[Qgis-developer] 1:many relation enhancements

[Matthias Kuhn]

Hi Régis

On 10/21/2014 09:44 PM, HAUBOURG wrote:
> Hi Matthias,
> Agregate functions could be provided by virtual table feature (qep is coming I think), I suppose we should chose one common way for advanced relationnal capabilities.

I agree that one common way is preferable, but actually this QEP itself 
is already duplicating functionality (of QgsExpression) and nobody was 
able yet to confirm that it is possible to optimize queries for 
execution on the database with sqlite virtual tables. Something that is 
a must from my point of view. I think it is a good initiative, but for 
the aforementioned reasons I am not yet completely convinced, that it's 
the one and only way.

>
> About filtering, you're right,  we can't assume children table to be geographic.

... and neither for the parent ...

> I was thinking of a search bar on top of the dialog showing new children candidates. That search bar could have a qgsexpression widget on its right to enable a permanent filter + a field chooser to choose on what field apply the user entries of search bar. why not have parent geometry accessible in expression builder and let the power user make spatial filters?
Yes, once there are expressions available the parent feature should be 
available for evaluation. Now I am not sure if I understood correctly. 
Are you referring to a filter to show only a subset of the related 
children or a filter to search for new children which you want to link 
to the current feature?
I was also thinking of improving the search field to link additional 
features (or change the parent of a feature) but that would mainly make 
sense (in my scenarios) if this could be evaluated server-side and that 
would require a project "expression compiler" for which I am currently 
also looking for funders :-)
> ..
> Thanks for the tip on qtcreator, I worked on 2.4… now I know it's done ;-)
> By now, no direct funding is possible for me (administrative blockers). I wish I could finance your work on unit tests first, but it is currently forbidden to french administrations..
I thought this barrier mainly exists for "funding" as such (like in unit 
tests, but thank you for mentioning it), but not for a particular 
contract work with a requirements document for a new feature? But you 
surely know better.

All the best,
Matthias

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