[Engine-devel] Sorting in tabs

[Einav Cohen]

> ----- Original Message -----
> From: "Lior Vernia" <lvernia at redhat.com>
> Sent: Thursday, June 27, 2013 8:53:59 AM
> 
> 
> 
> On 27/06/13 15:37, Einav Cohen wrote:
> >> ----- Original Message -----
> >> From: "Eli Mesika" <emesika at redhat.com>
> >> Sent: Thursday, June 27, 2013 6:46:58 AM
> >>
> >>
> >> ----- Original Message -----
> >>> From: "Lior Vernia" <lvernia at redhat.com>
> >>> To: engine-devel at ovirt.org
> >>> Sent: Thursday, June 27, 2013 10:12:33 AM
> >>> Subject: [Engine-devel] Sorting in tabs
> >>>
> >>> Hello everyone (UI peeps in particular),
> >>>
> >>> I've pushed (not yet merged) a patch that would enable us to keep items
> >>> in tabs (main/sub) sorted at all times by setting a comparator in
> >>> SearchableListModel:
> >>
> >> But tabs includes only 100 records and supports paging , how you deal with
> >> that ???
> > 
> > if this is in the GUI level, then I assume that the comparator is simply
> > comparing the
> > items within the current page, and not "globally".
> > so the sorting doesn't affect the set of items that is displayed in the
> > page (it would
> > be the same as before the sorting) - just their order.
> 
> Yes, if I understand correctly how the paging works, Einav is correct -
> only the items passed to the UI are sorted.
> 
> > also: @Lior - what happens when the search query contains a "sort by" part?
> > there is a chance that the behaivor would be unexpected in this case;
> 
> Yes, I thought about this case, and it may result in a confusing user
> experience if developers aren't careful. Together with the issue of
> paging, this probably makes this sorting mechanism a better candidate
> for use within subtabs rather than main tabs.

note that at some point, I think that we would want to introduce paging also to search-
based sub-tabs - it will be useful especially for sub-tabs that potentially display a 
large number of results (e.g. Disks sub-tab in Storage main tab). 
In addition, at some point, we would want to get rid of the paging UI as it is now 
(i.e. "next"/"prev" buttons at the top panel) and move to paging triggered by scroll 
(i.e. have a very long grid, dynamically loaded as you continue to scroll - similar 
to the behavior of some e-mail web-clients, for example). In this case, sorting on 
the client side will make no sense at all (i.e. from the user perspective, only a 
portion of a very large grid will be sorted, the other portions won't be).

So for now - yes, I think it makes sense to introduce your mechanism to all sub-tabs, 
however in the long-term - we would probably want the search-based sub-tabs (which 
will support paging) to move to search-based sorting, rather than GUI-based-sorting.

BTW (maybe the other GUI maintainers can help me with that one) - what about sub-tabs 
that are not search-based (i.e. display results from a "regular" query or even from a 
field within the selected item in the main grid, e.g. Applications in VM) - are these 
managed via SearchableListModel as well? since the comparator mechanism *is* relevant 
for them.

Also: Worth mentioning "Bug 893999 - webadmin: please allow column sorting", which 
requests to enable sorting when clicking on a grid-column header; when implementing 
column-sorting, probably worth attaching your mechanism to it somehow (i.e. clicking on 
a column header should set the relevant comparator in the relevant SearchableListModel).

> 
> > 
> > I believe that the correct thing to do is to "attach" the GUI sorting
> > mechanism
> > to the one in the search mechanism.
> > 
> > thoughts?
> 
> This can be done, however I'm not sure there's much utility in it. Main
> tabs are always sorted according to some default ordering even if one
> was not entered in the search panel, and this sorting is also performed
> consistently with respect to paging. So maybe the right thing to do
> would be to just "block" the GUI sorting mechanism for main tabs (i.e.
> override the setter method and make it no-op)?

yes, and related to what I mentioned above - at some point in the future, we'd might want 
to block it for search-based sub-tabs as well.

> 
> >>
> >>
> >>>
> >>> http://gerrit.ovirt.org/#/c/15846/
> >>>
> >>> If a comparator isn't set, then everything should behave as before. If a
> >>> comparator is set, then from that moment on the tab items will be kept
> >>> in a SortedSet, so that even if an item is added in a way that doesn't
> >>> trigger an event (e.g. getItems().add()) the items will be kept sorted
> >>> according to the given comparator. If the comparator is set to null,
> >>> from that moment on the tab should revert to its old behaviour.
> >>>
> >>> You're most welcome to have a look and let me know if this might break
> >>> something (remember though that it's not obligatory to set a comparator,
> >>> so only possible breakage should be in generic flows).
> >>>
> >>> Feel free to use it once it's merged; along with SortedListModel, this
> >>> should make sorting less painful. Just keep in mind that once you set a
> >>> comparator, you can't cast getItems() to a List. This shouldn't be a
> >>> problem in general, as mostly it's as useful (and probably more correct)
> >>> to cast to a Collection.
> >>>
> >>> Lior.
> >>> _______________________________________________
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> >>> Engine-devel at ovirt.org
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> >>>
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