Fix CoverController::getImageParams isbn array check

[LuomaJuha]

I think this was forgotten in #2633 but the parameters do not work properly when trying to fetch an image to show.

[demiankatz]

Thanks, @LuomaJuha! I'm copying @xmorave2 into this thread in case he has any insights. I thought I had done end-to-end testing of this, but maybe I did something incorrectly or overlooked a detail. It certainly seems like you've found a gap in the code. I also have a couple of questions about implementation details (see below).

[demiankatz]

Why is this reset necessary?

[xmorave2]

Why do you reduce the ISBNs to first one only? We probably want to pass all available ISBNs to cover loader.
So we want something like this instead:

$isbns = $params()->fromQuery($identification);
if (empty($isbns)) {
    continue;
}
if (!is_array($isbns)) {
    $isbns = [$isbns];
}

[LuomaJuha]

Now it should convert them into an array as default. And keep all the array values.

[demiankatz]

I think the VuFind\Cover\Loader is now expecting an 'isbns' key instead of singular 'isbn' in order to take advantage of multiple values. I wonder if 'isbns' => (array)$isbn would be the best way to approach this.

[xmorave2]

Yes we need isbns param instead of isbn.

[LuomaJuha]

isbns it is now.

[xmorave2]

Thanks @LuomaJuha for catching this! It's definitely a bug and my oversight from #2633.

[xmorave2]

Why do you reduce the ISBNs to first one only? We probably want to pass all available ISBNs to cover loader.
So we want something like this instead:

$isbns = $params()->fromQuery($identification);
if (empty($isbns)) {
    continue;
}
if (!is_array($isbns)) {
    $isbns = [$isbns];
}

[xmorave2]

Yes we need isbns param instead of isbn.

[xmorave2]

Thanks for quick update @LuomaJuha. I do some hand on testing using ObalkyKnih driver with ajax covers disabled and it is working fine.

[demiankatz]

Looks good! Thanks, @LuomaJuha and @xmorave2!