how convert a datetime field and compare with current date?

hi

I want to write a search view and define a filter in it, that compare "created_date" with "current date" and show all of requests that created today.

problem1: how write filter that get only date from "create_date" (because this field is datetime format)

problem2: how compare with current date?

<record id="support_services_view_search" model="ir.ui.view">

....

<filter name="today" string="Today" domain="[('??(how get date)???create_date','=',???]"/>

thanks