I am required to display a QMessageBox.warning() as a reminder to update a specific field when "Toggle editing" is clicked. This is required for a project in QGIS. Currently, I just can display the QmessageBox to notice which layer is active
from PyQt5.QtWidgets import QMessageBox
from qgis.core import QgsProject
layer=qgis.utils.iface.mapCanvas().currentLayer()
QMessageBox.warning(iface.mainWindow(), "Capa Activa", 'La capa activa es ' +layer.name())
Best Answer
You need to "connect" your function to the signal
beforeEditingStarted
belonging to the QgsVectorLayer class. https://api.qgis.org/api/classQgsVectorLayer.html#a817d41d8320a54b2d51fbcb54e7fe2dd