Choose from list of images to use as thumbnail from Enum List

I have a number of photos that all reference the same item in another table.
I would like to select one of those photos to assign as the items thumbnail image.

I was able to do this in the Items form as a Enum column of a base type of Thumbnail
I then put in this expression in the “Valid if” formula

SELECT(Photos[Image], [Collection_ID]=[_THISROW].[ID], TRUE)

It works great but if I go back into the Items form to edit, the Enum for the Thumbnail shows me a “This Entry Is Invalid” error.

It is still working but I’d like to know if maybe there was a better way for me to accomplish this or fiix this valid error.

Thanks all

Do you have a “Related…” ref_rows() column in the items table that shows a list of photos that reference that item?

Maybe try to simplify the expression to:


Also try to move the expression from valid_if to Suggested Values.


@Marc_Dillon Thanks so much!
Yes I did have “Related…” ref_rows() column, didn’t know it was that easy to get those values like that.

I removed my old the formula from the “Valid If” field.
Then used the following formula in the “Suggested Values” field

[Related Photos][Image]

I did have to change my column type from Enum to Thumbnail.
But now it works great

Thanks again


Do you still get a dropdown selection that way?
Did you try to change the “Base Type” of the Enum column to Thumbnail?

Setting a Suggested Value expression does give a dropdown on a non-Enum field.
I didn’t know…

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Yeah, I was happily surprised too

Yeah, I still got a dropdown selection even though my Base Type was no longer Enum by Thumbnail.

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