ad field stock quantity in line purchase

__init__.py

@@ -9,4 +9,5 @@ def register():
     Pool.register(
         purchase.Configuration,
         purchase.Purchase,
+        purchase.Line,
         module='purchase_co', type_='model')

purchase.py

@@ -1,10 +1,11 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
 from datetime import date, timedelta
-
+from trytond.pyson import Eval
 from trytond.pool import PoolMeta, Pool
 from trytond.model import fields
 from trytond.exceptions import UserError
+from trytond.transaction import Transaction
 
 
 class Configuration(metaclass=PoolMeta):
@@ -57,3 +58,33 @@ class Purchase(metaclass=PoolMeta):
             ], fields_names=['reference'])
             if len(duplicates) >= 2:
                 raise UserError('Al parecer esta compra esta duplicada!')
+
+
+class Line(metaclass=PoolMeta):
+    __name__ = 'purchase.line'
+
+    stock_quantity = fields.Function(fields.Float('Stock Quantity',
+        digits=(16, Eval('default_uom_digits', 2))),
+        'on_change_with_stock_quantity')
+
+    @fields.depends('product')
+    def on_change_with_stock_quantity(self, name=None):
+        if self.product:
+            context = {'stock_date_end': self.purchase.purchase_date}
+            Location = Pool().get('stock.location')
+            locations = Location.search([
+                ('type', '=', 'warehouse')
+            ])
+            location_ids = [l.storage_location.id for l in locations if l.storage_location]
+            product_ids = [self.product.id]
+            quantity = 0
+            with Transaction().set_context(context):
+                Product = Pool().get('product.product')
+                pbl = Product.products_by_location(
+                    location_ids,
+                    grouping=('product', ),
+                    grouping_filter=(product_ids,))
+                for v in pbl.values():
+                    quantity += v
+                quantity = quantity
+            return quantity

purchase.xml

@@ -9,5 +9,10 @@ this repository contains the full copyright notices and license terms. -->
           <field name="inherit" ref="purchase.purchase_configuration_view_form"/>
           <field name="name">configuration_form</field>
       </record>
+      <record model="ir.ui.view" id="purchase_line_view_form">
+          <field name="model">purchase.line</field>
+          <field name="inherit" ref="purchase.purchase_line_view_form"/>
+          <field name="name">purchase_line_form</field>
+      </record>
     </data>
 </tryton>

view/purchase_line_form.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
+this repository contains the full copyright notices and license terms. -->
+<data>
+    <xpath expr="/form/notebook/page[@id='general']/group[@id='delivery_date']" position="after">
+        <label name="stock_quantity"/>
+        <field name="stock_quantity"/>
+    </xpath>
+</data>