[Qgis-developer] Change the query of a query layer (postgis)

[Olivier Dalang]

Hi !

Is it possible to change the query of a postgis query layer in python
without reloading the project ?

The goal is to have a parameter in my query that I'd be able to change with
a slider.

I tried the QgsVectorLayer.setDataSource() method, but it makes QGis crash.
I tried the workaround described here (
http://gis.stackexchange.com/questions/62610/changing-data-source-of-layer-in-qgis
), writing and reading the XML file, but it also makes QGis crash.

If not possible, is there a serious limitation behind this, or is the
feature just missing/bugged ?

Example :

I have this query loaded as a layer:

"SELECT id, name, ST_Buffer(geom,25) as geom FROM my_table"

But I want to be able to change the hardcoded buffer from 25 to some value
from a QSlider.

Thanks!

Olivier
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