"This formula may not change the data."

I'm kind of confused by what you have posted...

1) You have 'File XSPF' := createTextFile(this, 'Code XSPF', Name + ".xspf") and the following line says that 'File XSPF' is a Formula field. You can't assign a value to a Formula field outside of the Formula field itself.

2) You say you would like to have one thing open the file, but you are creating a file in your example.

I'm not sure whether you want to combine creating and opening into a single operation or if you just want a way to open the file. Having said that, I don't think you can combine operations.

I found the behavior of the Button element to be inconsistent... You can create a text file with code, but you can't put this code in a Button to open the text file...

file(this, "MyFile.txt")

You can put that code in the "Formula" section of a Formula field and it will open the file, but if you put the code in the Formula field's "On click" section it doesn't work. Kind of a head scratcher.

I see the same issue when I create a Formula in my Ninox db. The formula is good and full working, I test in copy and paste the Formula and the copy to another trigger and don't work I only can see the "This formula may not change the data." message

just to understand your case more... What happens when you put a spiff file in an image field and then click on it? Does it opens VLC? In that case you could say like Image:= 'your .xspf file' (i know if there is a pdf in it, it opens that pdf)

Steven

@alejako, The "Formula" section can't modify data, but the "On click" section can.

@Eric Plet, I couldn't get both to work in a single script. Even if I put the create code in the "On click" section of the Formula field and the open code in the "Formula" section, only the "On click" section works. What code are you using to open the file?

@Sean, I see my issue I must first create a trigger and after I will paste the copy code and all  work fine.

@Eric Plet, I still can't combine create and open, but if I click on the Image field it will open the text file I created. You could at least delete the Formula field that you use to open the file. Maybe someone else can get it to work.