# Filter walls by base constraint

**URL:** <https://forum.dynamobim.com/t/filter-walls-by-base-constraint/11492>\
**Category:** Revit\
**Created:** [May 3, 2017, 7:29am UTC](https://forum.dynamobim.com/t/filter-walls-by-base-constraint/11492 "2017-05-03T07:29:52Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![filippoperon88](https://avatars.discourse-cdn.com/v4/letter/f/cab0a1/32.png) [@filippoperon88](https://forum.dynamobim.com/u/filippoperon88)\
**Post date:** [May 3, 2017, 7:29am UTC](https://forum.dynamobim.com/t/filter-walls-by-base-constraint/11492/1 "2017-05-03T07:29:52Z")

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Hi, i’m at the beginning of using dynamo.  
I want to select all walls of my model, by a value parameter ( base constraint-----\> name " ST-0 - Fondazioni". I tried to do as explained in this post  
[https://forum.dynamobim.com/t/select-elements-by-parameter/6371](https://forum.dynamobim.com/t/select-elements-by-parameter/6371)

but don’t work for me because it seems select all wall of my model  
 ![](https://cdck-file-uploads-us1.s3.dualstack.us-west-2.amazonaws.com/flex022/uploads/dynamobim/original/3X/f/b/fbde35f7f79ad80447f117c5d9191dab6691356e.png)

Someone can help me please ?  
Many thanks

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**Author:** ![filippoperon88](https://avatars.discourse-cdn.com/v4/letter/f/cab0a1/32.png) [@filippoperon88](https://forum.dynamobim.com/u/filippoperon88)\
**Post date:** [May 3, 2017, 8:15am UTC](https://forum.dynamobim.com/t/filter-walls-by-base-constraint/11492/3 "2017-05-03T08:15:49Z")

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Thank you for answer. But still not work 😞

 ![](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/a/c/acef160493d32604d1f0637252e9254fe9af1e53.png)

again, it show me all walls of my model.  
And then, how i can select the elements on list, inside revit environment ?

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**Author:** ![Ritesh\_Chandawar](https://avatars.discourse-cdn.com/v4/letter/r/f05b48/32.png) [@Ritesh\_Chandawar](https://forum.dynamobim.com/u/Ritesh_Chandawar)\
**Post date:** [May 3, 2017, 8:23am UTC](https://forum.dynamobim.com/t/filter-walls-by-base-constraint/11492/4 "2017-05-03T08:23:53Z")

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@filippoperon88 Can you show me the preview of your == node? I suspect there is no **True** in that list and that is the reason you are getting **Empty List** on your **List.FilterByBoolMask** node.

Another question is what you mean exactly when you said: “how i can select the elements on list, inside revit environment ?”

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**Author:** ![filippoperon88](https://avatars.discourse-cdn.com/v4/letter/f/cab0a1/32.png) [@filippoperon88](https://forum.dynamobim.com/u/filippoperon88)\
**Post date:** [May 3, 2017, 8:56am UTC](https://forum.dynamobim.com/t/filter-walls-by-base-constraint/11492/6 "2017-05-03T08:56:55Z")

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i attached the file

[wall\_filter.dyn](https://forum.dynamobim.com/uploads/short-url/jtAAFXlzhTDHlbDcZuprhPouaYW.dyn) (4.9 KB)

for your question:  
i want to filter in revit inside a view, the walls from a value parameter, how i can select it after i run the graph ? ( sorry for my english 😳)