added MultiValuedField to newitem

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%40981

scrapy/trunk/scrapy/contrib_exp/newitem/fields.py

@@ -3,7 +3,7 @@ import decimal
 import re
 
 
-__all__ = ['BooleanField', 'DateField', 'DecimalField',
+__all__ = ['MultiValuedField', 'BooleanField', 'DateField', 'DecimalField',
            'FloatField', 'IntegerField', 'StringField']
 
 
@@ -34,6 +34,21 @@ class Field(object):
         return ' '.join(value)
 
 
+class MultiValuedField(Field):
+    def __init__(self, field_type, required=False, default=None):
+        self._field = field_type()
+        super(MultiValuedField, self).__init__(required, default)
+
+    def to_python(self, value):
+        if value is None:
+            return []
+        else:
+            return [self._field.to_python(v) for v in value]
+
+    def deiter(self, value):
+        return value
+
+
 class BooleanField(Field):
     def to_python(self, value):
         if value in (True, False): return value

scrapy/trunk/scrapy/tests/test_newitem.py

@@ -13,3 +13,12 @@ class NewItemTest(unittest.TestCase):
         i.name = 'name'
         assert i.name == 'name'
 
+    def test_multi(self):
+        class TestMultiItem(Item):
+            name = StringField()
+            names = MultiValuedField(StringField)
+
+        i = TestMultiItem()
+        i.name = 'name'
+        i.names = ['name1', 'name2']
+        assert i.names == ['name1', 'name2']