diff --git a/models/sale_order.py b/models/sale_order.py
index 6913c8b..2e4bcba 100644
--- a/models/sale_order.py
+++ b/models/sale_order.py
@@ -12,11 +12,13 @@ from werkzeug import utils
 class SaleOrder(models.Model):
     _inherit = "sale.order"
     
+    donation_amount=fields.Integer()
     
 
     def _cart_update(self, product_id=None, line_id=None, add_qty=0, set_qty=0,donation_amount=0, **kwargs):
         """ Add or set product quantity, add_qty can be negative """
         self.ensure_one()
+        if donation_amount>0: self.donation_amount=donation_amount
         product_context = dict(self.env.context)
         product_context.setdefault('lang', self.sudo().partner_id.lang)
         SaleOrderLineSudo = self.env['sale.order.line'].sudo().with_context(product_context)
@@ -94,10 +96,11 @@ class SaleOrder(models.Model):
                     'custom_value': custom_value['custom_value']
                 }) for custom_value in custom_values]
 
-            if donation_amount>0:
+            if self.donation_amount:
+            
                 values['product_uom_qty']=1
-                values['price_unit']=int(donation_amount)
-                values['price_total']=int(donation_amount)
+                values['price_unit']=self.donation_amount
+                values['price_total']=self.donation_amount
 
             # create the line
             order_line = SaleOrderLineSudo.create(values)
@@ -144,10 +147,11 @@ class SaleOrder(models.Model):
                     order_line.tax_id,
                     self.company_id
                 )
-            if donation_amount>0:
+            if self.donation_amount:
+            
                 values['product_uom_qty']=1
-                values['price_unit']=int(donation_amount)
-                values['price_total']=int(donation_amount)
+                values['price_unit']=self.donation_amount
+                values['price_total']=self.donation_amount
             order_line.write(values)
 
             # link a product to the sales order