"Null" value in Dynamo

Hi all, I have a question about the value type I came across(maybe I shouldn’t call it “null”). Basically what I’m trying to do here is filtering out the curtain panels by parameter. In this case, MULL_TRANS_VIS is a visibility parameter, if it’s checked, then it’ll return 1, else it will be 0. But for those panels don’t have this visibility parameter, it just returns nothing(as shown below), it’s not “null” value nor empty list, and these panels without the parameter are actually something I’d like to filter out. So what exactly this value type is and is there anyway to filter this thing out? Any thought? Thanks!

You could try filtering with an == node and {1,0} followed by a List.AnyTrue (Clockwork) node

Hi Sol, thanks for your reply. I understand your method and it works fine in this case. However, I’m still wondering what the value type this “null” is and how Dynamo handle this situation when there’s no such parameter.

For example, if the parameter value I’m looking for is not true/false but numbers, say panel spandrel area, I’d like to know which panel doesn’t have this parameter(meaning no spandrel). In this case, I can not just using 0 or 1 to test, actually I’ve no idea how to test because the spandrel area can be all different.

Well, I guess I sort of figured out what it is. It turns out to be a string type with empty value. So now I can filter them out if the panel doesn’t have the parameter I’m looking for.

My guess is that it is a blank string. Try searching for “” or " " (the second one has a space in the quotes)

Personal thought it should be null since the parameter does not exist but dynamo does not like nulls.

Hi Steven, you’re right. It’s a blank string (without space). See the screenshot in my previous post.

There’s this guy too, Object.IsNull but it only gives a true/false output. Can pair it to a list and split your results.