Empty 'From Room' value causing error ...?

I’m trying to extract Door-Room information from Revit to Excel. I’m getting an error ‘Warning: Internal error, please report: Dereferencing a non-pointer’ from the ‘fromRoom’ ‘Room.Number’ & ‘Room.Name’. I think it maybe because the external doors don’t have a Room from (as it’s working fine with to Room).

Can anybody help? I’m fairly new to Dynamo and I need this in a panic for my final year college project. I suspect I need to put an ‘if’ condition in to tell it to replace an empty value with a specified value…?? How would I do that though?

Hi @thomas_garvin

That’s because you have null values in your list. You can fix this issue by replacing null values by a string “None”. See below.

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Kulkul thank you very much for that

I wonder could you help me out again? I haven’t been able to pull out parameter values from the ‘ReplaceByCondition’ node. I’ve tried various methods including Element.GetParameterValueByName but to no avail, it just reports a function.