Hi Olivier, datasource changing is a feature that I really miss and wait from longtime. Every Qgis new release I checked without success if the properties datasource string is editable. I recently found the hack you report ( https://geogear.wordpress.som/2015/05/15/changing-qgis-layer-datasource-with-python/) that I verify to be working up to Wien 2.8.2. Till 2.9 the code crash qgis. Reading your post I realized that a new QgsVectorLayer method has appeared: setDatasource. Wow! Perhaps the waiting is going to be over....
Regards, Enrico Ferreguti. 2015-06-17 16:45 GMT+02:00 Olivier Dalang <olivier.dal...@gmail.com>: > Hi Enrico, > > Hmm I didn't think of that, thanks for the idea ! But I can't use it since > I may have several user at once. > > Best, > > Olivier > > 2015-06-17 16:03 GMT+02:00 enricofer <enrico...@gmail.com>: > >> Hi Olivier, >> In your case, I think that the best way to do this is to create a view >> from the sql query and load it as layer, than, when qslider changes, change >> the view definition with "ALTER VIEW" and reload the layer. >> >> Regards, >> >> Enrico Ferreguti >> >> Il giorno 17/giu/2015, alle ore 14:29, olivier [via OSGeo.org] <[hidden >> email] <http:///user/SendEmail.jtp?type=node&node=5211452&i=0>> ha >> scritto: >> >> 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 >> >> _______________________________________________ >> Qgis-developer mailing list >> [hidden email] <http:///user/SendEmail.jtp?type=node&node=5211424&i=0> >> http://lists.osgeo.org/mailman/listinfo/qgis-developer >> >> ------------------------------ >> If you reply to this email, your message will be added to the >> discussion below: >> >> http://osgeo-org.1560.x6.nabble.com/Change-the-query-of-a-query-layer-postgis-tp5211424.html >> To unsubscribe from Quantum GIS - Developer, click here. >> NAML >> <http://osgeo-org.1560.x6.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml> >> >> >> ------------------------------ >> View this message in context: Re: Change the query of a query layer >> (postgis) >> <http://osgeo-org.1560.x6.nabble.com/Change-the-query-of-a-query-layer-postgis-tp5211424p5211452.html> >> Sent from the Quantum GIS - Developer mailing list archive >> <http://osgeo-org.1560.x6.nabble.com/Quantum-GIS-Developer-f4099106.html> >> at Nabble.com. >> >> _______________________________________________ >> Qgis-developer mailing list >> Qgis-developer@lists.osgeo.org >> http://lists.osgeo.org/mailman/listinfo/qgis-developer >> > >
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