How to fix null in the list of existing node

Im a newbie of dynamo and need somebody to help me out. I have created a simple geometry form in revit canvas to use in a dynamo node. but, there was a problem. when I open my dynamo and previous dynamo file, then I select again all geometry element in revit to dynamo node, but all the elements didnt show up in the list as expected and it was a Null as seen in the attachment link video…

how to solve this Null to make the list works as it should.


Easy. Press RUN and it will work;)

You have two option in Dynamo (left corner down) MANUEL and AUTOMATIC.

For bigger skripts Manual is a good option because your computer only calculate if necessary

Hi mate, unfortunately your suggestion to press RUN it doesn’t work for my case. I usually keep it automatically, but when I change to manual to press run as your suggestion there is no solve the null issue.
for your information, I previously only save dynamo file without saving existing revit project file at all. When I open another new revit project file and I try to reopen or use that dynamo file, it usually came with Null in the list and I even can not input any data again… I also try to get another new node on this same file, but that new node also come with null in the list too.

another case, I try again to save revit file with the dynamo file too, then I closed it both file… I reopen both file, in this dynamo I previously made a simple line, when I change the line number the length in revit background view didnt increase its length follow to dynamo. which step did i miss or wrong ?

Is everytime both revit and dynamo must save together and use it together?
Is any possibility to use one revit file with multiple different dynamo file at the same time?
is a dynamo file only can be used at it own existing revit file or used in any other revit file too?
because everytime if there is an error and I closed dynamo to reopen it then everything became null and always made me to redo everything from zero again and again, quite frustrated for me as new beginner :smile:

please advice me further, senior :slight_smile:

  1. Sometimes “SELECT MODEL ELEMENTS” didnt work after reopen. Don´t know the reason. I simple take a new , combine nodes and delete old one.

  2. It shows NULL if prozess didnt run before, nothing selected or input data is wrong. In your case you didnt select a element. Solution: Take new SELECT MODEL ELEMENTS

  3. You only can run 1 Dynamo Skript at time. For different Task its better to create two Dynamo Scripts.
    Tip: If you have to copy from another Script i use Dynamo Sandbox. You can open as much Script as you want but its not connected to Revit!!!

  4. Dynamo loose connection to Revit project if you close Revit. I´m not quite sure, but you can close Dynamo and reopen and connection should be still there. I dont got much and strong errors to reopen Revit so only close Dynamo in most cases. Maybe you can try Dynamo Player after your Skript is final where you only have to input your data.

  5. Dynamo is frustration sometimes. Dont forget its programming and you only learn from mistakes. But after achieving your goal you will be happy as fuck

in my case, I use a generic model to create element form, in select model element node, but im not sure it should used in generic model family or generic model adaptive ?

diroot t4c.dyn (671.0 KB)

this is the link of the tutorial I learn from… (please see in 56:23 , in this tutorial it seem he was creating the revit form in generic model canvas, right? but, why his one has no problem in that modelcurve not as I did.

please help me out of my doubt, thanks

1 Like

You can use “ModelCurve.ReferenceCurveByCurve” only in Revit Familys instead of Project (video 42min).
The Problem is that this typ of method creates special lines which are only available in Familiys.

test1.rfa (1.2 MB) test1.dyn (661.7 KB)
In Revit is the Projekt file and also different Family file types. In AutoCAD you sort geometry to Layers. In Revit/BIM we use Families. Its a little bit different and sometimes frustrating. If you dont know which Family you should use - take “GENERIC MODEL” you can switch it later to another one. If you great special or complex geometries you can use a special one: “Metric Generic Model Adaptive.rft”.

Open a new Family and draw your green lines there and restart your Revit-Script in that family. Worked for me.

btw. you can unable unecessary nodes by rightclick -> freeze
This will increase your process time.

yes, it is working for me now… :slight_smile: thanks again
I try to use adaptive family, bcoz in this freeform if using generic model family will get a warning message in form.byloftcrosssection said that this family type can not use. anyway, just want to confirm,
if using adaptive family or any other family should I always create geometry model in ref. level canvas, right? bcoz when I open adaptive family the default canvas is a 3dview and any geometry which is create there will not be allowed to select in the node, am I right?

i got that warning too in some familys. Don´t know why cuz i changed crosssection and warning wasnt there anymore.

i dont know where you should draw crosssection. Think XY Plane, but you dont have to.