Device > Channels > Import > The "Task finished" snackbar is never shown

[pcenov]

Observed behavior

This is a follow-up to #12946 - The "Task finished" snackbar is never shown after successfully importing/exporting or deleting a channel. This is valid for both Kolibri 0.17 and 0.18.

Expected behavior

Should be investigated why is this snackbar not being displayed and if possible it should be restored.

Steps to reproduce the issue

1. Install the latest develop build or Kolibri 0.17.4
2. Go to Device > Channels > Import and import/export/delete a channel
3. Observe that only the "Task started" snackbar is displayed

Usage Details

Windows 11, Ubuntu 22 - Chrome

[pcenov]

@rtibbles

[rtibbles]

Thanks @pcenov

[shruti862]

@rtibbles @pcenov Is this issue open to work upon??

[rtibbles]

Yes - ensuring that the task finished snackbar properly displays when a task finishes would be what is needed!

[shruti862]

@rtibbles Could you please assign the issue to me? I would like to give it a try.

[ananyakaligal]

@rtibbles @pcenov I would also like to give it a try, could you please assign me this?

[LianaHarris360]

Thank you both for your willingness to help with this! We only need one person to handle it at a time, and since @shruti862 asked first, I'll assign it to them.

[karankoder]

Hi @LianaHarris360 , I noticed that this issue is still open, and it seems @shruti862 is not actively working on it. Could you please assign this issue to me? I'd like to take it up

[LianaHarris360]

Hi @karankoder, we'll wait another week since the holidays are coming to an end. If there's no update by then, I'll hand it over to @ananyakaligal if they are still interested, if not I'll assign to you. @shruti862, can you let me know if you will be working on this?

[shruti862]

@LianaHarris360 Yes, I am working on it; I have already inspected the cause of issue but due to the holidays I thought to share afterwards ,By tonight I will share my work.

[LianaHarris360]

Thanks for the update and your thoughtfulness in waiting until after the holidays to share @shruti862! It's great that you're making progress, there's no rush to share it by tonight :)

[shruti862]

@rtibbles @pcenov ,After inspecting the issue I noticed that watcher on computed property (watchedTaskHasFinished ) is not being triggered in taskNotificationMixin.js file due to which createTaskFinishedSnackbar() method is not called leading to no display of finished Snackbar. But I was unable to inspect the cause of watcher not being triggered because both watchedTaskId and watchedTaskHasFinished values are changing on task starting and on ending..Could you please suggest me something which can help me figure out the problem

computed: {
    watchedTaskId() {
      return this.$store.state.manageContent.watchedTaskId;
    },
    watchedTaskHasFinished() {
      // Should switch between null and the taskIds, and can be watched
      // by component to trigger side effects when a task finishes.
      return this.$store.getters['manageContent/taskFinished'](this.watchedTaskId);
    },
  },
  watch: {
    watchedTaskHasFinished(val) {
        if (val && val === this.watchedTaskId) {
          if (this.showSnackbarWhenTaskHasFinished) {
            this.createTaskFinishedSnackbar();
          }
          if (typeof this.onWatchedTaskFinished === 'function') {
            this.onWatchedTaskFinished();
          }
        }
     
    },
  },

[rtibbles]

Hrm, that is tricky - and this watcher is never called at all?

  watch: {
    watchedTaskHasFinished(val) {
        if (val && val === this.watchedTaskId) {
          if (this.showSnackbarWhenTaskHasFinished) {
            this.createTaskFinishedSnackbar();
          }
          if (typeof this.onWatchedTaskFinished === 'function') {
            this.onWatchedTaskFinished();
          }
        }
     
    },
  },

Or is it called only with a falsy value so it doesn't get past the if statement? Or a value that isn't equal to this.watchedTaskId?

[shruti862]

@rtibbles, According to my finding watchers is never called, But when I tried to call it on initial render by using immediate:true , it does triggered because at that time it is not dependent on change in a computed property.
watchedTaskId computed property is working fine ,I think the issue resides in taskFinished getter which is being called in watchedTaskHasFinished computed property. But again unable to figure it out .

[AlexVelezLl]

Hey @shruti862! Are we sure that this taskNotificationMixin is being used in that page? I just added a console.log on mounted, but didnt see any outputs in the console. Can you double check if that mixin is used in the manage tasks page?

[shruti862]

Hey @AlexVelezLl After inspecting using vue devtool I found that in manageChannelContentPage, on clicking delete button handleDeleteSubmit method evoke which has this.onTaskSuccess method which displays 'Task started' Snackbar through notifyAndWatchTask(task)

 handleDeleteSubmit({ deleteEverywhere }) {
        this.beforeTask();
        this.startDeleteTask({
          deleteEverywhere,
          channelId: this.channelId,
          channelName: this.channel.name,
          included: this.selections.included,
          excluded: this.selections.excluded,
        }).then(this.onTaskSuccess, this.onTaskFailure);
      },
      handleExportSubmit({ driveId }) {
        this.beforeTask();
        this.startExportTask({
          driveId,
          channelId: this.channelId,
          channelName: this.channel.name,
          included: this.selections.included,
          excluded: this.selections.excluded,
        }).then(this.onTaskSuccess, this.onTaskFailure);
      },
      beforeTask() {
        this.closeModal();
        this.bottomBarDisabled = true;
      },
      onTaskSuccess(task) {
        this.bottomBarDisabled = false;
        this.watchedTaskType = task.type;
        this.notifyAndWatchTask(task);
      },

and it also have this onWatchedTaskFinished() method which is supposed to be used by taskNotificationMixin to display 'Task Finished' Snackbar

/**
       * @public
       * Used by the taskNotificationMixin to handle the completion of the task
       */
      onWatchedTaskFinished() {
        // clear out the nodeCache
        this.nodeCache = {};
        // clear out selections
        this.$store.commit('manageContent/wizard/RESET_NODE_LISTS');
        // refresh the data on this page. if the entire channel ends up
        // being deleted, then redirect to upper page
        this.fetchPageData(this.channelId)
          .then(this.setUpPage)
          .catch(error => {
            // If entire channel is deleted, redirect
            if (error.response.status === 404) {
              this.$router.replace({ name: PageNames.MANAGE_CONTENT_PAGE });
            } else {
              this.$store.dispatch('handleApiError', { error });
            }
          });
      },

[shruti862]

@AlexVelezLl I found nothing revelant in ManageTaskPage which is responsible for displaying Snackbar

[rtibbles]

It seems reasonable that there may be an issue in the reactivity of taskFinished getter, based on your observations. My guess would be is that it is not updating when the underlying vuex state updates.

I would look and see if watching either the task itself, or the task's status triggers a watcher? Then we can just check the status in the watcher to see if it has finished and trigger the snackbar based on that?

[shruti862]

Hey @rtibbles ,When I tried to have tasks computed property, it is not updating with finished tasks, it remains a empty array is it due to reactivity issues? In Vuex store taskList is being updated but not reflecting changes in tasks computed property

computed: {
    watchedTaskId() {
      return this.$store.state.manageContent.watchedTaskId;
    },
    tasks() {
      return this.$store.state.manageContent.taskList;
    },
  },

[shruti862]

Hey @rtibbles , any suggestions on resolving this reactivity issue would be appreciated so I can start working on it. If there are no updates or if someone else is better suited to take it up, feel free to unassign me so others can contribute. Thanks!

[rtibbles]

So, it seems the way that the taskList vuex state is being updated is not triggering reactivity. What is the vuex mutation that is updating it? Where is it being updated?

[shruti862]

Hey @rtibbles , in kolibri/plugins/device/assets/src/modules/manageContent/index.js file I found mutation that is updating taskList

function defaultState() {
  return {
    channelList: [],
    channelListLoading: false,
    taskList: [],
    watchedTaskId: null,
  };
}

export default {
  namespaced: true,
  state: defaultState,
  mutations: {
    SET_STATE(state, payload) {
      Object.assign(state, payload);
    },
    RESET_STATE(state) {
      Object.assign(state, defaultState());
    },
    SET_CHANNEL_LIST(state, channelList) {
      state.channelList = [...channelList];
    },
    SET_CHANNEL_LIST_LOADING(state, isLoading) {
      state.channelListLoading = isLoading;
    },
    SET_TASK_LIST(state, taskList) {
      state.taskList = [...taskList];
    },
    SET_WATCHED_TASK_ID(state, taskId) {
      state.watchedTaskId = taskId;
    },

[rtibbles]

Hrm, that does look like it shouldn't be falling foul of any of the usual reactive gotchas.

Can you try using the mapState helper function from vuex to define the tasks computed property instead of directly accessing the store to see if that makes a difference?

See here for guidance: https://vuex.vuejs.org/guide/state.html#the-mapstate-helper (looking at how it is used elsewhere in Kolibri will also help!)

[shruti862]

Hey @rtibbles, Thank you for your suggestion. I will try this approach as well and provide you with updates soon.

[shruti862]

Hey @rtibbles, I tried your suggestion
Code changes:

 computed: {
    ...mapState('manageContent', {
      taskList: state => state.taskList,
      watchedTaskId: state => state.watchedTaskId
    }),
  },

Before deleting resources computed properties were:

After deleting resources, only watchedTaskId is getting updated ( as seen under vuex binding in vue-devtools ),taskList still remains empty array:

[MisRob]

Hi @shruti862, would you be able to debug a bit deeper around what's the reactivity issue around taskList? Maybe there is a place in code that doesn't update the array in a way that breaks the reactivity chain? https://v2.vuejs.org/v2/guide/reactivity.html#Change-Detection-Caveats

[MisRob]

If this doesn't help then I'd recommend you track step by step places executed in code that (1) set and (2) retrieve the task list and see at what point exactly the mismatch begins

[shruti862]

@MisRob Thank you for your suggestions I will try to debug it deeper and will provide updates soon.