Named Formulas Issue: Update cached value when dependent variables change

[aboehm]

When I run my app in the Power Apps preview player, the cached values from named formulas aren't updated when a variable changes on which the formula depends.

I have the following Named Formula in App.Formulas:

CurrentItem = If(
    Not(IsBlank(IdVar)) || IsBlank(SharePointIntegration.Selected) || IsEmpty(SharePointIntegration.Selected);
    Coalesce(
        LookUp(
            [@SPList];
            ID = Coalesce(
                IdVar;
                SharePointIntegration.SelectedListItemID
            )
        );
        Defaults([@SPList])
    );
    SharePointIntegration.Selected
);;

 I have a TextInput control with the following formula in .OnChange:

Set(
    IdVar;
    If(
        Not(IsBlank(Self.Text));
        Int(Self.Text);
        Blank()
    )
);;

Then I have a form where the Item property is set to CurrentItem and the DataSource to [@SPList].

When you change the text in the TextInput control the form will not be updated to display any item from the data source.

When I run this app as a form from the corresponding SharePoint list then the correct selected item will be shown. So, at least the Named Formula will run once on startup or when it is used the first time.

This problem started last week with the Power Apps version 3.23023.

I tried some investigation on my own and found out that the dynamic JavaScript which is created for the _onEntityDataChanged event handler (which is called when a global variable is changed by the Set-function) calls runDependentRules, but it does not include the internal name of Named Formula in the argument list, only all the other "normal" references to the IdVar variable.

I hope this gives a good hint to speed up the release of a fix for this issue.

[aboehm]

Thank you for this hint. It works on another machine and in browser incognito mode on the problem machine.

It also works in the published app in normal browser mode on the problem machine. It only doesn't work in Power Apps preview player when it's not running in browser incognito mode.

So it definitely has something to do how Power Apps editor is caching this dynamically created JavaScript in Edge.

I tried to close Edge and reboot the machine, but to no avail. So I tried nearly everything besides reinstalling Edge to clear this script cache and this can't be the solution.

[jpereira2317]

I understand that changing to incognito and other potential workarounds might have done it. But I think we still want a fix that works for normal users to be able to use. Is that still being worked on? 

[ChrisAtMYB]

Update: It appears that simply wrapping the code in If() statement also solves the issues, regardless of the condition - even when called from App.OnStart and it even works in studio - e.g.:

If(
   1 = 1,
   <code>
)

I've chosen to reformulate my answer entirely as another test revealed that the dependencies in fact are updated even on App.OnStart, but calling the named function either from App.OnStart or Screen.OnVisible is actually the culprit of my issue. Simply setting the dependent variable on App.OnStart and then calling the Named Function from a timer (in my case) works - and it actually also does from a button - however, this only works when playing the app, but does not work in the studio! In the studio I'm only able to properly reset the dependencies of the Named Function by navigating to another screen and then going back.

Also, calling the Named Function from either App.OnStart or Screen.OnVisible still doesn't work when playing the app.

It could appear that you issue might have been fixed(?), but there are still some other issues present.

@aboehm FYI I'm still experiencing the (almost) same issue as you in authoring version 3.23075.7 - however, I've managed to "bypass" the issue by moving the dependencies (declaration of variables as well as call to the Named Function) logic from App.OnStart to a timer with AutoStart = true instead, which in turn seemingly updates the dependencies correctly.

In other words - the issue seems, on my end at least, to be that the variables set on App.OnStart isn't updated properly until either explicitly resetting them on the current page, or at least changing page (and in my case, then navigating back again). 

Still not a viable solution in my opinion, but at least it yields the same user experience as prior, if there's a need to update/develop for production until the issue has been fixed.

[mvkr09552]

Thanks for the update! We will investigate this and have a fix out soon.

[ShantanuP]

@ChrisAtMYB , Can you please share more details about your scenario? Is there a simple repro that we can share which we can use to repro the issue on our end?

[ChrisAtMYB]

@ShantanuP I'm actually no longer able to reproduce the issue, even when rolling back to authoring version 3.23074.17 or 3.23075.16 - but tthanks for coming back.

[ChrisAtMYB]

Hi @ShantanuP ,
Apparently I forgot the original setup that caused the issue, and now I found it again - and the error still persists (authoring version3.23082.17).

The issue is when you ClearCollect() at data source (in my case a Sharepoint List), where the call to the data source is in a Named Formula. Following is what's used to reproduce the issue:

App.OnStart

Set(intNumber, 1);
ClearCollect(
    colData,
    GetData
)

App.Formulas

GetData = Filter('My Sharepoint List', NumberColumn > intNumber);

[ShantanuP]

Thanks, I can see the repro on my end.

[ShantanuP]

Yes, I was able to narrow it down. Is there a reason you are setting a variable in OnStart and using it in Named Formula instead of using the Named Formula itself. I am just trying to understand your setup and scenario.

For example, In App.Formulas expression

intNumber = 1;

GetData = Filter('My Sharepoint List', NumberColumn > intNumber);

Above works fine.  

[ChrisAtMYB]

@ShantanuP  The reason is that the variable can change based on user inputs - in my exact case it’s actually a date that enables users to get data for a period of their choosing.