Knockout validation on my dropdown don't work

Question

I work on a asp.net mvc project with the durandal template + breeze.

I would like to define validation logic on my view for adding/editing operations.

So far

Answer 1

Just stumbled into this one as well and after some trial and error I found the following:

The validation breaks down because the optionsCaption uses undefined as a value.

Your model apparently uses '' (in my case it was null) Since null != undefined it somehow all breaks down.

Knowing this, there are two solutions:

1. on the Model set the value to undefined (in your example transport.category(undefined)) and make use of the optionsCaption like you're used to
2. add a custom empty selectItem yourself and skip optionsCaption (the solution you used)