Gallery not rendering correctly on first load

[rdorman]

I have a booking system app with multiple screens. Three of these screens display different views of the booking data.  The booking data is stored in a SharePoint list.

The first view screen displays fine.

On the second view screen, the gallery is meant to display all bookings for the next month. When this screen loads initially, the data flashes for a microsecond and then the text seems to disappear and the gallery looks like a series of blank rows, one for each record that is meant to appear (there is a View button in each row, and this still renders), and clicking on the row performs the OnSelect event for the row (opens the record in read mode).

If there are no bookings the gallery is hidden and a no bookings available message is shown, so I know that it's not that there are no bookings. If you navigate to another screen, and then return, the view renders correctly :

The visible property on the labels that display the record content are always set to true.

In the OnVisible event of the screen I have 

Reset(compHeaderScrNext30Days);
Reset(cmbPickUpDateFilter);
Clear(colFilters);

With(
{
    monthFromNow: DateAdd(Today(), 31, Days)
},
UpdateContext({locHasRecords: !IsBlank(LookUp('Booking Requests',  (Start >= Today() And Start < monthFromNow) And Or(Status = "Booked", Status="Taken")))});
ClearCollect(colNext30DaysBookings, Sort(Filter('Booking Requests', Start >= Today(), Start < monthFromNow, Or(Status = "Booked", Status = "Taken")), Start, Ascending));
);

UpdateContext({locDateFilterOptions: ForAll(Distinct(colNext30DaysBookings, 'Pickup Date'),
{
    displayDate: Text(DateValue(Result,"uk"), "mmmm dd, yyyy"),
    valueDate: Result
})});

The variable locHasRecords is a lookup I perform to see whether there are going to be any records to render. This is what is meant to control whether or not the gallery is displayed.

colNext30DaysBookings is the collection used by the gallery in it's Items property.

locDateFilterOptions is the list of dates used in the filter field.

If I hard code locHasRecords to be true, then the gallery renders everytime without issue. If I use the above lookup, I get the render issue, but the gallery itself is not hidden so it can't be false. When I look at the value of the variable, it is definitely set to true by the lookup.

Does anyone have any ideas what I can try?

For reference, the gallery Items property is set to:

If(!IsEmpty(cmbPickUpDateFilter.SelectedItems), Filter(colNext30DaysBookings, ThisRecord.'Pickup Date' in cmbPickUpDateFilter.SelectedItems.valueDate), colNext30DaysBookings)

and the visible property is simply 

locHasRecords

The third view screen of my app is also suffering this issue, but is much simpler as it does not have a filter field.

[v-jefferni]

Hi @rdorman ,

Please try below steps:

1. Add a Label in your App and set Text to the variable locHasRecords, see if it updates correctly when navigating to this screen.

2. change the formula of this variable:

UpdateContext({locHasRecords: !IsBlank(LookUp('Booking Requests', ((Start >= Today() && Start < monthFromNow) && (Status = "Booked"||Status="Taken"))))});

 3. Change the formula of With function completely:

Set(
    monthFromNow,DateAdd(Today(), 31, Days)
);
If(!IsBlank(LookUp('Booking Requests', (Start >= Today() && Start < monthFromNow) && (Status = "Booked"||Status="Taken")))),UpdateContext({locHasRecords: true}),UpdateContext({locHasRecords: false}));
ClearCollect(colNext30DaysBookings, Sort(Filter('Booking Requests', Start >= Today(), Start < monthFromNow, Or(Status = "Booked", Status = "Taken")), Start, Ascending));

Best regards,

[rdorman]

Thanks for trying to help @v-jefferni.

I already had a label on my screen and it is always showing true as the value for locHasRecords.

I changed my formula to the below based upon your suggestion, but it's still doing the same thing:

Set( monthFromNow,DateAdd(Today(), 31, Days) ); 
UpdateContext({locHasRecords: !IsBlank(LookUp('Booking Requests',  (Start >= Today() && Start < monthFromNow) && (Status = "Booked" || Status="Taken")))});
ClearCollect(colNext30DaysBookings, Sort(Filter('Booking Requests', Start >= Today(), Start < monthFromNow, Or(Status = "Booked", Status = "Taken")), Start, Ascending));

The funny thing is that the values do appear for a microsecond, but then they just disappear. It's like something is making the labels disappear or setting their text to blank, but this should not be possible as their Visible property is set to true, and their text property is set to ThisItem.RelevantPropertyName

[v-jefferni]

Hi @rdorman ,

Please try: Add another Gallery, Visible set to the variable as well. Gallery Items move the If statement into Filter function and use it for the criteria:

Filter(colNext30DaysBookings, If(!IsEmpty(cmbPickUpDateFilter.SelectedItems),'Pickup Date' in cmbPickUpDateFilter.Selected.Date),true))

The reason is that I used to encounter an issue, which is complex tables/data sources as one of the parameters in an If statement always return blank result. Moving If statement into a single Filter is much simpler and could avoid this issue.

Best regards

[rdorman · Accepted solution]

So I have managed to discover the cause of the issue. It would appear that one of the label controls displaying the data in the gallery had AutoHeight set to on. On initial load, it was making this label so large that it would cover the entirety of the data display area, forcing the actual content to be out of site.  I only discovered this as I have a tooltip defined for the label and hovering in the gallery was always displaying that tooltip regardless of where you hovered.

Thanks anyway.