Installed on date not displayed

[Robert Roth]

Steps to reproduce:
1. Open software center
2. Go to the details screen of an installed application and check the statusbar stating the installation status
3. Click back
4. Click forward, or visit any other installed application
What happens:
2. Only "Installed" is displayed, not "Installed on DATE"
4. "Installed on DATE" is displayed
Expected:
The result should be "Installed on DATE" shown in both steps

Note:
The date is not displayed only for the first opened application, for all subsequent installed applications the date is displayed, so this bug can be reproduced only one time per software center session, to reproduce it again, you will have to close and restart software-center.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: software-center 4.1.22
ProcVersionSignature: Ubuntu 3.0.0-11.17-generic-pae 3.0.4
Uname: Linux 3.0.0-11-generic-pae i686
ApportVersion: 1.22.1-0ubuntu2
Architecture: i386
Date: Thu Sep 15 23:10:42 2011
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Alpha i386 (20110727)
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: software-center
UpgradeStatus: Upgraded to oneiric on 2011-09-15 (0 days ago)

[Robert Roth (evfool)]

This seems to be caused by the lazy loading behavior of the package history: when the get_installed_date is first called,the apt history is not initialized yet, thus it will return None (and we don't display that), and adds an idle callback to rescan the history, which will properly initialize it, that is why subsequent calls work as expected.
I'm not sure what we should do here, as it's either performance (lazy loading helps) or consistency (on first load, we won't have the installed date), I guess this needs a decision to be taken, unless someone finds a third alternative.

[Kiwinote (kiwinote)]

iirc we had huge performance issues if we waited for the history to be loaded, which is why we chose not to display the installed date on first view - you could probably add a callback to update the label once the history has loaded, but imho it's not worth the effort as by the time the history has loaded the user has most likely left the page already

[Matthew Paul Thomas (mpt)]

I like the idea of updating the label once the history has loaded. If you really do want to know the date, having to wait a few seconds may not be obvious, but having to click Back then Forward is much less obvious.