Hello!
I'm using Odoo12 and for the first time i made a custom module.
I added new fields to a view (stock.picking) without issues, now i want to have the value of my fields when i print related report (stock.report_deliveryslip).
I tried several times without success. Can someone help me?

My module has: 

1.  models.py

2. views.xml

3. stock_report_deliveryslip_inherit.xml

I think my problem is in stock_report_delivery_inherit, i can print some text but i can't do it for the value of my custom field.

Thanks for your attention!

1. models.py

from odoo import models, fields, api
class StockPickingInherit(models.Model):
    _inherit = 'stock.picking'

    a_field = fields.Char(string='a text', store=True)
    b_field = fields.Char(string='b text', store=True)
    c_field = fields.Char(string='c text', store=True)

views.xml

<odoo>
 <data> <record id="stok_picking_inherit" model="ir.ui.view"> <field name="name">stock.picking.inherit</field> <field name="model">stock.picking</field> <field name="inherit_id" ref="stock.view_picking_form"/> <field name="arch" type="xml"> <xpath expr="//field[@name='carrier_id']" position="after"> <field name='a_field'/> </xpath> <xpath expr="//field[@name='carrier_id']" position="after"> <field name='b_field'/> </xpath> <xpath expr="//field[@name='carrier_id']" position="after"> <field name='c_field'/> </xpath>   </field> </record> 
</data> </odoo>

stock_report_delivery_inherit.xml

<odoo> <template id="stock_report_delivery_inherit" inherit_id="stock.report_delivery_document"> <xpath expr="//table[@class='table table-sm']" position="after"> <div class="row mt32 m32" id="test_inherit"> <div class="col-auto mw-100 mb-2"> 
<h3>INFO: </h3> 
<strong>One: </strong> <!-- "a_field" value-->
<strong>Two </strong> <!-- "b_field" value-->
<strong>Three: </strong><!-- "c_field" value-->

				</div>
			</div>
		</xpath>
	</template>	
</odoo>