Can't view item when client timezone is greater than loan window

[dlasusa]

Running version: 0.4.1

We've had a strange issue come up where an end user located in Hong Kong tried to get a loan. Loan duration for the item is 3hrs.

The "Get Loan" button works and the additional popup about taking the loan also works, but when the Universal Viewer attempts to load the content it continually refreshes.

In the server logs we see (repeated over and over):
log(f'returning manifest for {barcode} for {anon(person.uname)}')

In the browser it keeps making a call to:
'/manifests/<barcode:int>'

When we have the end user change their timezone to Pacific (where we are located) the viewer is able to display the content as expected. Additionally, if we change the timezone on a test client locally to Hong Kong (we also tried Germany - so any timezone beyond the 3hr loan window) that also failed.

Changing the timezone on the server to GMT didn't seem to help.

Though we noticed with the server set to GMT, we were able to take loans out if the client was in the Pacific timezone. So as long as the client time is BEFORE the server time + loan duration, things work as expected.

We're unsure where the communication between the server and the browser is breaking down regarding the timezone/loan duration.

Any idea what might be causing this?

Thank you,
Dan

[mhucka]

I'm not 100% sure, but we may have had a user in Norway experience the same problem. (I say think beause it didn't occur to us to try to have them change the time zone, but the repeating-reload behavior sounds the same.) We think it was solved in version 0.5.x. Is it possible for you to update to that version? We do understand that the changes in 0.4→0.5 may require some work to update, but it might solve this particular problem.

[dlasusa]

Thanks! We'll try and do that. We've made a variety of changes to the 0.4.x code, so it might take some time. Have most of the changes for 0.5.x been in server.py?

[mhucka]

Have most of the changes for 0.5.x been in server.py?

Unfortunately, no :-(. The changes touched almost everything, including the templates and settings.ini file.

Do your changes concern things that would be worth incorporating back into DIBS, or are they more about site customization? If they're general changes, I wouldn't mind finding out what they are, and trying to see if they could be incorporated into DIBS. That might be useful to other people and might reduce what you have to do to move to 0.5.

Otherwise, in terms of transitioning to 0.5, what comes to mind is the following approach: doing a diff of your current codebase against the unmodified 0.4 codebase to get a full list of your changes, then taking that list of changes and systematically walking down the list while looking at the 0.5 codebase, and (manually) working out how to replicate the changes in 0.5. That may sound painful, but my gut feeling is that it may not take that long to do, especially if done iteratively (do a pass to handle the really easy cases, cutting down the list, then do another pass for harder cases, again cutting down the list, and so on). I could try to help figure out the hardest ones where 0.5 changed so much it's not obvious how to recreate the change.

[mhucka]

Just thinking further: if it would help, I could generate a diff of the 0.4 → 0.5 differences and try to write some kind of roadmap or guide.

[mhucka]

I just reread your original bug report and just realized you described a way to repeat the error. I will check this in 0.5 tomorrow.

[dlasusa]

Looks like we may have found a fix.

We changed the uv.tpl from this:

// Calculate the delay to exiration (in msec) and force a reload then.
var now = new Date().getTime();

To:

// Calculate the delay to exiration (in msec) and force a reload then.
var now = new Date().toLocaleString('en-US', {timeZone: 'US/Pacific'}).getTime();

This seems to work for all of our test clients.

The only downside (though it doesn't seem to affect functionality) is that the "Loan End Time" in the viewer shows in Pacific time instead of the user's local time.

Hope that's helpful! Thank for your quick replies!

[mhucka]

@dlasusa Very sorry about how long this took to get back to. I'm making this change in the code and will release a new version.

[mhucka]

This is in commit 6e806b9.