[Qgis-developer] Questions/Suggestion on virtual layers

Neumann, Andreas a.neumann at carto.net
Wed Mar 2 07:27:07 PST 2016


I am experimenting with the virtual layers. They are quite cool! 

I have some suggesions/questions: 

 	* It would be nice to have a preview of my query results. Currently it
is either it works - or not. If it works, but the results are wrong you
have to start from scratch. I would suggest that when you press on the
test button you would not only display "No error" or the error message,
but maybe the first 10 rows of the result.
 	* Updating the virtual layer: it would be really nice if I could
edit/improve on my virtual layers without having to start completely
from scratch. --> Oh - now I found out that if you select an existing
virtual layer and then use "Layer" --> "Add Layer" --> "Add Virtual
Layer", that you can refresh an existing virtual layer. This is really
not obvious. I think this is more a usability issue.
 	* it is not very obvious how you can reuse an already existing
geometry column. I discovered it by accident, that you can use
layer.geometry (regardless of the original name of the geometry column),
but I think that it is not obvious. A better hint in the the tooltip
would probably help.
 	* Unique identifier column: If you join several tables, you often have
the issue that you need to create an artificial primary key. Could we
offer a preconfigured builtin pkey - something like a rowid  for such
 	* What is the exact purpose of the "Embedded Layers" where you can
add/import/remove layers? I noticed that existing layers of the project
work anyway without adding/importing them first. Is the idea that you
can work on layers that aren't in the project?

Should I open feature request tickets for these or are there already
plans to address one or the other of the above issues? 

Thanks anyway for this interesting new feature! 


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