I am trying to do something based on whether or not the struct input on my UFUNCTION BP node pin is connected or not. I looked in documentation for USTRUCT, and didn’t see much to help me, any ideas?
You can do this if you derive a custom node (basically your own version of one of the many UK2Node_xxx classes in the engine). However that is much more involved than just exposing a standard UFUNCTION.
Otherwise the only thing you might be able to do is give your C++ struct parameter a default argument with some special values that you could check for inside the function, to see if the default was used. However I can’t remember off hand if UHT actually allows default arguments for structs. If not, I guess you could maybe just set up your structs constructor to assign values you could test for.