[QGIS-Developer] Inserting provider filter just before PostGIS layer is loaded?

[Johannes Kröger (WhereGroup)]

Thank you for the idea! The goal is to sneakily jump in when the user is 
adding any layer though (without them caring about anything, without any 
rules they have to follow). I'll post our solution in the main thread in 
a moment.

Cheers, Hannes

Am 22.08.22 um 12:11 schrieb Jacky Volpes:
> Hi,
>
> I don't know any way to do this, except for using a workaround.
> But it will depend on your use-case.
> Maybe using query layers, such as
>
> QgsVectorLayer("table='(select * from <schema>.<table> <your 
> conditions>)' service='<service>' key='<unique id column>'", "<table 
> name>", "postgres")
>
> can help ?
>
> Regards,
> Jacky
>
>
>
> Le 09/08/2022 à 11:15, Johannes Kröger (WhereGroup) via QGIS-Developer 
> a écrit :
>> 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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>
> -- 
> Jacky Volpes
>
> Ingénieur SIG - Oslandia

-- 
Johannes Kröger / GIS-Entwickler/-Berater

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