hello, Dynamo developers. I just find error in automatic placing cable tray support node FamilyInstance.ByCurve return null Despite the support family type is line base Can I have some technical support? Thanks a lot.
I guess it will be very hard for people to help you without seeing more of your graph 
.
My guess now is you have the wrong input / types for curve and / or level.
I did a quick test. It is working for me.
Are you sure your Family is just Line Based and not Face Bases too or something?
Thank you very much for all your efforts.
I’m sure my family is line based can you share your line-based family with me for test, or I should convert line to curve.
It is easier if you share your Family and your .dyn.
ABG_GEN_Unistrut-Hanger_R20.rfa (512 KB)
I did a quick test and it is working for me.
I used Walls instead of Cable Trays because that was quicker for me.
Do you have a small sample project too maybe. With a few Cable Trays set up?
PS
Why are you doing this?
to exclude any empty list
That is not really how you exclude an empty list AFAIK.
But maybe it works for how you set up your graph.
Like that you get an item at an index.
I did to accelerate my work cable_trays input contain many empty lists in my case so I choose the items in list [0]
Look what happens if your are doing it that way.
Not Working list[0].
Working list
Summary
Fix the input for your Levels 
.
It’s a lot easier if you share a full screenshot of your graph, with all node preview bubbles pinned, so we can see exactly what’s happening - use Export as Image. Otherwise, we have to chase down answers to get to the same page.
I don’t get it you mean remove list[0] but it still returns null
You still haven’t shown any of the node preview bubbles (so we can see your data and structure) and you’re zoomed out too far to where the node titles are now hidden and we don’t know what nodes you’re using. Please make sure you’re following the instructions from the linked thread on exporting your workspace.
No, not remove list[0] but try list instead for your Levels so have a list
with Levels (and indices) instead of a single Level (without an index).
The Level input for FamilyInstance.ByCurves needs a list it looks like.
I agreed with @Nick_Boyts on this.
Especially for future post.
That being said.
I am pretty sure Levels not being
a list is the issue.
Again, look at the difference.
List[0]
List
Maybe someone else can explain this better?
