Fix quickly switching notification filters resulting in empty or incorrect list (#18960)

app/javascript/mastodon/actions/notifications.js

@@ -141,13 +141,13 @@ const excludeTypesFromFilter = filter => {
 
 const noOp = () => {};
 
-export function expandNotifications({ maxId } = {}, done = noOp) {
+export function expandNotifications({ maxId, forceLoad } = {}, done = noOp) {
   return (dispatch, getState) => {
     const activeFilter = getState().getIn(['settings', 'notifications', 'quickFilter', 'active']);
     const notifications = getState().get('notifications');
     const isLoadingMore = !!maxId;
 
-    if (notifications.get('isLoading')) {
+    if (notifications.get('isLoading') && !forceLoad) {
       done();
       return;
     }
@@ -243,7 +243,7 @@ export function setFilter (filterType) {
       path: ['notifications', 'quickFilter', 'active'],
       value: filterType,
     });
-    dispatch(expandNotifications());
+    dispatch(expandNotifications({ forceLoad: true }));
     dispatch(saveSettings());
   };
 };

app/javascript/mastodon/reducers/notifications.js

@@ -41,7 +41,7 @@ const initialState = ImmutableMap({
   lastReadId: '0',
   readMarkerId: '0',
   isTabVisible: true,
-  isLoading: false,
+  isLoading: 0,
   browserSupport: false,
   browserPermission: 'default',
 });
@@ -115,7 +115,7 @@ const expandNormalizedNotifications = (state, notifications, next, isLoadingRece
       }
     }
 
-    mutable.set('isLoading', false);
+    mutable.update('isLoading', (nbLoading) => nbLoading - 1);
   });
 };
 
@@ -214,9 +214,9 @@ export default function notifications(state = initialState, action) {
   case NOTIFICATIONS_LOAD_PENDING:
     return state.update('items', list => state.get('pendingItems').concat(list.take(40))).set('pendingItems', ImmutableList()).set('unread', 0);
   case NOTIFICATIONS_EXPAND_REQUEST:
-    return state.set('isLoading', true);
+    return state.update('isLoading', (nbLoading) => nbLoading + 1);
   case NOTIFICATIONS_EXPAND_FAIL:
-    return state.set('isLoading', false);
+    return state.update('isLoading', (nbLoading) => nbLoading - 1);
   case NOTIFICATIONS_FILTER_SET:
     return state.set('items', ImmutableList()).set('pendingItems', ImmutableList()).set('hasMore', true);
   case NOTIFICATIONS_SCROLL_TOP: