I want to populate a text field of a layer with a set of predefined attributes in QGIS 3.4.
For example, The field name is Type. The attributes set are AAA, BBB , CCC. I want to limit the entry of this field to the attribute sets so only one of these attribute can be entered in this field.
How can I limit the value of this field to the predefined attribute sets so that the user can enter them without typing?