I want to set the user search field by default to user_id in CRM - Logged Phone Calls...please advice.

<search string="Search Phonecalls"> <filter icon="terp-go-today" string="Today" domain="[('date','<', time.strftime('%Y-%m-%d 23:59:59')), ('date','>=',time.strftime('%Y-%m-%d 00:00:00'))]" name="today" help="Todays's Phonecalls"/> <filter icon="terp-go-week" string="7 Days" help="Phonecalls during last 7 days" domain="[('date','>=',(datetime.date.today()-datetime.timedelta(days=7)).strftime('%Y-%m-%d'))]"/>

<separator orientation="vertical"/> <field name="name"/> <field name="partner_id"/> <field name="user_id"> <filter icon="terp-personal-" domain="[('user_id','=',False)]" help="Unassigned Phonecalls"/> </field> <field name="section_id" widget="selection" string="Sales Team"> <filter icon="terp-personal+" groups="base.group_extended" domain="['|', ('section_id', '=', context.get('section_id')), '|', ('section_id.user_id','=',uid), ('section_id.member_ids', 'in', [uid])]" help="My Sales Team(s)"/> </field> <newline/> <group expand="0" string="Group By..."> <filter string="Partner" icon="terp-partner" domain="[]" context="{'group_by':'partner_id'}"/> <filter string="Responsible" icon="terp-personal" domain="[]" context="{'group_by':'user_id'}"/> <separator orientation="vertical"/> <filter string="Creation" icon="terp-go-month" help="Creation Date" domain="[]" context="{'group_by':'create_date'}"/> <filter string="Date" icon="terp-go-month" domain="[]" context="{'group_by':'date'}" help="Date of Call"/> </group> </search>