash needs to be generated
+ */
+export function getFileHashes(folderPath: string, regExp: RegExp): { [fileName: string]: string } {
+  const files: string[] = readdirSync(folderPath);
+  let hashes: { [fileName: string]: string } = {};
+
+  for (const file of files) {
+    if (file.match(regExp)) {
+      const filePath: string = join(folderPath, file);
+      const stats: Stats = statSync(filePath);
+
+      if (stats.isFile()) {
+        hashes[file] = calculateFileHash(filePath);
+      }
+    }
+  }
+
+  return hashes;
+}

webpack/webpack.common.ts

@@ -1,4 +1,5 @@
-import { globalCSSImports, projectRoot } from './helpers';
+import { globalCSSImports, projectRoot, getFileHashes, calculateFileHash } from './helpers';
+import { EnvironmentPlugin } from 'webpack';
 
 const CopyWebpackPlugin = require('copy-webpack-plugin');
 const path = require('path');
@@ -18,12 +19,13 @@ export const copyWebpackOptions = {
         // use [\/|\\] to match both POSIX and Windows separators
         const matches = absoluteFilename.match(/.*[\/|\\]assets[\/|\\](.+)\.json5$/);
         if (matches) {
+          const fileHash: string = process.env.NODE_ENV === 'production' ? `.${calculateFileHash(absoluteFilename)}` : '';
           // matches[1] is the relative path from src/assets to the JSON5 file, without the extension
-          return path.join('assets', matches[1] + '.json');
+          return path.join('assets', `${matches[1]}${fileHash}.json`);
         }
       },
       transform(content) {
-        return JSON.stringify(JSON5.parse(content.toString()))
+        return JSON.stringify(JSON5.parse(content.toString()));
       }
     },
     {
@@ -77,6 +79,9 @@ const SCSS_LOADERS = [
 
 export const commonExports = {
   plugins: [
+    new EnvironmentPlugin({
+      languageHashes: getFileHashes(path.join(__dirname, '..', 'src', 'assets', 'i18n'), /.*\.json5/g),
+    }),
     new CopyWebpackPlugin(copyWebpackOptions),
   ],
   module: {