Lookup within Gallery not working correctly

[Anonymous]

Hi all,

I've seen the powerapp platform behave so inconsistently when using the Gallery that it makes me wonder what is a safer alternative. My latest and simplest to explain issue is as follows:

Place a gallery based on a datasource (cached view of SQL DB)

Place an Image within the gallery, with the Image property having the value:

LookUp(dimResidentPhoto, PhotoFileID = ThisItem.PhotoFileID).Photo

And voila, it doesn't look up correctly. On very first load it will actually load fine, but as soon as you refresh/filter the lookups are off. I have confirmed and write out the PhotoFileID alongside the image and they are definitely unique, and there is definitely a different photo for each ID. The filters/data is definitely working fine, only the lookup/image is causing problems.

So even though the ID is different, it always grabs/shows the first photo for ALL gallery elements. Obviously this is a bug, but what are my alternatives?

[RandyHayes · Accepted solution]

@Anonymous 

An alternative is to do this in the Items property of the gallery.

Ex:

AddColumns(
    yourDataSource As _source,
    "_photo", LookUp(dimResidentPhoto, PhotoFileID = _source.PhotoFileID).Photo
)

Then set the Image property to ThisItem._photo

This will perform the lookup as part of the table for the Gallery rather than having each line in the gallery then do its lookup - as this occurs after the rendering of the gallery.

I hope this is helpful for you.

[Anonymous]

Thanks Randy, I have noticed that using a cached view (rather than a DB lookup) also solves the problem.