I want to give a condition on opportunity won stage.

First, I created an opportunity, then I will create a quotation against that opportunity. 

When the opportunity becomes won. I will convert the opportunity to the won stage. In that won button, I needed to inherit. 

When I click on the opportunity won button, it will automatically convert its corresponding quotation to the Done stage.

How can implement this?

Below is my code:

class Opportunity(models.Model):
      _inherit = "crm.lead"
      
      @api.multi
      def action_set_won(self, context=None):
        
          
          
          return {
              'name': _('Project Confirmations'),
              'type': 'ir.actions.act_window',
              'view_type': 'form',
              'view_mode': 'form',
              'res_model': 'crm.won',
              'target': 'new',
              'context': {'opportunity_id': self.id}
              
        }

In my wizard.py

from openerp import models, fields, api


class crm_won(models.TransientModel):
      _name = 'crm.won'

      def _get_all_quotations(self):
          return self.env['sale.order'].browse(self.env.context.get('opportunity_id'))

      quotation_ids = fields.Many2one('sale.order', string='Quotations', default=_get_all_quotations)

      update_quotation = fields.Selection([('yes', 'YES'), ('no', 'NO')], string='Update Quotation Stage')
      opportunity_id = fields.Many2one('crm.lead',string='opportunity')
      

      @api.multi
      def update_opportunity(self):
          for record in self:
              if self.env['crm.lead'].search([('opportunity_id','=',self.opportunity_id)]): 
                 quotation_ids               
              if record.update_quotation == "YES":
                 for quotation in quotation_ids:
                     quotation.state = "Done"

But some missing in my code. I don't know, what is the issue. Can anyone please help me?

def _get_all_quotations(self): 

this function is not working properply. Anything is missing in this funtion?