from odoo import models, api


class AccountInvoice(models.Model):
    _inherit = "account.invoice"

    @api.onchange('fiscal_position_id')
    def somko_update_tax(self):
        for line in self.invoice_line_ids:
            line._onchange_product_id()

from odoo import models, api


class AccountInvoice(models.Model):
    _inherit = "account.invoice"

    @api.onchange('fiscal_position_id')
    def somko_update_tax(self):
        for line in self.invoice_line_ids:
            price = line.unit_price
            line._onchange_product_id()
            line.unit_price = price

Fix loss of unit price if edited
Fix loss of unit price if edited

  from odoo import models, api
  
  
  class AccountInvoice(models.Model):
      _inherit = "account.invoice"
  
      @api.onchange('fiscal_position_id')
      def somko_update_tax(self):
          for line in self.invoice_line_ids:
+             price = line.unit_price
              line._onchange_product_id()
+             line.unit_price = price
  
Fix loss of unit price if edited
## Code Before:
from odoo import models, api


class AccountInvoice(models.Model):
    _inherit = "account.invoice"

    @api.onchange('fiscal_position_id')
    def somko_update_tax(self):
        for line in self.invoice_line_ids:
            line._onchange_product_id()

## Instruction:
Fix loss of unit price if edited
## Code After:
from odoo import models, api


class AccountInvoice(models.Model):
    _inherit = "account.invoice"

    @api.onchange('fiscal_position_id')
    def somko_update_tax(self):
        for line in self.invoice_line_ids:
            price = line.unit_price
            line._onchange_product_id()
            line.unit_price = price
