How to fix Ajax file validation in yii2?

Question

Yii

I'm stuck, urgently need advice.
Ajax validation does not pass the file, respectively for the file validator 'skipOnEmpty' =>true
And what about the required? Because it returns an error. Usually I somehow bypassed this in circles, but for sure there is an adequate method.
For now, the bike is on my mind. What would be in the ajax request to add a sign of the existence of a file. I use kartik fileinput, got into the docks in an attempt to find an implementation of this, but somehow to no purpose so far.