How to use the "Render Views filters as select list" option in an Entity Reference field? I have a content type Trait, that includes an Entity Reference field Trait Type. A trait type is categorized under a Trait Category. For my Trait content type form I  created an Entity Reference View for as follows:



As (if) you can see, I have included a contextual filter that takes Trait Category id values. I've also added a relationship for Trait Type and Trait Category. 

The view works as expected, when I enter trait category id values I'm able to filter related trait types. 

My difficulty comes when my I want to use this view as my datasource for a Entity  Reference field (Trait Types List) I want to add to my Trait content type form.In the field settings field for the Triat Types Entity Reference Field I've done the follow:



Now what I can't understand is:


What View Arguments is supposed to take and do I need to give it any value?
Shouldn't the option "Render Views Filter as a select List" a new select widget to my Trait content type form that would allow me to filter my Trait Type Entity Reference select widget?


Something like this perhaps:



Is my expectation wrong? How can I use this option?
1.  "Entity selection Views" helps you to deal with options list in the entity reference widget (on node add/edit form). E.g. if you want to reference some nodes that have specific term reference. Entity reference view can help you you.

As I see you want to reference "child" Trait nodes of special category to one "parent" Trait node. (At list your View shows it). In this case you don't have to use contextual filter. You can use ordinary "filter criteria" and set target category value.

2. "Render Views Filter as a select List" - it's not a widget for your content type add/edit form. But it's a widget for exposed filter in views. If you want to use this field as an exposed filter in views by default it's an autocomplete. But this option makes filter as select widget. If you read the "Render Views Filter as a select List" description, you might see that developers advice you not to use this option if you have more that 100 referenced entities. Just imagine a select widget with 100 options and query with WHERE condition. Just mind it.