Openerp 6.1：在销售订单行中显示日期范围

Question

我试图在sales.order.line的搜索部分显示日期范围，即“date from”和“date to”，但它不会显示它。我在下面附上了我的代码。我错过了什么：

班级代码：

from osv import fields, osv
class sales_invoice_date(osv.osv):
_name='sale.order.line'
_inherit='sale.order.line'
_columns={
    'ordered_date': fields.related('order_id', 'date_order', type='date',    relation='sale.order', select= 1, string='Date Ordered'),
    'due_date_from':fields.function(lambda *a,**k:{}, method=True, type='date',string="Due date from"),
    'due_date_to':fields.function(lambda *a,**k:{}, method=True, type='date',string="Due date to"),

}
sales_invoice_date()

查看代码：

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>

    <record id="view_sale_orderlinedate" model="ir.ui.view">
        <field name="name">sale.order.line.dateinherit</field>
        <field name="model">sale.order.line</field>
        <field name="type">tree</field>
        <field name="inherit_id" ref="sale.view_order_line_tree"/>
        <field name="arch" type="xml">
            <field name="order_id" position="after">
                        <field name="ordered_date" />
                        </field>
            </field>

    </record>

    <record id="view_sale_orderlinedate2" model="ir.ui.view">
        <field name="name">sale.order.line.dateinherit2</field>
        <field name="model">sale.order.line</field>
        <field name="type">search</field>
        <field name="inherit_id" ref="sale.view_sales_order_uninvoiced_line_filter"/>
        <field name="arch" type="xml">


            <field name="product_id" position="after">
                        <field name="ordered_date" />
                        <field name="due_date_from" filter_domain="[('date_due','&gt;=',self)]"/>
                        <field name="due_date_to" filter_domain="[('date_due','&lt;=',self)]"/>
          </field>
          <field name="salesman_id" position="after">  
                        <field name="due_date_from" filter_domain="[('date_due','&gt;=',self)]"/>
                        <field name="due_date_to" filter_domain="[('date_due','&lt;=',self)]"/>
          </field>
        </field> 
    </record>

    </data>
</openerp>