Variable resets when navigating to another screen

[joef]

Happy Friday All,

I am having an issue with one of my variables..

I have a button that will remove items from a SPO list, and then navigates to a gallery of items for my users to select.  If they hit that button, they want to edit their items.  The gallery items are set to edit when the Var = true.

I want the variable to be set to true so they don't have to click edit when they enter the gallery. (Too many clicks BAD!!)

On the button I added the below code.

After this fires off and navigates to the other gallery, variable it is not set. (no value ??!!) 

If I remove the navigate it sets it fine. 

The only time I set it to false is after a save and "On Start" of app. 

Does the navigate clear variables?? (that would be bad)

I don't reset the gallery 

RemoveIf(EmployeeTime,
EmployeeEmailAddress = VarUserID &&
Period = Var_CurrPeriod);

Navigate(Gallery3,ScreenTransition.None) ;
UpdateContext({Var_GalleryEdit:true});

TIA,

Joe

[notj · Accepted solution]

You need to use Set instead of UpdateContext.

Context variables are scoped to a single screen. Set is for global variables.

More about variables: Understand variables in canvas apps - Power Apps | Microsoft Docs

UpdateContext: UpdateContext function - Power Apps | Microsoft Docs

Set: Set function - Power Apps | Microsoft Docs

[RandyHayes]

@joef 

UpdateContext sets screen scoped variables only.  If you need your variable to be available across screens, you need to use Set to do so.

However, with navigate, you can set the screen variable of the screen you are navigating to in the Navigate function:

   Navigate(Gallery3,ScreenTransition.None, {Var_GalleryEdit:true})

I hope this is helpful for you.

[joef]

Thanks @notj ,

I had to remove all updateContext in all my screens for this variable to work..

My understaing of global variables was that you set them "On Start", then updateContext after that.

I changed all my variable to Set() not UpdateContext()

Thanks for you help!

Joe

[joef]

Thanks again @RandyHayes ,

I like updating in the navigate!!

[RandyHayes]

@joef 

Yes, I recommend (and as recommended also by Microsoft as well), keep your variables to a very limited minimum. 

Also keep any variables that do not need global scope (Set) set to a screen (UpdateContext).  Also, make extended use of the With function to reduce variables even further.

Also - keep in mind Controls are Global.  If you need the text property (for example) from a label on one screen to be used on another, you do not need to set a variable for it, you can just refer to that text property anywhere in your app - label1.Text

[joef]

@RandyHayes ,

Yes I try to keep them to a minimum, but I use them to prevent delegation issues...

ALL my list are more than 500 items 🙂

[RandyHayes]

@joef 

This is where With will be your best friend!  You can "with" the scoped variable that you want and then use that in the formula to avoid delegation.

ex.

Filter(anotherList, columnValue = oneValue + another + LookUp(someList, ID=1, somecolumn))

Will for sure give you delegation issues.

This formula:

With({someValue: oneValue + another + LookUp(someList, ID=1, somecolumn)},
    Filter(anotherList, columnValue = someValue)
)

Will not, and the variable someValue will only be used in that formula.  It does not "junk" up your app with a bunch of variables that are only used in one place.

[joef]

That's interesting... I have been asking and looking for a solution for delegation since I started with PA.  You are the first person to mention "With".

Have a great weekend!!

[RandyHayes]

@joef 

Like I say...once you start using With - it will be your best friend (along with Coalesce, and a few others).

Have a great weekend also.