sale_view.xml

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

<!--
    Copyright (C) 2014-2015 Akretion (http://www.akretion.com/)
    @author Alexis de Lattre <alexis.delattre@akretion.com>
    The licence is in the file __openerp__.py
-->

<openerp>
<data>


<record id="view_order_form" model="ir.ui.view">
    <field name="name">sale_rental.view_order_form</field>
    <field name="model">sale.order</field>
    <field name="inherit_id" ref="sale_start_end_dates.view_order_form" />
    <field name="arch" type="xml">
        <xpath expr="//field[@name='order_line']/form//field[@name='start_date']" position="before">
            <field name="rental_type"
                attrs="{'invisible': [('rental', '=', False)], 'required': [('rental', '=', True)]}"/>
            <field name="extension_rental_id"
                attrs="{'invisible': [('rental_type', '!=', 'rental_extension')], 'required': [('rental_type', '=', 'rental_extension')]}"
                domain="[('rental_product_id', '=', product_id), ('state', 'in', ('ordered', 'out'))]" />
            <field name="sell_rental_id"
                attrs="{'invisible': [('can_sell_rental', '=', False)]}"
                domain="[('rented_product_id', '=', product_id), ('state', '=', 'out')]"/>
            <field name="rental" invisible="1"/>
            <field name="can_sell_rental" invisible="1"/>
        </xpath>
        <label for="product_uom_qty" position="before">
            <field name="rental_qty" attrs="{'invisible': [('rental', '=', False)], 'required': [('rental', '=', True)]}"/>
        </label>
    </field>
</record>

<record id="view_order_form_sale_stock" model="ir.ui.view">
    <field name="name">sale_rental.sale_stock.view_order_form</field>
    <field name="model">sale.order</field>
    <field name="inherit_id" ref="sale_stock.view_order_form_inherit" />
    <field name="arch" type="xml">
        <xpath expr="//field[@name='order_line']/form//field[@name='product_id']" position="attributes">
            <attribute name="on_change">product_id_change_with_wh_with_rental(parent.pricelist_id, product_id, product_uom_qty, product_uom, product_uos_qty, False, name, parent.partner_id, False, True, parent.date_order, product_packaging, parent.fiscal_position, False, parent.warehouse_id, rental_type, rental_qty, context)</attribute>
        </xpath>
        <xpath expr="//field[@name='order_line']/form//field[@name='product_uom_qty']" position="attributes">
            <attribute name="on_change">product_id_change_with_wh_with_rental(parent.pricelist_id,product_id,product_uom_qty,product_uom,product_uos_qty,False,name,parent.partner_id, False, False, parent.date_order, product_packaging, parent.fiscal_position, True, parent.warehouse_id, rental_type, rental_qty, context)</attribute>
        </xpath>
        <xpath expr="//field[@name='order_line']/form//field[@name='product_uos_qty']" position="attributes">
            <attribute name="on_change">product_id_change_with_wh_with_rental(parent.pricelist_id,product_id,product_uom_qty,product_uom,product_uos_qty,False,name,parent.partner_id, False, False, parent.date_order, product_packaging, parent.fiscal_position, True, parent.warehouse_id, rental_type, rental_qty, context)</attribute>
        </xpath>
    </field>
</record>

</data>
</openerp>