Hi,

So you have defined the new Char field in product.product right?

Then one option is to define a new related field in sale.order.line. And call that related field, like Yenthe described above.

Hope you are working v8.

For eg:

in your py file:

class sale_order_line(models.Model):

    _inherit = 'sale.order.line'
    
    new_field = fields.Char(related='product_id.your_field', string='New Field')

in your xml file, like Yenthe told:

<record id="view_order_form_inherit" model="ir.ui.view">
      <field name="name">sale.order.form.inherit</field>
      <field name="model">sale.order</field>
      <field name="inherit_id" ref="sale.view_order_form"/>
      <field name="arch" type="xml">
        <xpath expr="//tree[@string='Sales Order Lines']/field[@name='name']" position="after">
             <field name="new_field"/>
         </xpath>
      </field>
    </record>

In Odoo/OpenERP we can inherit or use existing modules object/class/model and views. We can also inherit single field of existing modules. The question is why we need such inheritance.

The purpose of inheritance or why we need inheritance is given below:

1. To change attributes of some fields which exists on existing/custom model (e.g. making fields readonly,invisible)

2. To add/modify/delete old or new fields in existing/custom model (e.g. Product, Sales, HR, Fleet Management, Attendance modules model etc)

3. We can also add buttons in already existing/custom model (form and tree) view by using inheritance

Get .py and .xml code from here:

http://learnopenerp.blogspot.com/2018/01/inheritance-in-models-and-views.html