added Pipe parser

scrapy/contrib/loader/processor.py

@@ -29,6 +29,23 @@ class ApplyConcat(object):
         return list(values)
 
 
+class Pipe(object):
+
+    def __init__(self, *functions, **default_parser_context):
+        self.functions = functions
+        self.default_parser_context = default_parser_context
+    
+    def __call__(self, value, parser_context=None):
+        if parser_context:
+            context = MergeDict(parser_context, self.default_parser_context)
+        else:
+            context = self.default_parser_context
+        wrapped_funcs = [wrap_loader_context(f, context) for f in self.functions]
+        for func in wrapped_funcs:
+            value = func(value)
+        return value
+
+
 class TakeFirst(object):
 
     def __call__(self, values):

scrapy/tests/test_contrib_loader.py

@@ -1,7 +1,7 @@
 import unittest
 
 from scrapy.contrib.loader import ItemLoader, XPathItemLoader
-from scrapy.contrib.loader.processor import ApplyConcat, Join, Identity
+from scrapy.contrib.loader.processor import ApplyConcat, Join, Identity, Pipe
 from scrapy.newitem import Item, Field
 from scrapy.xpath import HtmlXPathSelector
 from scrapy.http import HtmlResponse
@@ -244,6 +244,16 @@ class ItemLoaderTest(unittest.TestCase):
         ip = TestItemLoader()
         self.assertRaises(KeyError, ip.add_value, 'wrong_field', [u'lala', u'lolo'])
 
+    def test_pipe_pprocwssor(self):
+        class TestItemLoader(NameItemLoader):
+            name_out = Pipe(lambda v: v[0], lambda v: v.title(), lambda v: v[:-1])
+
+        il = TestItemLoader()
+        il.add_value('name', [u'marta', u'other'])
+        self.assertEqual(il.get_output_value('name'), u'Mart')
+        item = il.populate_item()
+        self.assertEqual(item['name'], u'Mart')
+
 
 class TestXPathItemLoader(XPathItemLoader):
     default_item_class = TestItem