Power Platform Community Forum Thread Details

Hi community!

I am building a POC for a timeclock system using an NFC tablet and Power Apps. The tablets are permanently mounted at entry and exit points in several locations. Staff use an NFC device, either a card or a digital wallet on their phone, to clock on and off by tapping their device against the tablet.

My app has a button called btnScanCard with the following code on the OnSelect property:

With(
 {nfcInput: ReadNFC()},
 IfError(
 nfcInput,
 If(
 FirstError.Message = "Tag not found",
 // No tag detected
 If(
 ckbAutoScan.Checked,
 // TODO: re-run the OnSelect of this control
 true
 ),
 // Error with detected tag
 Error(
 {
 Kind: ErrorKind.NotFound,
 Message: "We couldn't read your tag. Please try again."
 }
 )
 )
 );
 /*
 Lookup user and do stuff
 */
 If(
 !IsBlank(nfcInput),
 Navigate('Welcome User')
 )
)

I am running into issues with the ReadNFC() function not staying active for more than a minute or so. At which point, the button must be selected again. I need the NFC reader to be active until a device is scanned.

I've been trying to circumvent the self-referential rule by selecting controls which select this control, but Power Apps seems to be aware of all the indirect references. I've also tried using a checkbox, e.g., uncheck and check it and have the Select statement run on check; however, that approach didn't work.

I was able to navigate away from the screen and back to it and then run the Select() but that seems overkill. It's a simple while loop. Should I use a timer for this?

Would love to hear some approaches to this.

Thanks