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

Thanks for the pull request, @Ang-m4!

This repository is currently maintained by @openedx/committers-frontend.

Once you've gone through the following steps feel free to tag them in a comment and let them know that your changes are ready for engineering review.

🔘 Get product approval

If you haven't already, check this list to see if your contribution needs to go through the product review process.

If it does, you'll need to submit a product proposal for your contribution, and have it reviewed by the Product Working Group.
- This process (including the steps you'll need to take) is documented here.
If it doesn't, simply proceed with the next step.

🔘 Provide context

To help your reviewers and other members of the community understand the purpose and larger context of your changes, feel free to add as much of the following information to the PR description as you can:

Dependencies

This PR must be merged before / after / at the same time as ...
Blockers

This PR is waiting for OEP-1234 to be accepted.
Timeline information

This PR must be merged by XX date because ...
Partner information

This is for a course on edx.org.
Supporting documentation
Relevant Open edX discussion forum threads

🔘 Submit a signed contributor agreement (CLA)

⚠️ We ask all contributors to the Open edX project to submit a signed contributor agreement or indicate their institutional affiliation.
Please see the CONTRIBUTING file for more information.

If you've signed an agreement in the past, you may need to re-sign.
See The New Home of the Open edX Codebase for details.

Once you've signed the CLA, please allow 1 business day for it to be processed.
After this time, you can re-run the CLA check by adding a comment below that you have signed it.
If the CLA check continues to fail, you can tag the @openedx/cla-problems team in a comment for further assistance.

🔘 Get a green build

If one or more checks are failing, continue working on your changes until this is no longer the case and your build turns green.

Details

Where can I find more information?

If you'd like to get more details on all aspects of the review process for open source pull requests (OSPRs), check out the following resources:

When can I expect my changes to be merged?

Our goal is to get community contributions seen and reviewed as efficiently as possible.

However, the amount of time that it takes to review and merge a PR can vary significantly based on factors such as:

The size and impact of the changes that it introduces
The need for product review
Maintenance status of the parent repository

💡 As a result it may take up to several weeks or months to complete a review and merge your PR.

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.

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 98.30508% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 88.36%. Comparing base (cf61627) to head (0abefe9).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
src/i18n/lib.ts	96.42%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #786      +/-   ##
==========================================
+ Coverage   87.86%   88.36%   +0.50%     
==========================================
  Files          50       52       +2     
  Lines        1483     1556      +73     
  Branches      297      306       +9     
==========================================
+ Hits         1303     1375      +72     
- Misses        169      170       +1     
  Partials       11       11

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

dcoa · 2025-06-19T12:41:14Z

+  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

+  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

+ * @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

+  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?

Update: after reviewing more carefully the Django templates for comparison and considering the message above I updated the endpoint to use update_language

My apologize if took me some time to implement this change. I look forward to any comment.

arbrandes · 2025-09-19T15:31:09Z

+  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

+  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?

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

+ * @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.

I just want to confirm, it is TypeScript supported in frontend-platform? I don't see any reference in main so I wonder if might need that first.

[Update]: I create this PR #868 to add minimal configuration for babel, could you help me with the review? :)

Left a review with a change request with what seems like a minor oversight.

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?

gabrieldamours · 2026-06-24T15:22:12Z

Hi @arbrandes! Quick check-in here — what are the next steps?

arbrandes

As I just mentioned to @bradenmacdonald in another issue, I think that at this point, anything major such as this should land in frontend-base first. I'm marking this review as "request changes" precisely so we can do this before merging anything here.

Why? Because frontend-base is the future, and we'll have to decide what the right path is there first. Once we know what the future looks like (do we depend on an edx-platform API or not? What can users do? What can sysadmins do?), we can then decide to backport it, or not.

So, @gabrieldamours, and @dcoa, the next step is: let's get this - and the accompanying UI - merged into frontend-base before anything else.

arbrandes · 2026-08-07T17:50:14Z

This is the new epic:

openedx/public-engineering#558

TLDR: frontend-base already has most of the functionality. We just need to agree on everything (such as moving or copying the selector to the header - it's currently in the footer - or what the selector looks like, and of course, finally, if we're doing away with Darklang entirely).

felipemontoya · 2026-08-07T18:36:17Z

Hey Adolfo, while I understand the tech story I'd like to highlight the product story. 3 years ago a customer asked for this. We told them it's better to go through the community. After 2 major refactors and building this as a second PR that supposedly contained all the learnings from the first 2 years of discussion, the result is that this no longer will be accepted as is and instead requires to go through a third major refactor.

It's difficult to sustain to this costumer that going through the community is a better option. And they have told me so. 3 years still no solution for a language selector through the community. That is the message they got.

Sorry to publish my frustrations specificly to you, but this issue had been a hard one.

The original pr author even left our company in the meantime.

arbrandes · 2026-08-07T20:51:00Z

@felipemontoya, I hear you. We're trying to get better at addressing these ideas. I'm open to having a retro-style discussion about this one in particular, so we can try to avoid whatever issues it ran into.

In such a discussion, I think I'd pin it on uncertainties about a) UX, and b) implementation. These uncertainties are, to this day, not resolved. It is hard to approve PRs if we can't agree on what the end result should be.

arbrandes · 2026-08-07T20:51:39Z

The good news is that I personally want to get this resolved/approved/merged for Willow. I'd love your help!

openedx-webhooks added the open-source-contribution PR author is not from Axim or 2U label Apr 1, 2025

openedx-webhooks added this to Contributions Apr 1, 2025

github-project-automation Bot moved this to Needs Triage in Contributions Apr 1, 2025

mphilbrick211 moved this from Needs Triage to Waiting on Author in Contributions Apr 1, 2025

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

Ang-m4 mentioned this pull request Apr 2, 2025

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

Open

Ang-m4 marked this pull request as ready for review April 3, 2025 13:04

Ang-m4 mentioned this pull request Apr 3, 2025

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

Draft

dcoa requested a review from arbrandes May 29, 2025 19:51

arbrandes requested changes Jun 5, 2025

View reviewed changes

Comment thread src/i18n/LanguageManager.js Outdated

dcoa reviewed Jun 13, 2025

View reviewed changes

Comment thread src/i18n/LanguageManager.js Outdated

Ang-m4 force-pushed the afg/change-user-language-preference branch from 1e1f82c to d83e228 Compare June 18, 2025 19:25

dcoa reviewed Jun 19, 2025

View reviewed changes

dcoa mentioned this pull request Jun 22, 2025

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

Closed

Ang-m4 requested a review from arbrandes June 25, 2025 15:56

mphilbrick211 moved this from Waiting on Author to Ready for Review in Contributions Sep 16, 2025

arbrandes requested changes Sep 19, 2025

View reviewed changes

Ang-m4 force-pushed the afg/change-user-language-preference branch 2 times, most recently from 133b230 to b0b7b34 Compare October 6, 2025 02:01

Ang-m4 requested a review from dcoa October 6, 2025 14:02

andrey-canon mentioned this pull request Oct 7, 2025

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

Merged

dcoa requested a review from arbrandes October 8, 2025 12:53

dcoa approved these changes Oct 8, 2025

View reviewed changes

bradenmacdonald reviewed Feb 24, 2026

View reviewed changes

mphilbrick211 added the waiting on author PR author needs to resolve review requests, answer questions, fix tests, etc. label Apr 6, 2026

dcoa force-pushed the afg/change-user-language-preference branch 2 times, most recently from 82ff56c to 4fb83f9 Compare April 9, 2026 04:54

mphilbrick211 removed the waiting on author PR author needs to resolve review requests, answer questions, fix tests, etc. label Apr 9, 2026

itsjeyd added the waiting for eng review PR is ready for review. Review and merge it, or suggest changes. label Jun 25, 2026

Ang-m4 and others added 10 commits July 2, 2026 11:34

feat(i18n): add language preference management functionality

8cf5bec

fix: force page reload to ensure complete translation application

57c87ae

feat: conditional page reloading and module rename

78c9741

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

a67e6ef

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

c058589

feat(i18n): add getSupportedLocales function

e25e022

feat(i18n): update user preferences function

b13c5c2

feat(i18n): update getSupportedLocaleList function

7498e40

fix: remove client-side cookie setting to prevent duplication

8904b30

refactor: implement typescript

633d5b6

dcoa force-pushed the afg/change-user-language-preference branch from 4fb83f9 to 633d5b6 Compare July 2, 2026 01:56

refactor: use lang_pref endpoint for setting the cookie

0abefe9

dcoa force-pushed the afg/change-user-language-preference branch from 29b4d94 to 0abefe9 Compare July 2, 2026 06:13

dcoa requested a review from arbrandes July 2, 2026 06:15

arbrandes requested changes Aug 7, 2026

View reviewed changes

This was referenced Aug 7, 2026

Allow users to change the site language from anywhere in the UI openedx/public-engineering#558

Open

Make site language switching a supported runtime API openedx/frontend-base#283

Open

bradenmacdonald mentioned this pull request Aug 7, 2026

Re-export IntlShape from the runtime barrel openedx/frontend-base#280

Open

	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.

Uh oh!

Conversation

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

Uh oh!

Language Management Module

Description

Key Features

Implementation Details

New Functions

API Usage

Related Work

Uh oh!

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

Uh oh!

Uh oh!

arbrandes left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

dcoa commented Jun 13, 2025

Uh oh!

codecov Bot commented Jun 18, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Ang-m4 commented Jun 25, 2025

Uh oh!

dcoa commented Aug 25, 2025

Uh oh!

felipemontoya commented Sep 3, 2025

Uh oh!

arbrandes left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

dcoa Jul 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

dcoa commented Oct 8, 2025

Uh oh!

bradenmacdonald Feb 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

dcoa Mar 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

dcoa Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Ang-m4 commented Apr 1, 2025 •

edited

Loading

openedx-webhooks commented Apr 1, 2025 •

edited

Loading

codecov Bot commented Jun 18, 2025 •

edited

Loading

dcoa Jul 2, 2026 •

edited

Loading

bradenmacdonald Feb 24, 2026 •

edited

Loading

dcoa Mar 2, 2026 •

edited

Loading

dcoa Mar 12, 2026 •

edited

Loading

arbrandes left a comment •

edited

Loading

arbrandes commented Aug 7, 2026 •

edited

Loading

felipemontoya commented Aug 7, 2026 •

edited

Loading