avoid adding an output if it is empty

Discussion created by toreb-geodata-no-esridist on Apr 26, 2010

I have a model which analyses best paths to make roads.

I have two parameters set as "add to display". The first makes a route polyline for a suggested road.

The second adds the same polyline but with a different symbology. this output is only populated if the calculated road crosses a steep slope  (which will only happen if there are NO alternative routes around the steep slope within the study area)

In most cases, the calculated road does not cross such slopes, but still the model creates the layer for roads crossing steep slopes in any case (which will be an empty layer when the road is "ok"). Is there some way to only add this 2nd output to map if it contains data?

added parts of the model. Parameter to the left is always drawn, that is the road. Parameter to the right only contains data if the suggested road crosses a steep slope