I have a calendar view that display 2 fields : a Many2one (user_id) and a Many2many (product_ids). 

    <!-- reservation calendar view -->                                                          

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

            <field name="name">reservation.calendar</field>                                     

            <field name="model">hoc.reservation</field>                                         

            <field name="arch" type="xml">                                                      

                    <calendar string="Reservation Calendar"                                     

                            date_start="start_date"                                             

                            date_stop="end_date"                                                

                            color="product_ids"                                                 

                            display="[product_ids] - [user_id]">                                

                            <!--<field name="group_product_ids"/>-->                            

                            <field name="user_id"/>                                             

                            <field name="product_ids" />                                        

            </calendar>                                                                         

            </field>                                                                            

    </record>  

By default, the many2many field display the ids of the records. Can i display the names ? I have to use a widget for this  ?

Thanks.