Files app ajax call exception must be shown in popup

[PVince81]

Steps to reproduce

Hard to reproduce, but met while working on #5199

1. Follow the steps in that ticket
2. At some point you'll have to click on the external storage mount subdir
3. list.php will return an exception in the form of an HTML page

Expected result

Exception / stack trace shown in popup dialog

Actual result

Fails silently and stays in the same directory (and URL points to the wrong subdir)

Ideally the server should return the strack trace inside a JSON object instead of returning a whole HTML page when calling in ajax mode. This can be detected from the XmlHttpRequest headers.

[DeepDiver1975]

there is a try catch block in index.php - any unhandled exception will go in there.
Currently we simply generate an html error page - but we should honor the accept header and return at least json if requested.
Maybe xml would be valid for OCS calls @karlitschek

[karlitschek]

great idea. I'm not sure if this is a topic for OCS because this is only for debugging as far as i understand.

[DeepDiver1975]

this is only for debugging

It will help while debugging but it will also help in regular/productive operations where exceptions are no handled properly in the code.

[PVince81]

Ideally I'd like to return JSON for when the call is made using Ajax.
Is there a way to detect when a call is made to the API ? Does it go through index.php at all or are OCS API calls going through another script ?

[karlitschek]

Can you explain the usecase why we want to expos this via a public REST api? I can't see it at the moment.

[PVince81]

I think what @DeepDiver1975 means is that if you make a REST API call and that one causes an exception on the server, that you'd still get a stack trace (or at least the exception's message) in the response instead of... whatever is returned now ?

I'd say we can consider this as a separate use case / issue.

In this ticket I'd prefer to focus on showing the exceptions caused by ajax calls in the UI.

[karlitschek]

yes please.

[PVince81]

After discussing it with @tanghus we decided to go with just logging the stack trace.
This is done in #5478

[DeepDiver1975]

@PVince81 this can be closed - right?

[PVince81]

Closing