[IMP] purchase: when product qty is change in confirmed PO display log note

addons/purchase/__manifest__.py

@@ -21,6 +21,7 @@
         'views/stock_views.xml',
         'views/res_config_settings_views.xml',
         'views/res_partner_views.xml',
+        'views/purchase_template.xml',
         'report/purchase_report_views.xml',
         'data/mail_template_data.xml',
         'views/portal_templates.xml',

addons/purchase/models/purchase.py

@@ -580,6 +580,12 @@ class PurchaseOrderLine(models.Model):
 
     @api.multi
     def write(self, values):
+        if 'product_qty' in values:
+            for line in self:
+                if line.order_id.state == 'purchase':
+                    line.order_id.message_post_with_view('purchase.track_po_line_template',
+                                                         values={'line': line, 'product_qty': values['product_qty']},
+                                                         subtype_id=self.env.ref('mail.mt_note').id)
         result = super(PurchaseOrderLine, self).write(values)
         # Update expected date of corresponding moves
         if 'date_planned' in values:

addons/purchase/views/purchase_template.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<odoo>
+
+    <template id="track_po_line_template">
+        <div>
+            <strong>The ordered quantity has been updated.</strong>
+            <ul>
+                <li><t t-esc="line.order_id.product_id.display_name"/>:</li>
+                Ordered Quantity: <t t-esc="line.product_qty" /> -&gt; <t t-esc="float(product_qty)"/><br/>
+                <t t-if='line.order_id.product_id.type in ("consu", "product")'>
+                    Received Quantity: <t t-esc="line.qty_received" /><br/>
+                </t>
+                Billed Quantity: <t t-esc="line.qty_invoiced"/>
+            </ul>
+        </div>
+    </template>
+</odoo>