Use Null constant from python-sql for comparisons

issue4143
review13701003

product.py

@@ -1,7 +1,8 @@
 #This file is part of Tryton.  The COPYRIGHT file at the top level of
 #this repository contains the full copyright notices and license terms.
 import datetime
-from sql import Literal
+
+from sql import Literal, Null
 from sql.aggregate import Count
 
 from trytond.model import ModelView, ModelSQL, MatchMixin, fields
@@ -212,7 +213,7 @@ class ProductSupplier(ModelSQL, ModelView, MatchMixin):
     @staticmethod
     def order_sequence(tables):
         table, _ = tables[None]
-        return [table.sequence == None, table.sequence]
+        return [table.sequence == Null, table.sequence]
 
     @staticmethod
     def default_company():
@@ -316,7 +317,7 @@ class ProductSupplierPrice(ModelSQL, ModelView, MatchMixin):
     @staticmethod
     def order_sequence(tables):
         table, _ = tables[None]
-        return [table.sequence == None, table.sequence]
+        return [table.sequence == Null, table.sequence]
 
     @staticmethod
     def default_quantity():

purchase.py

@@ -3,7 +3,8 @@
 import datetime
 from itertools import chain
 from decimal import Decimal
-from sql import Table, Literal
+
+from sql import Table, Literal, Null
 from sql.functions import Overlay, Position
 from sql.aggregate import Count
 from sql.operators import Concat
@@ -288,8 +289,8 @@ class Purchase(Workflow, ModelSQL, ModelView):
                                 purchase_line.id))
                         ).select(sql_table.id,
                             where=((sql_table.state == 'confirmed')
-                                & ((invoice_line.id != None)
-                                    | (move.id != None))))
+                                & ((invoice_line.id != Null)
+                                    | (move.id != Null))))
             cursor.execute(*sql_table.update(
                     columns=[sql_table.state],
                     values=['processing'],
@@ -1011,7 +1012,7 @@ class PurchaseLine(ModelSQL, ModelView):
     @staticmethod
     def order_sequence(tables):
         table, _ = tables[None]
-        return [table.sequence == None, table.sequence]
+        return [table.sequence == Null, table.sequence]
 
     @staticmethod
     def default_type():

setup.py

@@ -41,7 +41,7 @@ if minor_version % 2:
         'hg+http://hg.tryton.org/modules/%s#egg=%s-%s' % (
             name[8:], name, version))
 
-requires = ['python-sql']
+requires = ['python-sql >= 0.4']
 for dep in info.get('depends', []):
     if not re.match(r'(ir|res|webdav)(\W|$)', dep):
         requires.append(get_require_version('trytond_%s' % dep))

stock.py

@@ -1,6 +1,8 @@
 #This file is part of Tryton.  The COPYRIGHT file at the top level of
 #this repository contains the full copyright notices and license terms.
 import datetime
+
+from sql import Null
 from sql.operators import Concat
 
 from trytond.model import Workflow, ModelView, fields
@@ -190,7 +192,7 @@ class Move:
             cursor.execute(*sql_table.update(
                     columns=[sql_table.origin],
                     values=[Concat('purchase.line,', sql_table.purchase_line)],
-                    where=sql_table.purchase_line != None))
+                    where=sql_table.purchase_line != Null))
             table.drop_column('purchase_line')
 
     @classmethod