PY3: use MutableMapping instead of DictMixin

scrapy/item.py

@@ -5,7 +5,8 @@ See documentation in docs/topics/item.rst
 """
 
 from pprint import pformat
-from UserDict import DictMixin
+from collections import MutableMapping
+from abc import ABCMeta
 import six
 
 from scrapy.utils.trackref import object_ref
@@ -20,7 +21,7 @@ class Field(dict):
     """Container of field metadata"""
 
 
-class ItemMeta(type):
+class ItemMeta(ABCMeta):
 
     def __new__(mcs, class_name, bases, attrs):
         fields = {}
@@ -37,7 +38,7 @@ class ItemMeta(type):
         return cls
 
 
-class DictItem(DictMixin, BaseItem):
+class DictItem(MutableMapping, BaseItem):
 
     fields = {}
 
@@ -71,6 +72,19 @@ class DictItem(DictMixin, BaseItem):
                 (name, value))
         super(DictItem, self).__setattr__(name, value)
 
+    def __len__(self):
+        return len(self._values)
+
+    def __iter__(self):
+        for i in getattr(self, "_values", ()):
+            yield i
+
+    def __hash__(self):
+        if hasattr(self, "_values"):
+            return hash(frozenset(self._values.items()))
+        else:
+            return 1
+
     def keys(self):
         return self._values.keys()
 
@@ -81,6 +95,5 @@ class DictItem(DictMixin, BaseItem):
         return self.__class__(self)
 
 
-class Item(DictItem):
-
-    __metaclass__ = ItemMeta
+class Item(six.with_metaclass(ItemMeta, DictItem)):
+    pass

scrapy/tests/test_item.py

@@ -1,6 +1,7 @@
 import unittest
 
 from scrapy.item import Item, Field
+import six
 
 
 class ItemTest(unittest.TestCase):
@@ -52,8 +53,13 @@ class ItemTest(unittest.TestCase):
         i['name'] = u'John Doe'
         i['number'] = 123
         itemrepr = repr(i)
-        self.assertEqual(itemrepr,
-                         "{'name': u'John Doe', 'number': 123}")
+
+        if six.PY2:
+            self.assertEqual(itemrepr,
+                             "{'name': u'John Doe', 'number': 123}")
+        else:
+            self.assertEqual(itemrepr,
+                             "{'name': 'John Doe', 'number': 123}")
 
         i2 = eval(itemrepr)
         self.assertEqual(i2['name'], 'John Doe')
@@ -106,13 +112,13 @@ class ItemTest(unittest.TestCase):
 
         i = TestItem()
         i['name'] = u'John'
-        self.assertEqual(i.keys(), ['name'])
-        self.assertEqual(i.values(), ['John'])
+        self.assertEqual(list(i.keys()), ['name'])
+        self.assertEqual(list(i.values()), ['John'])
 
         i['keys'] = u'Keys'
         i['values'] = u'Values'
-        self.assertSortedEqual(i.keys(), ['keys', 'values', 'name'])
-        self.assertSortedEqual(i.values(), [u'Keys', u'Values', u'John'])
+        self.assertSortedEqual(list(i.keys()), ['keys', 'values', 'name'])
+        self.assertSortedEqual(list(i.values()), [u'Keys', u'Values', u'John'])
 
     def test_metaclass_inheritance(self):
         class BaseItem(Item):
@@ -125,8 +131,8 @@ class ItemTest(unittest.TestCase):
 
         i = TestItem()
         i['keys'] = 3
-        self.assertEqual(i.keys(), ['keys'])
-        self.assertEqual(i.values(), [3])
+        self.assertEqual(list(i.keys()), ['keys'])
+        self.assertEqual(list(i.values()), [3])
 
     def test_to_dict(self):
         class TestItem(Item):