From ae6397ea322f7fc569ee9145420792b6494f9503 Mon Sep 17 00:00:00 2001
From: Kshitij Sobti <kshitij@sobti.in>
Date: Fri, 24 Jun 2022 08:56:08 +0000
Subject: [PATCH] fix: filtering posts in a topic doesn't work when filtered
 results are empty (#203)

A list of all posts in a topic is stored in an object for quick lookup. This is used when switching between topics to get the list of posts in that topic. When filters change the list of posts in a topics is updated and this is picked up by the UI. If changing filters when browsing a topic results in an empty result, this would cause the original list of topics for that topic to be retained, causing the filter to simply not apply. This commit fixes that by resetting the post list in that case.
---
 src/discussions/posts/data/api.js    |  1 +
 src/discussions/posts/data/thunks.js | 10 ++++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/discussions/posts/data/api.js b/src/discussions/posts/data/api.js
index 530edb1d..ed8c6328 100644
--- a/src/discussions/posts/data/api.js
+++ b/src/discussions/posts/data/api.js
@@ -27,6 +27,7 @@ export const coursesApiUrl = `${apiBaseUrl}/api/discussion/v1/courses/`;
  * @param {string} threadType Can be 'discussion' or 'question'.
  * @param {ThreadViewStatus} view Set to "unread" on "unanswered" to filter to only those statuses.
  * @param {boolean} countFlagged If true, abuseFlaggedCount will be available.
+ * @param {number} cohort
  * @returns {Promise<{}>}
  */
 export async function getThreads(
diff --git a/src/discussions/posts/data/thunks.js b/src/discussions/posts/data/thunks.js
index b9883d26..71fc0d94 100644
--- a/src/discussions/posts/data/thunks.js
+++ b/src/discussions/posts/data/thunks.js
@@ -44,9 +44,10 @@ import {
  * Normalises raw data returned by threads API by mapping threads to id and
  * mapping topic ids to threads in them.
  * @param data
+ * @param {[string]?} topicIds
  * @returns {{pagination, threadsById: {}, threadsInTopic: {}, avatars: {}}}
  */
-export function normaliseThreads(data) {
+export function normaliseThreads(data, topicIds = null) {
   const normalized = {};
   let threads;
   if ('results' in data) {
@@ -59,6 +60,11 @@ export function normaliseThreads(data) {
   const threadsById = {};
   let avatars = {};
   const ids = [];
+  if (topicIds) {
+    topicIds.forEach(topicId => {
+      threadsInTopic[topicId] = [];
+    });
+  }
   threads.forEach(
     thread => {
       const { topicId, id } = thread;
@@ -129,7 +135,7 @@ export function fetchThreads(courseId, {
     try {
       dispatch(fetchThreadsRequest({ courseId }));
       const data = await getThreads(courseId, options);
-      const normalisedData = normaliseThreads(camelCaseObject(data));
+      const normalisedData = normaliseThreads(camelCaseObject(data), topicIds);
       dispatch(fetchThreadsSuccess({ ...normalisedData, page, author }));
     } catch (error) {
       if (getHttpErrorStatus(error) === 403) {