Htykuut

Relative newbie; forgive me if my etiquette and form here aren't great. I'm open to feedback.

I have used create-react-native-app to create an application using PouchDB (which I believe ultimately uses AsyncStorage) to store a list of "items" (basically).

Within a TabNavigator (main app) I have a StackNavigator ("List screen") for the relevant portion of the app. It looks to the DB and queries for the items and then I .map() over each returned record to generate custom ListView-like components dynamically. If there are no records, it alternately displays a prompt telling the user so. In either case, there is an "Add Item" TouchableOpacity that takes them to a screen where they an add a new item (for which they are taken to an "Add" screen).

When navigating back from the "Add" screen I'm using a pattern discussed quite a bit here on SO in which I've passed a "refresh" function as a navigation param. Once the user uses a button on the "Add" screen to "save" the changes, it then does a db.post() and adds them item, runs the "refresh" function on the "List screen" and then navigates back like so:

<TouchableOpacity

           style={styles.myButton}

           onPress={() => {

              if (this.state.itemBrand == '') {

                Alert.alert(

                'Missing Information',

                'Please be sure to select a Brand',

                  [

                    {text: 'OK', onPress: () => 

                    console.log('OK pressed on AddItemScreen')},

                  ],

                { cancelable: false }

                )

              } else {

                this.createItem();

                this.props.navigation.state.params.onGoBack();

                this.props.navigation.navigate('ItemsScreen');

               }

              }

            } 

         >

And all of this works fine. The "refresh" function (passed as onGoBack param) works fine... for this screen. The database is called with the query, the new entry is found and the components for the item renders up like a charm.

Each of the rendered ListItem-like components on the "List screen" contains a react-native-slideout with an "Edit" option. An onPress for these will send the user to an "Item Details" screen, and the selected item's _id from PouchDB is passed as a prop to the "Item Details" screen where loadItem() runs in componentDidMount and does a db.get(id) in the database module. Additional details are shown from a list of "events" property for that _id (which are objects, in an array) which render out into another bunch of ListItem-like components.

The problem arises when either choose to "Add" an event to the list for the item... or Delete it (using another function via [another] slideout for these items. There is a similar backward navigation, called in the same form as above after either of the two functions is called from the "Add Event" screen, this being the "Add" example:

async createEvent() {

    var eventData = {

      eventName: this.state.eventName.trim(),

      eventSponsor: this.state.eventSponsor.trim(),

      eventDate: this.state.eventDate,

      eventJudge: this.state.eventJudge.trim(),

      eventStandings: this.state.eventStandings.trim(),

      eventPointsEarned: parseInt(this.state.eventPointsEarned.trim()),

    };



    var key = this.key;

    var rev = this.rev;

    await db.createEvent(key, rev, eventData);

  }

which calls my "db_ops" module function:

exports.createEvent = function (id, rev, eventData) { 

console.log('You called db.createEvent()');

db.get(id)

.then(function(doc) {

    var arrWork = doc.events; //assign array of events to working variable

    console.log('arrWork is first assigned: ' + arrWork);

    arrWork.push(eventData);

    console.log('then, arrWork was pushed and became: ' + arrWork);



    var arrEvents = arrWork.sort((a,b)=>{

        var dateA = new Date(a.eventDate), dateB = new Date(b.eventDate);

         return b.eventDate - a.eventDate;

     })

    doc.events = arrEvents;



    return db.put(doc);

})

.then((response) => {

    console.log("db.createEvent() response was:n" + 

    JSON.stringify(response));

})

.catch(function(err){

    console.log("Error in db.createEvent():n" + err);

});

} 

After which the "Add Event" screen's button fires the above in similar sequence to the first, just before navigating back:

this.createEvent();

this.props.navigation.state.params.onGoBack();

this.props.navigation.navigate('ItemsDetails');

The "refresh" function looks like so (also called in componentDidMount):

    loadItem() {

      console.log('Someone called loadItem() with this.itemID of ' + this.itemID);

  var id = this.itemID;

  let totalWon = 0;

  db.loadItem(id)

  .then((item) => {

    console.log('[LOAD ITEM] got back data of:n' + JSON.stringify(item));

    this.setState({objItem: item, events: item.events});



    if (this.state.events.length != 0) { this.setState({itemLoaded: true});

      this.state.events.map(function(event) { 

        totalWon += parseInt(event.eventPointsEarned);

        console.log('totalWon is ' + totalWon + ' with ' +

        event.eventPointsEarned + ' having been added.');

      });

    };

    this.setState({totalWon: totalWon});

  })

  .catch((err) => { 

    console.log('db.loadItem() error: ' + err);

    this.setState({itemLoaded: false});

  });    

 }

I'm at a loss for why the List Screen refreshes when I add an item... but not when I'm doing other async db operations with PouchDB in what I think is similar fashion to modify the object containing the "event" information and then heading back to the Item Details screen.

Am I screwing up with Promise chain someplace? Neglecting behavior of the StackNavigator when navigating deeper?

The only other difference being that I'm manipulating the array in the db function in the non-working case, whereas the others I'm merely creating/posting or deleting/removing the record, etc. before going back to update state on the prior screen.

Edit to add, as per comments, going back to "List screen" and the opening "Item Details" does pull the database data and correctly shows that the update was made.

Further checking I've done also revealed that the console.log in createEvent() to print the response to the db call isn't logging until after some of the other dynamic rendering methods are getting called on the "Item Details" screen. So it seems as though the prior screen is doing the get() that loadItem() calls before the Promise chain in createEvent() is resolving. Whether the larger issue is due to state management is still unclear -- though it would make sense in some respects -- to me as this could be happening regardless of whether I've called my onGoBack() function.

Edit/bump: I’ve tried to put async/await to use in various places in both the db_ops module on the db.get() and the component-side loadItem() which calls it. There’s something in the timing of these that just doesn’t jive and I am just totally stuck here. Aside from trying out redux (which I think is overkill in this particular case), any ideas?

There is nothing to do with PDB or navigation, it's about how you manage outer changes in your depending (already mounted in Navigator since they are in history - it's important to understand - so componentDidMount isn't enough) components. If you don't use global state redux-alike management (as I do) the only way to let know depending component that it should update is passing corresponding props and checking if they were changed.
Like so:

    //root.js

    refreshEvents = ()=> { //pass it to DeleteView via screenProps

        this.setState({time2refreshEvents: +new Date()}) //pass time2refreshEvents to EventList via screenProps

      }



    //DeleteView.js

    //delete button... 

onPress={db.deleteThing(thingID).then(()=> this.props.screenProps.refreshEvents())}



    //EventList.js

    ...

    constructor(props) {

        super(props);

        this.state = {

          events: ,

          noEvents: false,

          ready: false,

          time2refreshEvents: this.props.screenProps.time2refreshEvents,

          }

      }



    static getDerivedStateFromProps(nextProps, currentState) {

        if (nextProps.screenProps.time2refreshEvents  !== currentState.time2refreshEvents ) {

          return {time2refreshEvents : nextProps.screenProps.time2refreshEvents }

        } else {

          return null

        }

      }



    componentDidMount() {

        this._getEvents()

      }



    componentDidUpdate(prevProps, prevState) {

        if (this.state.time2refreshEvents !== prevState.time2refreshEvents) {

          this._getEvents()

        }

      }



    _getEvents = ()=> {

    //do stuff querying db and updating your list with actual data

    }