fixed PickeItemExporter bug, added unittest, and added pickle to suported feed exports formats

docs/topics/feed-exports.rst

@@ -64,6 +64,14 @@ XML
  * :setting:`FEED_FORMAT`: ``xml``
  * Exporter used: :class:`~scrapy.contrib.exporter.XmlItemExporter`
 
+.. _topics-feed-format-pickle:
+
+Pickle
+------
+
+ * :setting:`FEED_FORMAT`: ``pickle``
+ * Exporter used: :class:`~scrapy.contrib.exporter.PickleItemExporter`
+
 .. _topics-feed-format-marshal:
 
 Marshal

scrapy/contrib/exporter/__init__.py

@@ -5,7 +5,7 @@ Item Exporters are used to export/serialize items into different formats.
 import csv
 import pprint
 import marshal
-from cPickle import Pickler
+import cPickle as pickle
 from xml.sax.saxutils import XMLGenerator
 
 from scrapy.utils.py26 import json
@@ -178,12 +178,14 @@ class CsvItemExporter(BaseItemExporter):
 
 class PickleItemExporter(BaseItemExporter):
 
-    def __init__(self, file, protocol=0, **kwargs):
+    def __init__(self, file, protocol=2, **kwargs):
         self._configure(kwargs)
-        self.pickler = Pickler(file, protocol)
+        self.file =file
+        self.protocol = protocol
 
     def export_item(self, item):
-        self.pickler.dump(dict(self._get_serialized_fields(item)))
+        d = dict(self._get_serialized_fields(item))
+        pickle.dump(d, self.file, self.protocol)
 
 
 class MarshalItemExporter(BaseItemExporter):

scrapy/settings/default_settings.py

@@ -164,6 +164,7 @@ FEED_EXPORTERS_BASE = {
     'csv': 'scrapy.contrib.exporter.CsvItemExporter',
     'xml': 'scrapy.contrib.exporter.XmlItemExporter',
     'marshal': 'scrapy.contrib.exporter.MarshalItemExporter',
+    'pickle': 'scrapy.contrib.exporter.PickleItemExporter',
 }
 
 HTTPCACHE_ENABLED = False

scrapy/tests/test_contrib_exporter.py

@@ -88,6 +88,19 @@ class PickleItemExporterTest(BaseItemExporterTest):
     def _check_output(self):
         self._assert_expected_item(pickle.loads(self.output.getvalue()))
 
+    def test_export_multiple_items(self):
+        i1 = TestItem(name='hello', age='world')
+        i2 = TestItem(name='bye', age='world')
+        f = StringIO()
+        ie = PickleItemExporter(f)
+        ie.start_exporting()
+        ie.export_item(i1)
+        ie.export_item(i2)
+        ie.finish_exporting()
+        f.reset()
+        self.assertEqual(pickle.load(f), i1)
+        self.assertEqual(pickle.load(f), i2)
+
 
 class CsvItemExporterTest(BaseItemExporterTest):