I am writing a python processing script in QGIS 3. In it, I have polygon geometry objects stored in a list
polygonGeoms and I want to dissolve all of it into one geometry. However, when calling the function
QgsGeometry.unaryUnion(polygonGeoms), it returns a null geometry. I've used the
unaryUnion function before so I know that it should give me the result I want.
To investigate, I exported the geometries as a temporary shapefile layer. And when I use the
Dissolve tool in QGIS 3, it also returns a null feature. The
Dissolve tool works on the shapefile when I use QGIS 2.18 though, for some reason.