Following on from this question: How to turn on/off all labels of all layers in QGIS, OP mentioned in his comment that he uses rule-based labels. I tried searching online as to how these types of labels could be read and modified but only managed to find this post from lutraconsulting:
In order to facilitate addition of rule-based labelling, some internal changes were made to the QGIS labelling engine interface. The labelling is now driven by the new class
QgsLabelingEngineV2which may have several label providers associated with it.
Sounds great. However, when reading through the QgsLabelingEngineV2 class, it mentions:
this class is not a part of public API yet.
Is it currently possible to control rule-based labelling using python?