Button DisplayMode failing with multiple users

[DGWolfe]

Hi all,

I have a somewhat simple registration app. Users can scroll through a gallery of courses and register to attend.

On the DisplayMode property I have a formula (see below) that counts the course "Capacity" column (in SharePoint) and then determines if there are spaces left, the button remains in edit mode, but if the course is full, it disables.

This works well 98% of the time. But twice now, when we have added new courses, there is an influx of user registration, and the formula is failing, allowing for people to continue to register, even though the course is full.

I have noticed, once the count goes into -minus, the formula fails, and thinks the capacity is still okay to register.

I have used two formula's both work, but have they same glitch if the registrations go into minus.

DisplayMode property of the button:

Option 1:
If(
    ThisItem.'Total capacity' = Sum(
       ForAll(
            Filter(
                SP List,
                'Walk ID' = ThisItem.ID
            ),
            1
        ),
        Value
    ),
    DisplayMode.Disabled,
    DisplayMode.Edit
)

Option 2:
With(
    {
        _Walk: Filter(
           SP List,
            'Walk ID' = ThisItem.ID
        )
    },
    If(
        ThisItem.'Total capacity' = CountRows(_Walk),
        DisplayMode.Disabled,
        DisplayMode.Edit
    )
)

Is there a way to update either formula to failsafe against the count going into minus? I believe that should fix this glitch?

Thanks,

DW

[WarrenBelz]

Hi @DGWolfe ,

The second one is probably better

With(
   {
      _Walk: 
      Filter(
         SP List,
         'Walk ID' = ThisItem.ID
      )
   },
   If(
      ThisItem.'Total capacity' = CountRows(_Walk),
      DisplayMode.Disabled,
      DisplayMode.Edit
   )
)

but how can the count be negative ?

[DGWolfe]

@WarrenBelz, apologies, yes, you are correct. No negative. I have a label in the gallery that counts the remaining spaces left for each course. However, the few courses that have glitched, show negative spots, but it is just a count formula.

I have taken a second look at the button's on select. It's a collection and patch (due to the fact I am pulling data from both a SharePoint list, and a few other inputs and patch all to a second SharePoint list.

I just cant figure out why I have two courses now, where the button has failed to disable because the capacity is full?

[WarrenBelz]

@DGWolfe ,

Maybe some old fashined debugging on two labels in the gallery

With(
   {
      _Walk: 
      Filter(
         SP List,
         'Walk ID' = ThisItem.ID
      )
   },
   CountRows(_Walk)
)

and 

ThisItem.'Total capacity'

[DGWolfe]

@WarrenBelz thanks.

I have manually corrected the entries from the back end. But I added the above, and they are returning the correct counts. It's just stumped me why two have failed but the rest have all worked as expected.

DW

[WarrenBelz]

Hi @DGWolfe ,

It would puzzle me as well if the two labels in the gallery show equal values and the button was still enabled.

[DGWolfe · Accepted solution]

@WarrenBelz I think I fixed it.

https://learn.microsoft.com/en-us/power-platform/power-fx/reference/function-table-counts says that:

• If the CountRows(<Data Source>) function is used without filtering, the count might not be 100% accurate, because the cached count updates periodically. If you need precise count and expect the result to be under the aggregate limit, you can bypass the cached count via CountIf(<Data Source>, True).

As such, I've updated the formula to: 

With(
    {
        _Walk: Filter(
            'SP List',
            'Walk ID' = ThisItem.ID
        )
    },
    If(
        ThisItem.'Total capacity' = CountIf(_Walk,true),
        DisplayMode.Disabled,
        DisplayMode.Edit
    )
)

So now I will monitor and see!

Thanks for the help to date!

DW

[WarrenBelz]

@DGWolfe ,

I have used CountRows for many years and have never seen it produce an inaccurate result, but I guess there is a first time for everything.