Issue with 'reading' global variable with OnVisible of secondary start screen.

[jnickell]

I have a 3 screen app and have setup deep linking to the "third screen" based on a URL parameter. Pretty reliably (near 100% of the time) if a user utilizes the deeplink for their "first access" to the app, the OnVisible attribute for the third screen reads the global variable set by App OnStart as blank. However, I've added a debug text box to the screen and it 'clearly' shows the Global Variable value I expect. If I add a button to the screen that basically re-runs the code in OnVisibile everything functions as I expect. 

The app is backed by a Sharepoint List if this matters.

The code that I think matters is:

App: OnStart:

...
  If (Param("TargetScreen") = "Edit", 
    Set(SelectedItemID, Value(Param("NCRID")))
)

App: StartScreen

If (Param("TargetScreen") = "Edit", 
    NCREntryScreen,
    Browse_All )

NCREntryScreen: Onvisible

If(IsBlank(SelectedItemID),
    // We are creating a new NCR
    UpdateContext({CurrentNCRID: ""}),
    // We are working with an existing NCR
    UpdateContext({CurrentNCRID: 
        LookUp([@NCRs],
            ID = SelectedItemID,
            Title
        )
        }
    )
)

My Diagonistic Text Label: Text value is:

Concatenate("SelectedItemID: ", SelectedItemID, " NCRID: ", CurrentNCRID)

Re-try button: OnSelect

If(IsBlank(SelectedItemID),
    UpdateContext({CurrentNCRID:First(AdHocNCRID).Title}),
    UpdateContext({CurrentNCRID: 
        LookUp([@NCRs],
            ID = SelectedItemID,
            Title
        )
        }
    )
)

If I access the app with a url like the one below:

https://apps.powerapps.com/play/<APPID>?NCRID=542&TargetScreen=Edit

I am correctly routed to the desired screen, but the Text Label value shows: "SelectedItemID: 542 NCRID: "

Usually if I go to re-paste the URL in the browser it will render correctly like this: "SelectedItemID: 542 NCRID: 10396", right at the moment as I'm posting this, it's not behaving like this, but I'm not sure if my testing broke a piece of the code.

Is this because OnVisible is running before something's getting fully set? Would appreciate any insight.

[BCBuizer · Accepted solution]

Hi @jnickell ,

I think you have "Use non-blocking OnStart rule" turned on in the Upcoming features: 

With this enables it can be that your CurrentNRID variable is populated before Selecteditem was, causing it to be blank.

I'd try turning this off to confirm and as a quick fix.

Ultimately, however, I would reconsider using two variables. I feel that using a single global variable would give you all you need, reduce complexity and take care of issues like these.

[WarrenBelz]

Hi @jnickell ,

The issue here I believe is that StartScreen runs before OnStart. The easiest solution is to put the OnStart code you have posted OnVisible of the relevant screen and it will work fine.

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[jnickell]

I didn't know I had the non-blocking piece on, but I did. 
RE: the two variables, I made this app a couple of years ago and I think at the time Context Variables were needed for some piece of what I was doing in the app, though at this point I can't say for sure. 

I'll test out disabling that rule tomorrow. 

[jnickell]

I'll give this a shot too if the OnStart rule doesn't give me a workaround

[jnickell]

@BCBuizer Disabling the async app start seems to address the issue. I'll take this as the solution. Didn't realize that was a setting, thank you for brining it to my attention.

@WarrenBelz Thanks for your guidance as well. I didn't try that approach but it seems like it could work, but would wind up duplicating code that I'd rather not for now.