Hi,
If you need the information inside a report template, you can just add this line of code in the needed place:  len(doc.order_line)

Thanks

Hi,

from odoo import models, fields, api
class SaleOrder(models.Model):
    _inherit = 'sale.order'

    line_count = fields.Integer(string='Number of Lines',
                                compute='_compute_line_count')

    def _compute_line_count(self):
        for order in self:
            order.line_count = len(order.order_line)

the order_line length includes the section and note values 

Hope it helps