QGIS » QGIS Application

OK you are right when you load the layer via standard PostGIS loader in GUI. I load the layer via Python Script with the following lines:

... snip

      uri = [[QgsDataSourceURI]]()
      uri.setConnection(hostname, port, dbname, username, "")
      uri.setDataSource(schema, table, geom_col, "")
      vlayer = [[QgsVectorLayer]](uri.text(), layerName, "postgres")        

      canvas = self.iface.getMapCanvas()
      [[QgsMapLayerRegistry]].instance().addMapLayer(vlayer)

snip ...

Try to load a layer with insufficient permissions. You will get a different message box (white with PostgreSQL error message). After click on OK QGIS crash.

After creating an instance of a layer, you must ensure that vector layer is loaded correctly - if not, further behaviour is undefined.

if not vlayer.isValid():
  print "Couldn't load layer!" 

wonder thank you for the workaround. Isn't it better to ensure the correct load of the layer at the provider?

Well, this check is not really a workaround, it's the thing you have to do always when loading a layer. The problem here is that all the initialization happens in constructor and constructors can't return any value to tell you whether the initialization went fine, so you need to call isValid() to find it out. Once we will be free to do some bigger modification to QGIS API it's likely that this will be changed somehow.

However it's true that QGIS shouldn't crash even if you're trying to access invalid layer.

Martin

Milestone Version 0.9.1 deleted