I am using "Unique Values" widget with "Editable" option in QGIS 2.18.3, for my "Name" field in POIs layer to eliminate spellings mistake.
"Unique Values" widget fetches all the distinct values in a drop-down list which matches with your text string from the layer.
Now I need a solution to fetch values only within the specific buffer of a newly added point. I mean, when I add new feature point it should fetch values within 30 meters buffer of my point, matching with my text string.
I need this solution to eliminate duplication with existing data which is very common in our Data Entry case. Is it possible to use some "Expression" in "Constraint" option?