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List:       qgis-developer
Subject:    Re: [QGIS-Developer] Inserting provider filter just before PostGIS layer is loaded?
From:       Johannes_Kröger_(WhereGroup)_via_QGIS-Developer <qgis-devel
Date:       2022-08-30 16:10:14
Message-ID: 71a1cd53-8c7f-410c-51de-ab3e1a1d8dc0 () wheregroup ! com
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Thomas B sent me a suggestion off list and allowed me to share it:

QgsProject.layersAdded.connect(func) actually seems to emit in just the 
right moment. This feels super finicky but so far it has worked 
flawlessly to set the layer.setSubsetString() *before* the actual query 
goes out to the DB. Hope I don't jinx it by posting ;)

Handle with care, and thanks Thomas!

Cheers, Hannes


Am 09.08.22 um 11:15 schrieb Johannes Kröger (WhereGroup) via 
QGIS-Developer:
> Howdy!
>
> I'd like to force a provider filter when a user adds a PostGIS layer 
> and have it applied *before* any data is loaded. Setting it after the 
> layer (and some of its big data) is loaded initially is not an option.
>
> Is there a way to sneak in between "user clicked something in the GUI 
> to load a table/query and QGIS will construct a QgsVectorLayer now" 
> and "QGIS now talks to the PostGIS database to get the data for the 
> new layer", maybe with a signal?
>
> Something like a "layerAboutToBeLoaded" (like the opposite 
> layerWillBeRemoved on 
> https://qgis.org/pyqgis/master/core/QgsProject.html) basically. :o)
>
> Cheers, Hannes


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