I'm working with Odoo 16 and have encountered a problem with linking two models and handling _unknown values. Specifically, I have two models: nkap_custom_paiement and account.payment.register. The former is a custom model inheriting from account.payment, and the latter is a TransientModel used for payment registration.

Models Overview: nkap_custom_paiement (Inheriting account.payment)

Has a field related_payment_id that links to account.register.payment. Handles payment approvals and has methods like action_cashier_approval to perform actions on linked payments. CustomPaymentRegister (Inheriting account.payment.register)

Handles the creation of account.payment records and sets the related_payment_id to link back to the wizard.

I am trying to add an approval process to the payment that are register throught the wizard then after the approval it should called back the initial method on the wizard(thats why i need to store id)

# -*- coding: utf-8 -*-

from odoo import models, fields, api, _
from odoo.exceptions import ValidationError, UserError
import re


class nkap_custom_paiement(models.Model):
    # _inherit = 'account.payment'
    _inherit = ['account.payment']

    related_payment_id = fields.Many2one('account.register.payment', string='Related Wizard')
    state = fields.Selection([
            ('draft', 'Drafted'),
            ('waiting_approval', 'Waiting Approval'),
            ('approved', 'Approved'),
            ('rejected', 'Rejected'),
            ('posted', 'Posted'),
        ], string="Approval Status",default='draft')

    DFC_approver_sign = fields.Binary('DFC Signature')
    DG_approver_sign = fields.Binary('DG Signature')
    current_approval = fields.Selection([('1', '1'), ('2', '2'), ('3', '3')], string="Is Current Approver")

    
    def action_submit_for_approval(self):
        company_id=self.env.company
        self.write({'state': 'waiting_approval'})       
        message = "Vous avez un paiement pour la 1ere approbation"
        self.current_approval = '1'
        self.activity_schedule('purchase_order_approval.mail_activity_data_approval', user_id=company_id.po_third_approver_ids.id, note=message)
        self.env['bus.bus']._sendone(company_id.po_third_approver_ids.partner_id, 'simple_notification', {'title': _("Information"), 'message': message})


    def action_DFC_approval(self):
        company_id=self.env.company
        if self.env.user.id in company_id.po_third_approver_ids.ids:
        
            self.current_approval = '2'
            self.write({'state': 'waiting_approval'})
            self.DFC_approver_sign = self.env.user.user_signature
            message = "Vous avez un paiement pour la 2ere approbation "
            self.activity_schedule('purchase_order_approval.mail_activity_data_approval', user_id=company_id.po_DG_approver_ids.id, note=message)
        else:
            raise ValidationError(_("Seul %s peut approver !"% company_id.po_third_approver_ids.id ))

    def action_DG_approval(self):
        company_id=self.env.company
        if self.env.user.id in company_id.po_DG_approver_ids.ids:      

            self.write({'state': 'approved'})
            self.current_approval = '3'
            self.DG_approver_sign = self.env.user.user_signature
            message = "Vous avez un paiement pour la validation"
            self.activity_schedule('purchase_order_approval.mail_activity_data_approval', user_id=company_id.po_fourth_approver_ids.id, note=message)
        else:
            raise ValidationError(_("Seul %s peut approver !"% company_id.po_DG_approver_ids.id ))

    def action_cashier_approval(self):
        company_id=self.env.company
        if self.env.user.id in company_id.po_fourth_approver_ids.ids:
            self.write({'state': 'posted'})
           
            if self.related_payment_id:
                related_payment = self.env['account.payment.register'].browse(self.related_payment_id)
                
                if related_payment.exists():
                    # Call a method on the related payment record
                    related_payment.action_create_payments()
                else:
                    _logger.error("Related payment record with ID %s does not exist", self.related_payment_id.id)
        else:
            raise ValidationError(_("Seul %s peut approver !"% company_id.po_fourth_approver_ids.id ))
        
    def action_reject(self):
        company_id=self.env.company
        current_approver = None
        if self.current_approval =='1':
            current_approver=company_id.po_third_approver_ids
        elif self.current_approval =='2':
            current_approver=company_id.po_DG_approver_ids
        else:
            raise UserError(_(f"{self.current_approval},{type(self.current_approval)}"))
        if self.env.user.id in current_approver.ids:
            self.write({'state': 'rejected'})
   
        else:
            raise ValidationError(_("Seul %s peut refuser cette DA !" % current_approver.name))

    def rollback(self):
        '''to cancel all the signature already done to false'''
        self.write({
            'DFC_approver_sign': False,
            'DG_approver_sign': False,
            'current_approval': False,
        })
        
        
        

class CustomPaymentRegister(models.TransientModel):
    _inherit = 'account.payment.register'
    payment_id = fields.Many2one('account.payment', string='Created Payment')

    
    def _collect_payment_vals(self):
    
        payment_vals = {
                'amount': self.amount,
                'partner_id': self.partner_id.id,
                'journal_id': self.journal_id.id,
                'payment_method_line_id': self.payment_method_line_id.id,
                'date': self.payment_date,
                'currency_id': self.currency_id.id,
                'ref': self.communication,
                'partner_bank_id': self.partner_bank_id.id,
                'bank_reference': self.bank_reference,
                'cheque_reference': self.cheque_reference,
        
            }
        return payment_vals


    def action_submit_for_approval(self):
        payment_vals = self._collect_payment_vals()
        payment = self.env['account.payment'].create(payment_vals)
        self.payment_id = payment.id
        payment.related_payment_id = self.id

        
        # raise ValidationError(_(f"{self.id}// {payment.related_payment_id}//{number}"))
        # Call the approval flow for each payment created
        payment.action_submit_for_approval()

I have tried several ways to link the both model throught the fields payment_id in account.register.payment model and related_payment_id in account.payment but it still giving the "self_id" in this _unknow(actual_id,)