Parameter.GetValue node failing

Hello everyone,

I am having an issue with this node from the Orchid package. It works great on occasion, but other times it returns a null.
Brief story:

I am background opening a bunch of Revit .rfa files based on a user input, then trying to extract the parameter values (Among other things) from the family and write it to excel. All other extracts are working, from formulas to groups, to types, to display units etc.
The values however report the issue above at the Parameter.GetValue node. This only happens sometimes which is what I don’t understand. I have run it on other family folders and everything gets extracted perfectly with the values and everything else, but occasionally I get this error and the excel file contains a null value represented vertically in a column. I have tried to put start/end transaction node’s in place, but the error persisted.
Can any one direct me or offer any advise into what I should be looking at to get this sorted. I am struggling to find the solution myself. I thought it might have something to do with the way the families are constructed, but I haven’t been able to prove that.
Also, am I going about this task the right way or is there an easier approach?

Thanks in advance for your time.

At my first look, You are using “Pass through” node in wrong way.
The node let you can control the order of nodes to run in your graph,
for example, you may want to create a wall then place a door at the wall in one Dynamo graph, in this case the door can’t be placed before creation of the wall. ‘Pass Through’ node is the one to be used in this case. Passthrough node will wait the created walls to input at ‘wait for’, after walls arrive at the node, then it will pass through the original data about door placing(before placement) which is connected at ‘pass through’ and then you can place a door with the data.
In your graph, there is no difference without the node because you connected the same data at both ‘pass through’ and ‘wait for’.

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Yes looks like you use passtrough wrong way, but i think in that case it will give you output anyway…could you show what passtrough after the family parameter properties give you…another thing where did the node parameter get value comes from ? is it Orchid ? if so its very importent to feed in orchidtypes, both for document and familytypes

Hi there,

Thanks for the response!

The Passthrough node doesn’t seem to have much of an effect on the outcome, as this node still produces the required info the way that it is wired. My thinking was that I wanted to open the files before I extracted the parameters from the family. Should I do this in another way?

Here is the list from the Passthrough node after the FamilyParameter.Properties node. it is a list of all the parameter names of each family in the folder location, and that works well.

In this example I have run the script on the “Doors” metric family folder that ships with the Revit software. Here you can see the results of the Excel file and this is where my problem is. It will produce correct values for most of the families in the folder, just not all of them.

Here you can see that column B gives me the parameter values where those values exist.

In this instance, it just reports null… The strange thing for me is that there is no difference I can see in this family as opposed to the one that is working correctly.


I responded to both questions in the response I gave above :slight_smile:

In a nutshell what I am trying to do is extract the parameter values of these families which are located inside a folder, without having to open them up one at a time. Is there perhaps an easier way to do this?

Another option could be open an empty project load all the families in there and the do the job…instead of background open every single family

Hi Sovitek,

That is what we are trying to avoid, we are trying to make it so that we don’t have to load any families anywhere, just extract the parameter values directly from the family document without loading or placing the family. Do you know if this is actually possible?

yes it should be possible with background open but again if you BO many families it isnt so stable as the way i mention above, just my experience :wink:

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Thanks for your help with this, maybe I’ll look at a different way then :slight_smile:

ok if you find a better way please share it here…good luck

You’ll be best served here probably with python if you have lots of families. I have read and wrote hundreds of families that way accurately in lieu of nodes.

Keep in mind that if you load them, they may grab junk from the project they are loaded into so don’t save I’d you don’t want that.

Thanks Sean, I wish I knew Python better than I do, then I could save countless hours everywhere I’m sure.
I will try find pieces of code and put it together as best as possible, thanks!

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May start here and see if you can work it to do what you want.


Thank you very much Sean, I will see if I can adapt it to my needs, appreciate the help! :slight_smile: