# C# Dropdown

**URL:** <https://forum.dynamobim.com/t/c-dropdown/17503>\
**Category:** Revit\
**Created:** [December 15, 2017, 3:25pm UTC](https://forum.dynamobim.com/t/c-dropdown/17503 "2017-12-15T15:25:00Z")\
**Posts on this page:** 1\
**Showing post:** 12

<div class="post-metadata">

**Author:** ![Anton\_Huizinga](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/anton_huizinga/32/155377_2.png) [@Anton\_Huizinga](https://forum.dynamobim.com/u/Anton_Huizinga)\
**Post date:** [January 29, 2021, 8:25am UTC](https://forum.dynamobim.com/t/c-dropdown/17503/12 "2021-01-29T08:25:20Z")

</div>

“Next week” was a bit optimistic but finally I was able to do some testing. And I got result.

There are two things you should know:

1. It seems not possible to combine UI and Zero Touch nodes in one DLL so you need to use a seperate Solution to build dropdown nodes.

2. It only works if the DLL is loaded via a package, not with the ‘import library’ function.

You can download a sample Visual Studio Solution below (without de compiled DLL file). Two classes are available. One to create a dropdown that returns the name of a Tin Surface as a string and one to create a dropdown that outputs the Tin Surface as object. In Dynamo it looks like this:

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/a/2/a29c55a46ec21f422966efe058a4bfbc74d60cfc.png)

After building a release DLL you need to create a package, you can do via de Dynamo Package menu:

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/7/c/7c4265565591f41f5ca35c67641282fd3ed2016c.png)

Do publish locally, not online! After that the dropdown nodes appear in the category list.

You can download the sample code here:

[Sample code, VS Solution, no DLL, zipped](https://url.huiz.net/dyndropdn)

Good luck and happy coding! Hope it will help someone!

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