Global Variable works on Desktop but not on Phone

[MarcBailey]

This post is related to a previous post that I made on on 1-16-18.  The new post was made after extensive testing and will bring more clarity to issue than the original post:

https://powerusers.microsoft.com/t5/General-Discussion/Data-Refresh-Problem-when-Navigating-between-...

The App runs with no problems on my Desktop but on my Mobile Device (IPhone 7) the Global Variable does not update to the Selected Account fast enough.

Problem: On the Mobile Device when selecting the Set and Navigate control for an account from the AccountControl screen - it navigates and populates the data in the AccountLog screen prior to Global Variable being posted.  Therefore, it displays the data from the previous selected account.  If I naviagate back to the AccountControl screen and select another account it displays the previous selected account again which means the Global Variable is getting updated at some point after the AccountLog screen is loaded. 

What's involved in this Scenario - 2 Screens and Code - Uses SharePoint Lists as Datasources:

AccountControl screen - OnSelect:

Set(CurrentAcctID,BrowseGallery1.Selected.ID);Navigate(AccountLog, ScreenTransition.None)

AccountLog screen - Gallery3 - Items:

SortByColumns(Filter(AcctLog,AcctID = Text(CurrentAcctID)),"DateEntered",Ascending)

I have done numerous test including a Collection with the exact same results.

I would appreciate any insight, solution, or workarounds on this matter.

Thanks - Marc

[MarcBailey]

Hi Sienna,

Quick update - I tested the Timer and still have the same problem when running the App on the IPhone.

I have been working with several members of the PowerApps Product Team on another issue which they just provided me with a workaround on it that I can use until it is fixed in the next release.  In my thank you response back to them I included the "Global Variable works on Desktop but not on Phone" issue for their review.  I shared a very simplified App that reflects the issue so they can fully test it.  I will provide you an update when I hear back from them.

Thanks for all of the help - Marc !!

Account Control screenAccount Log screen

[Sienna]

Hi again

I've been trying to reproduce the same error but with no luck. I have tested all possible variants on my iPhone and they all works. But obviously I didn't try sharepoint. My last suggestions would be to reinstall the PA player on your phone try if this will work. I would also try to save the app with different name and try to republish it. And if all this fail then try to create brand new app and test it in small steps and see when it will starting to fail. Good luck and let us know

[MarcBailey]

Hi again,

I have tried all of your suggestions and even created a new App using CDS as the DataSouce and it still displays the previous selected Account in my Global Variable.  I am hoping the PA Product Team will review this and provide a response.  I know they are working on Gallery related issues that are supposed to be corrected in the next release.

Has issue updating variable:

App is running 2.0.750 on my IPhone 7 on iOS 11.2.2 with 235GB available

Works fine using:

App is running 2.0.750 on the Desktop (Edit on the Web) - Windows 8.1 - Chrome or IE browsers

Its definitely a time consuming mystery...

Please let me know if you or anyone else has additional suggestions.

Thanks - Marc...

[Sienna]

I've got only one more.. Have you tried also change a database connected in your gallery to something else then sharepoint?

[MarcBailey]

@CarlosFigueira

@CWesener

@rgruian

Sienna,

I have tried all of your suggestions and even created a new App using CDS as the DataSouce and it still displays the previous selected Account in my Global Variable. 

I have reviewed my settings on my IPhone - definitely think this is a PowerApps issue.

In the meantime I am going to have to use a Temporary Workaround which utilizes two separate OnSelect controls the first Sets the variable (which will update it to the previous ID) without navigating and then the second Sets the variable again (which will update to the previous ID again but will be the Account that user needs selected) with navigation to the AccountLog screen.  See images below:

First ClickSecond Click

[Anorakman]

I've just encountered this exact same issue.  Running the app on a desktop, no problem.  Using it on an iPad, the Global Variable is always one step behind.  I am using the variable to take the ID of a record in a gallery to a new screen where changes can be made to that record.  When the navigation takes place the new screen shows the record from the previously selected record, not the current one.

I have tried blanking the variable before setting it, but the previous value is still the one used when loading the new screen.   The setting of the global variable is marching to the beat of a different drummer.

Any chance of an update on what is happening with this issue?

[Anorakman]

@CarlosFigueira

@CWesener

@rgruian

There is definitely a problem with the way global variables are handled in the PowerApp app in iOS.  The difference between how things work on a pc desktop and on an iPad is stark.

[KroonOfficeSol]

He MarcBailey,

I respond on the main threat because off all nonsense solutions mentioned earlier (sorry for saying so). The behaviour you're experience is quit logic in my opinion (when you really thing about it a little longer). It is simple caused by the fact that a screen does nothing when not visible (for performance reasons), which means that on visible it will first go out and update the data source t screen and the controls rely on to be able to show the right content. Meanwile it will do nothing, giving the former data to be visible. Looks to me like normal behaviour in every way.

The behaviour is simple to overcome. Try this:

1.  Set a local variable in the navigation() formula and set this to equal the global variable. Like:

   Navigate(MyScreen, None, {MyLocalVariable: MyGlobalVariable})

2. Connect the Gallery to the local variable by using a lookup() function in the Item property, like

   LookUp(DataSource, MyID = MyLocalVariable)

3. Reset the local variable on leaving the screen (so in the OnHidden Property), Like

   UpdateContext({MyLocalVariable:Blank()})

What the 3 line does is basically clear the gallery, simple because a blank() in the condition is no match to an existing record. So if you go to the screen in design the Gallery will be empty therefor. My good practice btw is to reset all the variables and temperal collections always when leaving the screen (only off course when a go up in my hirarchie, so not when I drill down to a deeper detail level (hope this makes sense) 

Still you have to wait for the gallery to update the connected data source, but the gallery will be empty (so white) or not visible till this is finished and the lookup is executed.

Btw I made a youtube video serie which explains these concepts in great detail with an example on a re-usable screen. If you want to learn on this topic here is the link: PowerApps - Re-Use Screens 

Btw 2: Storing your datasource in a collection can make the load time off the screen faster (which will mean that the record is shown faster), this is because there is no call needed to the datasource to update (the collection is already in place and locally available). But there are some side effects which can be tricky depending on the data you're using in the gallery.

Hope this helps.

[Anorakman]

Here is a description of an app that demostrates the problem so it can be replicated.

Screen1 contains a gallery of records several records.  Each record has a unique ID field called RecordID.  There is a button in the gallery used to navigate to Screen2 and set the value of global variable SelectedItem to the ID of the record in the gallery:

• Gallery Button OnSelect = Set(SelectedItem,GalleryScreen1.Selected.RecordID); Navigate(Screen2, None)

Screen 2 contains 2 labels:

• Label1.Text = SelectedItem
• Label2.Text = GalleryScreen1.Selected.RecordID

For ease of demo add a button to Screen 2 with OnSelect = Back()

Now try the app in PowerApps in a browser.  Result: Label1 shows same value as Label2 no matter which record is selected in the gallery on Screen1.

Try the same app in PowerApps in iOS. Result: Label1 will show the value for the previously selected record.  In iOS the Set action is being completed before GalleryScreen1.Selected is updated.  This is not the expected behaviour.

The issue is independent of the order of the Navigate and Set actions in the button OnSelect.

Anyone got any thoughts on how to work around this problem until it is fixed?  If it is fixed?

[KroonOfficeSol]

Again, this is behaviour which comes from the way the screen reacts and loads. A screen which is NOT visible won't preform any actions on the global variable change in another screen. 

So what happens is that

• when you leave the screen (let call this the invisible screen) the value in label 1 is that off the global variable on that time. 
• Then you change your global variable, but on this moment your invisible screen stays the same.
• You go back to the invisible screen then the screen will updates the controls on it with the specific datasource.
• Probably in the app on a ios this process takes more time then in the browser, so you see the value for the previous time for a short moment.
• That the other box has the correct value is just luck and it could be that when you go to this screen a hunderd time it won't be the case in a number off them. Probably this box is updated first and the other second. To test try add a third label en connect it also to the gallery and see what happens. Probably this will be processed after the second box because you added this later to the screen. I'm not sure if this is the case, it could also be that the gallery.selected relations works different in initiating during the onvisible process off a screen then a global variable.

Just try to reset the global variable on the OnHidden Property off the screen like

Set(MyGlobalVariable, Blank())

Then go to the screen again from the gallery and see if this helps.

Then again, why use a global variable and not a local variable you pass to the invisible screen in the navigate() formula. Like

Navigate(TheInvisibleScreen, None, {MyLocalVariable:Gallery.Selected.ID})

There is you're workarond.

btw It won't be fixed, because it aint broken.

Success,

Paul