Server error on admin preview of VirtualSourceObject

https://github.com/lektor/lektor/blob/9ede53d740e76f785babf81cb0cab5c92c9a16c5/lektor/admin/modules/api.py#L134-L141

Should a virtual object be treated differently by the admin UI in regards to the navigation redirect? The highlighted snippet above results in a TypeError: object is not subscriptable on the attributes _path and _alt. Further, if you provide a path, the admin UI will redirect to that path. Which is funny because the error happens while the correct page is being displayed. I believe the correct behaviour is to prevent any further navigation if isinstance(record, VirtualSourceObject)?

[dairiki]

Should a Page not return jsonify(exists=True,... instead of jsonify(exists=False,...?

Indeed. I think you maybe missed the not in front of isinstance. 😉

No need for me, I’ll update once its ready.

Great! I’ll close this issue. Feel free to re-open if there’s trouble.

[relikd]

I’m not sure I understand. Page is a subclass of Record (as is Attachment, Image, etc.) If record is an instance of Page, then isinstance(record, Record) will be true. (A instance of a subclass is also an instance of any superclasses.)

Yes, that is why I ask. Should a Page not return jsonify(exists=True,... instead of jsonify(exists=False,...? I thought a Page should evaluate as it did before? Only virtual objects and assets cause problems, so these two should return False whereas a page should return True? – Or: which records remain if you test for isinstance Record? When does it evaluate to true?

Is it worth back-porting this fix to the 3.3 branch (and making a 3.3.x release)? Or can you work from the master branch for now?

No need for me, I’ll update once its ready.