Default Selected Item not updating on collection changes

[natvar]

I'm working on an app where you can scan hardware barcode to add it automatically to a multiple values lookup input.

I currently use another screen where I have the scanner and a gallery showing my collection.

My collection has two columns : Id and Value. Such as any lookup item. The scanner add a new item to the collection if the barcode in found in a list. The collection is properly edited. You can also delete items from the gallery.

Now in the form, the data card with the lookup has as default and update the collection. When I scan and add a new item to the collection the lookup input doesn't show the newly added item. Yet when I submit the form, the lookup is correctly assign and in my SharePoint list the item is there.

Even more interesting,  if I go in the formula bar of the default value of my data card, change the collection name then put it back, the field update and show the item.

To me it seems like the field is not properly updating when its default property is changed. It might be a bug as much as an oversight from something in my code.

[jlindstrom]

So here is what the issue likely is:

The field doesn’t actually change until you hit enter or move off the field. This is by design. When you type in the field you hit enter.

so the good news is almost every hardware scanner out there is a setting to make it hit enter after scanning

for example, if you have a Zebra brand scanner, they have a barcode you can scan that will make it enter a carriage return after scanning https://www.zebra.com/us/en/support-downloads/knowledge-articles/evm/how-do-i-enable-a-carriage-retu...

this should fix your problem, as @PowerAddict and I learned a couple of months ago

@natvar if this answers your question please mark it a solution so others can find it 

[KrishnaV]

Hi @natvar ,

Ensure that the collection files are referred properly in the formula.

I hope this resolved your issue if you see any challenge/need further help please let me know I am always happy to do it for my community.

Regards,
Krishna
If this post helps you give a 👍 and if it solved your issue consider Accept it as the solution to help the other members find it more.

[natvar]

Thanks for your answer, but I feel like I didn't give enough precision. So I don't really understand what you are advising me.

I'm going to explain the problem by showing my formulas : 

I'm using the scanner provided by Power Apps, here is what I do on a scan : 

Sanner.OnScan = With(
    {
        found: Filter(
            'Accessories / Hardware',
            Title = Scanner.Value
        )
    },
    If(
        CountRows(found) = 0,
        Notify(
            "The hardware was not found",
            NotificationType.Error
        )
    );
    Collect(
        DeliveredH,
        {
            Id: First(found).ID,
            Value: First(found).'Complete Info'
        }
    )
);

I search for the hardware in a SharePoint list and add it to a dynamic collection (DeliveredH) as a lookup field item. On the same screen I have a gallery showing the items in my collection. If I scan a correct barcode, thehardware appear in the gallery correctly. The issue is not here.

Clicking on the check button navigate back to the form.

As you can see the item does not appear in the field. Yet the code is :

DataCard.Defaul = DeliveredH
DataCard.Update = DeliveredH

And most interesting : if I update the formula of default :

The input update and show my item. Note that the issue is purely visual. If I submit the form, the item will appear in the SharePoint list.

[natvar · Accepted solution]

I found a workaround by myself after some inner self reflection.

From what I can understand : 

The input is not updating since the data that it use is actually Input.SelectedItems. I'm updating Input.Default which is only used during the initialization of the field (which make sense). So in order to show the updated collection, I need to reset the field. But of course you can reset a field only in his own form.

So here is how you do it :

- Add a button to the data card and make it invisible.

- Set his code as follow : Button.OnSelect = Reset(DataCardValue)

Then if you scanner is on the same screen call it in the Scanner.OnScan formula or if you have the scanner in a different screen, call it on the Screen.OnVisible formula : Screen.OnVisible = Select(Button). 

Now the input update each time the screen is visible to the value of the collection. Which is exactly what I wanted. With that you can edit the items in the lookup either via the scanner and it's gallery or directly via the input. Both of them will work and you will have the items in the SharePoint list.

You only need this part of code that I didn't show before as it was not relevant : 

DataCardValue.OnChange = ClearCollect(DeliveredH, DataCardValue.SelectedItems);

I hope that this help people and of course if someone has an improvement I am open to any suggestions.