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First function in a gallery not consistent

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Posted on by Woody

Scenario: I have a screen that loads a gallery with values from a filtered query. The gallery is hidden by default, and its visible property is set to true when it is populated with results. This is checked by seeing if the value of the key gallery item’s label is equal to the value I’m expecting (lblName.Text = vAccountName).

The first time the screen is shown, everything works fine. For example, the gallery loads with 20 items. I select a row deep in the gallery (say row 18) and move off the screen to something else. If I navigate back to the screen and this time the filtered query has less results than the first time (say returning 1 row instead of 20), the First([]) function does not fire. The results are that lblName.Text would be blank even though the gallery has items.

If I back up and try it again, it works.

The gallery’s default is set to First([])

The OnVisible event of the screen resets the gallery in question

Has anybody else seen this behavior, or is there another way to ensure the first row of a gallery is selected upon population of data?

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Building Power Apps

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v-xida-msft Microsoft Employee on at

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Hi @Woody ,

Could you please share more details about the formula within the Items property of the Gallery?

Do you want the first item within the Gallery to be selected?

If you want the first item within the Gallery to be selected when your Gallery populated with data, I have made a test on my side, please take a try with the following workaround:

Set the OnVisible property of the first screen of my app to following:

Clear(RecordsCollection);
ClearCollect(RecordsCollection, '20190211_case5')

On your side, you should set the OnVisible property of the screen which contains the Gallery control:

Clear(RecordsCollection); ClearCollect(RecordsCollection, 'YourDataSource')

Set the Default property of the Gallery to following:

First(RecordsCollection)

Set the Items property of the Gallery to following:

SortByColumns(
Filter(RecordsCollection, StartsWith(Title, TextSearchBox1.Text)),
"Title", If(SortDescending1, Descending, Ascending)
)

On your side, you should type:

SortByColumns( Filter(RecordsCollection, StartsWith(Title, TextSearchBox1.Text)), /* <-- Use RecordsCollection as data source within your Gallery instead of your original data source*/ "Title", If(SortDescending1, Descending, Ascending) )

Please check the attached GIF screenshot for more details:

Best regards,
iAm_ManCat 18,256 Most Valuable Professional on at

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Hi,

Did you check/test that your reset is not clearing the Default value (rather than 'resetting to default') when reset as it may not be able to check First() during the reset action.

I would try to set a variable on App start
Set(FirstGalleryItem, First(DataSourceThatGalleryUses))

Then for your gallery default have it set to FirstGalleryItem - this won't be affected by any reset function performed on the gallery itself.

I hope this helps towards your solution 🙂
Woody 4 on at

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So, I'm not using a collection because the data set in this case is filtering 35,000 records, and I don't want to have to download the full data set down to someones device. The fields used in the filtering vary depending on the logic of the prior form.

The bigger issue that I'm having is that even though the records are changing in the gallery, when I come back to it, the gallery still is thinking that a record way at the bottom is still selected (even if there is no record at that index anymore)
Woody 4 on at

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I'm probably not explaining my situation very well. The first function works just fine either the first time the screen is run, if the data set has been cached in the past, or the results return more rows than the row that was previously selected.

However, if during the same session with the app, you navigate to the screen with this gallery and the result of the filters return less rows than where you might've clicked in the list the first time, nothing is selected (first or otherwise).

I really think this is a bug.