I am looking for a way to implement conditional value mapping in QGIS. This means that the values available in attribute number 2 depend on the value provided in attribute 1.
If the user enters "agriculture" in attribute 1, for attribute 2 only "corn" or "wheat" will be available.
Instead, if the user enters "forest" in attribute 1, for attribute 2 only "pines" or "olives" will be available.
And so on...
Apparently this is not doable just using the QGIS widget expression builder, but I am not sure. Here's a screencast to help visualize. The problem is that if for "class" I pick other than "Agri_Field", for the "color_aggri" attribute the same possible values appear.