[QGIS-Developer] Virtual Layer & Unique identifier column?

[Richard Duivenvoorde]

Ok, I created a PR to 'fix' some of the ui quirks:

https://github.com/qgis/QGIS/pull/44879

Anybody can answer the question how to distinguish in the code between being called from a layers context menu vs being called via the QGIS menu (for a new layer). If that is possible I could change the text on the buttons and disable some parts.

And... I'm wondering: should we 'streamline' this dialog more with the 'query layer dialog'?

And "what is the unique identifier for" I still wonder?

Regards,

Richard Duivenvoorde

On 8/25/21 4:01 PM, Richard Duivenvoorde wrote:
> We (Raymond and me) have some issues with Virtual Layer functionality.
> 
> Who knows what the actual use is of the 'Unique identifier column' of the dialog? Because without it it also works...
> 
> Main point: if you click/use the 'Unique identifier column', and use a NON unique column(!), you are practically filtering your data.... but it's not clear WHAT is used or filtered ... and as an example: the feature count then still shows 5 but the attribute table only shows 3 (filtered)
> 
> What do other providers do in such case (I think postgis tells you: "hey that column is NOT unique"?).
> 
> We found other ui-related things, which we were not sure if it is interesting enough to create issues for:
> - clicking Help button does NOT bring you to: https://docs.qgis.org/testing/en/docs/user_manual/managing_data_source/create_layers.html#creating-virtual-layers
> - you can click the 'Unique' checkbox without giving the actual column (could be checked for?)
> - test button does not check for missing unique column name
> - removing the checkbox (and overwriting the layer) does not remove it (unless you also remove the column name)
> - if you 'edit' a v-layer (via context menu) you are still being asked to overwrite/create the layer
> - creating a new geometry without a crs seems possible (could be checked for?)
> etc
> 
> Would this be a good candidate for some nice re-work? We do have some idea's and (other) issues :-)
> Our feeling is that current status could need some QGIS-love...
> 
> Regards,
> 
> Richard Duivenvoorde
> 
> 
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