I'm using QGIS 2.14. I have a field defined as a value relation (widget). I would like to show the value in the linked "value column" as a label in the map in stead of the value of the "key column". Is there a way to achieve this?
I found the answer myself. This should be the label-expression:
attribute(get_feature('VALUE_LAYER_NAME', 'KEY_FIELD', KEY), 'VALUE_FIELD')
VALUE_LAYER_NAME: the name of the layer having the value column (the linked layer)
KEY_FIELD: the name of the key column in the VALUE_LAYER_NAME
KEY: the name of the field in the layer you are labeling (the one with the value relation defined)
VALUE_FIELD: the name of the value column in the VALUE_LAYER_NAME