feat(i18n): add language preference management functionality by Ang-m4 · Pull Request #786 · openedx/frontend-platform

Ang-m4 · 2025-04-01T19:37:36Z

Language Management Module

Description

This PR intents to add a new LanguageManager module to standardize language switching functionality. The module provides a new API for handling language changes from any component in the application.

Key Features

Unified Language Management: Centralizes all language-related operations into a single module
Complete Language Switching Flow: Handles the entire language change process through a single function call
User Preference Persistence: Updates both client-side cookies and server-side user preferences
Session Management: Integrates with LMS backend to ensure consistent language experience
RTL Support: Automatically handles right-to-left language adjustments
Event System Integration: Publishes events when locale changes to allow components to react

Implementation Details

New Functions

changeUserSessionLanguage(languageCode): Main public function that orchestrates the language change process:
- Sets the language cookie
- Updates authenticated user preferences in the backend (if applicable)
- Updates the session language
- Publishes a locale change event
- Handles RTL adjustments
updateUserPreferences(username, preferenceData): Updates server-side user language preferences via the API
setSessionLanguage(languageCode): Sets the language for the current session using the LMS setlang endpoint

API Usage

Components can now implement language switching with a single function call:

import { changeUserSessionLanguage } from '@edx/frontend-platform/i18n';

// When a user selects a new language
changeUserSessionLanguage('ar'); // Switch to Arabic

Related Work

This functionality is a core dependency for the Language Selector Implementation.

openedx-webhooks · 2025-04-01T19:37:40Z

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arbrandes

I think it is a good idea to have this logic be centralized in frontend-platform, instead of implemented as part of language selection dropdowns. I imagine openedx/frontend-component-footer#493 will have to be refactored accordingly, correct?

I have a minor suggested change, but I'm also not approving yet as I'd like to see PRs that use this.

src/i18n/LanguageManager.js

dcoa · 2025-06-13T01:50:39Z

I was thinking about the list of supported languages to display

I'm thinking as default use an array provided for frontend-platform using the messages object here that is configured during the MFE initialize. So the manager could return a function or variable with the list of locales Object.keys(messages)

@arbrandes what do you thing?

In that way we can get rid of SITE_SUPPORTED_LANGUAGES here, and in any case someone want to pass a more restricted or controlled list, they can do it by the plugin configuration.

codecov · 2025-06-18T19:26:44Z

Codecov Report

❌ Patch coverage is 96.42857% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 87.31%. Comparing base (acf0d46) to head (729b314).
⚠️ Report is 27 commits behind head on master.

Files with missing lines	Patch %	Lines
src/i18n/lib.js	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #786      +/-   ##
==========================================
+ Coverage   87.13%   87.31%   +0.18%     
==========================================
  Files          48       50       +2     
  Lines        1407     1435      +28     
  Branches      297      305       +8     
==========================================
+ Hits         1226     1253      +27     
- Misses        168      169       +1     
  Partials       13       13

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dcoa · 2025-06-19T12:41:14Z

src/i18n/languageManager.js

+  const formData = new FormData();
+  formData.append('language', languageCode);
+
+  const url = `${getConfig().LMS_BASE_URL}/i18n/setlang/`;


I was digging a little bit in edx-platform to see how the mako templates manage the logic and I found this endpoint, it is used for update no-authenticated users as you can see in the mako template.

The endpoint request a CSRF token as you can see here. I just want to make sure the following line of code is correct as a suggested change from the frontend-platform perspective (getAuthenticatedHttpClient is the right service to use? -@arbrandes could you help me with this doubt?-).

getAuthenticatedHttpClient().patch(`${getConfig().LMS_BASE_URL}/lang_pref/update_language`, {"pref-lang": languageCode}, { isPublic: true })

In this way we can avoid setting the language cookie (as currently happen with the lines 81-83 of the this PR), and it will be 100% managed for the backend in both authenticated and unauthenticated users.

I create a sandbox for testing in learning, and the current endpoint can manage the authenticated and unauthenticated case (I have the problem in my dev environment only)

https://app.pr-1741-1395ab.sandboxes.opencraft.hosting/learning/course/course-v1:Demo+CT01+CT01/home

c.c @arbrandes

@dcoa, you say the endpoint can manage both authenticated and unauthenticated cases, but then mention a problem. Do you still think we can use the update_language endpoint here instead of Django's setlang?

I update my environment and tested it again and the /i18n/setlang/ endpoint works with the authenticated and unauthenticated users in both production like and dev environments.

So we can set the language using it and make the backend handle the cookie update. For the unauthenticated user will create a session cookie meanwhile for a authenticated user creates a cookie with expiration date.

Then the change is not needed.

Ang-m4 · 2025-06-25T16:05:37Z

Hi @arbrandes,

I made some changes to the code as you requested. Please let me know what you think:

Created a new languageApi module for easier testing.
Added an optional flag for reloading the page if needed.
Added a unit test.

and i would like to know your thoughts on @dcoa’s comments!

The endpoint request a CSRF token as you can see here. I just want to make sure the following line of code is correct as a suggested change from the frontend-platform perspective (getAuthenticatedHttpClient is the right service to use? -@arbrandes could you help me with this doubt?-).

I'm thinking as default use an array provided for frontend-platform using the messages object here that is configured during the MFE initialize. So the manager could return a function or variable with the list of locales Object.keys(messages)

Thank you so much for your time on this!

dcoa · 2025-08-25T21:32:07Z

@arbrandes friendly tag for reviewing here. Thank you!

felipemontoya · 2025-09-03T20:52:35Z

@arbrandes friendly ping again. To not be a constant bother since I know you are deepdiving in the frontendbase stuff, I'd like to ask if you need to pass this to someone else to be a reviewer here.

arbrandes

A couple of changes requested, and one pending change based on @dcoa's findings.

As for the list of supported languages, I completely agree that the list should come from the messages array, which can itself be changed by operators by other mechanisms. And it's also a good idea to have a getter function provided by i18n/lib.

Otherwise, this is looking good. Apologies for the delay in getting to the review!

arbrandes · 2025-09-19T15:14:52Z

src/i18n/languageManager.js

+  cookies.set(cookieName, languageCode);
+
+  try {
+    const user = getAuthenticatedUser();


I believe the call to getAuthenticatedUser() would be more at home in languageApi.js. username is only used there, anyway.

arbrandes · 2025-09-19T15:17:38Z

src/i18n/languageApi.js

+ * @returns {Promise} - A promise that resolves when the API call completes successfully,
+ *                      or rejects if there's an error with the request.
+ */
+export async function updateUserPreferences(username, preferenceData) {


As suggested in another review comment, I would change this function like so:

Suggested change

export async function updateUserPreferences(username, preferenceData) {

export async function updateAuthenticatedUserPreferences(preferenceData) {

And then get the authenticated username inside the function. Unless, of course, you can imagine a situation where we'd need this function to change the preference of some user other than the currently logged in one - but I find that to be unlikely.

arbrandes · 2025-09-19T15:28:24Z

src/i18n/languageApi.js

+  formData.append('language', languageCode);
+
+  return getAuthenticatedHttpClient().post(
+    `${getConfig().LMS_BASE_URL}/i18n/setlang/`,


I'm adding a "pending" note here regarding @dcoa's findings on this other conversation. If the update_language endpoint works, we should probably use it.

Yes, we should use the update_language API indeed. It touches the database.

@Ang-m4, any objections to implementing this?

sadly @Ang-m4 has recently left our team. @dcoa, do you think this work is something you could continue?

arbrandes · 2025-09-19T15:31:09Z

src/i18n/languageManager.js

+  const cookies = getCookies();
+  const cookieName = getConfig().LANGUAGE_PREFERENCE_COOKIE_NAME;
+  cookies.set(cookieName, languageCode);


As per this other conversation, if we can leverage the update_language endpoint to set the cookie, we should. This is an if, though.

arbrandes · 2025-09-19T15:33:37Z

src/i18n/languageManager.js

+  const formData = new FormData();
+  formData.append('language', languageCode);
+
+  const url = `${getConfig().LMS_BASE_URL}/i18n/setlang/`;


@dcoa, you say the endpoint can manage both authenticated and unauthenticated cases, but then mention a problem. Do you still think we can use the update_language endpoint here instead of Django's setlang?

dcoa · 2025-10-08T12:53:05Z

This LGTM!! thank you, @Ang-m4 .

@arbrandes the PR was updated accordingly to the feedback, could you please verify?

Asespinel · 2025-11-26T02:58:53Z

We've successfully implemented the language selector feature on our end and everything is working well.

The only question we have is regarding the getSupportedLocaleList() function behavior. Currently, this function returns all available languages with translations, rather than filtering based on the SITE_SUPPORTED_LANGUAGES configuration.

We implemented a client-side workaround in the LanguageSelector component to filter the languages

Is this the intended behavior, or should getSupportedLocaleList() respect the SITE_SUPPORTED_LANGUAGES configuration automatically? @arbrandes Would you mind taking a look at this when you get a chance? Would appreciate your thoughts on the expected behavior here. Thanks!

mphilbrick211 · 2026-01-22T22:37:42Z

Friendly ping on this, @arbrandes

arbrandes

I can't find anything to object to architecturally, but we might be missing the ability for operators to restrict the list of languages the user can select from. See the inline question below.

arbrandes · 2026-01-28T13:54:43Z

src/i18n/languageApi.js

+  formData.append('language', languageCode);
+
+  return getAuthenticatedHttpClient().post(
+    `${getConfig().LMS_BASE_URL}/i18n/setlang/`,


@Ang-m4, any objections to implementing this?

arbrandes · 2026-01-28T14:19:06Z

src/i18n/lib.js

+ * @returns {string[]} Array of supported locale codes
+ * @memberof module:Internationalization
+ */
+export function getSupportedLocaleList() {


@Asespinel poses a great question: shouldn't we allow the operator to manually define which languages are actually available for use or selection by the end user, independently of the locales derived from messages?

I believe we should. In the pre-MFE world this was possible via a call to released_languages(), which in turn consulted the DarkLangConfig model.

In the header PR that goes along with this one there's a reference to a SITE_SUPPORTED_LANGUAGES config item, but I don't see it implemented anywhere.

What do? 1) a call to released_languages on the backend, or 2) a new frontend-only configuration?

Personally, I think either would be sufficient, but probably 2) is easier to implement and has less potential for UX problems. I can also see a path where 2) is configurable at runtime via MFE_CONFIG.

(Tangent: if we don't go with 1) and don't foresee ever needing the features of DarkLang - such as the ability to test fake/beta languages by adding a ?langPref=english@pirate query to the URL - we should deprecate the DarkLang thing.)

@brian-smith-tcril, @dcoa, @felipemontoya: thoughts?

Oh, I was just researching some of this recently. The whole thing seems a bit messy. Sounds like you might have some insight to share on openedx/openedx-platform#38036

In the header PR that goes along with this one there's a reference to a SITE_SUPPORTED_LANGUAGES config item, but I don't see it implemented anywhere.

That was previously implement but we change it to pass the languages as props for the slot refactor.

Here is in the footer PR commit as reference openedx/frontend-component-footer@82bfc97#diff-618acf142786bf7414152d4982d3d647b5ca1f96edaed7385ba0f17b46741b65R63-R64 and the comment that mention the idea #786 (comment)

I think for now, just to keep consistency with the legacy code and the templates that allow to select the language in header and footer there, having a single source of true DarkLang is ideal (I ignore if we have a current endpoint to return the information, I think no, right?). However, looking ahead, once the UI becomes fully client-side rendered, I don’t see much value (at least from the frontend perspective) in keeping DarkLang feature. In that scenario, I would prefer to manage it through a configuration variable instead.

OmarIthawi · 2026-02-24T13:16:45Z

@bradenmacdonald, one more area to look at, regarding languages.

cc: @shadinaif

bradenmacdonald · 2026-02-24T17:15:28Z

src/i18n/languageManager.js

+ * @param {string} languageCode - The selected language locale code (e.g., 'en', 'es', 'ar').
+ *                               Should be a valid ISO language code supported by the platform.


Please give more specific examples of what these locale codes are like (e.g. fr-ca ?) because the platform has at least two separate lists of locale codes, with different formats, and browsers/react-intl tend to use yet a third format (fr-CA part lowercase, part uppercase) that's different than either of the platform's two backend formats.

Also, since this is a brand new file, can you not use TypeScript?

Thanks for pointing out the different formats available in the platform, I check in Django docs (https://docs.djangoproject.com/en/6.0/topics/i18n/translation/) to understand which format apply in this case, it says should work with LANGUAGES, so I will update the example taking that in consideration.

since this is a brand new file, can you not use TypeScript?

I'm not sure what do you refer here, could you help me with a more context?. I understand the comment is JSDoc format.

I'm not sure what do you refer here, could you help me with a more context?. I understand the comment is JSDoc format.

I mean rename this file to languageManager.ts (not .js) and change it like this:

export async function changeUserSessionLanguage( - languageCode, - forceReload = false, - ) { + languageCode: string, + forceReload = false, + ) -> Promise<void> {

etc.

bradenmacdonald · 2026-02-24T17:35:54Z

Architecturally, it makes total sense to me to encapsulate all this functionality into a cohesive API. As for the details of which languages etc, I'll leave that to the others who are discussing it.

Event System Integration: Publishes events when locale changes to allow components to react

I'm not sure we really need an event for locale changes anymore (or ever did)? Because any react-intl components like <FormattedMessage /> will get re-rendered when the locale changes, and any components that use the useIntl() hook will also get re-rendered when the locale changes. If you want to "listen for a locale change event", you essentially only need this code in a component:

const intl = useIntl();
useEffect(() => {
  // This runs after the component first mounts and anytime the locale changes.
}, [intl.locale]);

So, I think it makes sense to continue emitting our custom LOCALE_CHANGED event for backwards compatibility, but maybe we should mark it as deprecated while we're at it, and just use the standard react-intl APIs for achieving the same thing. Or is there some use case I'm missing?

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Ang-m4 force-pushed the afg/change-user-language-preference branch from c87194b to a17955e Compare April 2, 2025 14:08

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feat: add language selector component to header openedx/frontend-component-header#586

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[WIP] refactor: change lang selector logic openedx/frontend-component-footer#493

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[NO MERGE] testing languange selector implementation openedx/frontend-app-learning#1741

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Ang-m4 added 7 commits October 5, 2025 18:14

feat(i18n): add language preference management functionality

42fca2f

fix: force page reload to ensure complete translation application

f0814f7

feat: conditional page reloading and module rename

a5c70f5

refactor(i18n): move language preference functions to languageApi module

2a3be05

test(i18n): add unit tests for languageApi and languageManager functions

b63d4ee

feat(i18n): add getSupportedLocales function

837ef56

feat(i18n): update user preferences function

d6d1cd7

Ang-m4 force-pushed the afg/change-user-language-preference branch from c2d269c to 133b230 Compare October 6, 2025 01:57

feat(i18n): update getSupportedLocaleList function

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andrey-canon mentioned this pull request Oct 7, 2025

feat(i18n): add language preference management functionality nelc/frontend-platform#14

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fix: remove client-side cookie setting to prevent duplication

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	export async function updateUserPreferences(username, preferenceData) {
	export async function updateAuthenticatedUserPreferences(preferenceData) {

		* @param {string} languageCode - The selected language locale code (e.g., 'en', 'es', 'ar').
		* Should be a valid ISO language code supported by the platform.

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Ang-m4 commented Apr 1, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Language Management Module

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New Functions

API Usage

Related Work

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