[Qgis-developer] Re: cannot call QgsVectorDataProvider.changeGeometryValues() from python

[Bob English]

Hi,

See https://github.com/EcoGIS/CAPS-Scenario-Builder to download lots of well
commented python code.

See http://qgis.org/pyqgis-cookbook/index.html

This code works for me.  I'm using the 1.71API and my app is a desktop app
rather than a plugin.

feat = QgsFeature()
roundPointGeom = None
while provider.nextFeature(feat):
                point = feat.geometry().asPoint()
                roundPointGeom =
QgsGeometry.fromPoint(QgsPoint(round(point.x(), 2), round(point.y(), 2)))
                provider.changeGeometryValues({feat.id(): roundPointGeom})

and

elif vlayer.geometryType() == 1: # line
            while provider.nextFeature(feat):
                roundedLine = []
                line = feat.geometry().asPolyline()
                for point in line: 
                    roundedLine.append(QgsPoint(round(point.x(), 2),
round(point.y(), 2)))
                    provider.changeGeometryValues({feat.id():
QgsGeometry.fromPolyline(roundedLine)})
 

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