Using Buttons to Filter Lists - List Won't Filter

[abic131]

I have an application with 3 screens, HomeScreen, Screen1 and Screen2. I have two buttons on HomeScreen. The first button takes you to Screen1 which just shows an unfiltered list (Table1). The 2nd button takes you to Screen2 which is 2nd unfiltered list (Table2).

Screen1 and Screen2 are related by an identifier (ID). There are arrows on each of the Screen1 list items, and when I click them I'd like it to take me to Screen2, and filter the Screen2 list by ID.

Here is what I have so far.

On the Home Screen:

Screen 1 Button (to navigate to Screen1) - OnSelect (this works)

Navigate(Screen1,ScreenTransition.None)

Screen 2 Button (to navigate to the unfiltered list on Screen2) - OnSelect (this works)

UpdateContext({vFilter:Blank()});Navigate(Screen2,ScreenTransition.None)

On Screen 1:

Screen 2 Button (to navigate to filtered list on Screen2) - OnSelect (this does not work, brings me to unfiltered list)

UpdateContext({vFilter:ThisItem.ID});Navigate(Screen2,ScreenTransition.None)

On Screen 2:

Gallery Items

If(IsBlank(vFilter),Table2,Filter(Table2,ID=vFilter))

Refresh Button (to unfilter the list) - OnSelect (Can't tell if this works because my list will not filter)

UpdateContext({vFilter:Blank()})

I've tried a few things. I can get the list to filter by vFilter if I forgo the if statement, but that means I can only get to a populated Screen2 through Screen1, and I want to be able to get to it unfiltered through the home screen.

I tried adding- UpdateContext({vFilter:Blank()} to the OnVisible action for Screen2 but that didn't work, which is why I moved it over to my OnSelect for my refresh button.

Any ideas are appreciate- I am very new to this. Thanks!

[BCBuizer · Accepted solution]

Hi @abic131 ,

The UpdateContext function creates a context variable which only works in the context of the screen where it is created. So, when setting a context variable in screen1 and then expect it to work in screen2 is not realistic. 

There is a way to set a context variable in another screen though, using the Navigate function. You can use the below to replace the formula for the button on screen 1 that is not working:

Navigate(Screen2,ScreenTransition.None,{vFilter:ThisItem.ID})

[AaronKnox · Accepted solution]

Hi @abic131 ,

UpdateContext is scoped to the screen so when you navigate to a new screen the value of vFilter is lost.  You are really close to the solution, however:  Navigate() allows for local variables to be added to the screen you are navigating to, so just change the Screen 2 Button.OnSelect formula to

Navigate(Screen2,ScreenTransition.None, {vFilter:ThisItem.ID} )

Hope this helps!

Aaron

[abic131]

Thank you both! That worked.