Is there any example about how to create a virtual field and subsequently change the attribute of a non-virtual field without wiping out the virtual field? Both are required to be done in the Python Console.
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2Good question as I use Virtual Fields quite a lot. I also noticed the Field Calculator in QGIS Modeler doesn't have an option to insert virtual fields so it would be interesting to see how to achieve this via the console.– JosephApr 28, 2015 at 8:57
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1 Answer
When you have a variable layer that is a reference to a vector layer you need
to specify the field definition
add the new field with an expression
field = QgsField('twoTimesA', QVariant.LongLong) layer.addExpressionField(' 2 * "A" ', field)
You can now modify an attribute and when you query the layer next time the virtual field will be updated.
answered Apr 28, 2015 at 11:07
