python exceptions.UnicodeDecodeError：’ascii’编解码器无法解码字节0xa7

def process_item(self,item,spider):
        import pdb; pdb.set_trace()
        ID = str(uuid.uuid5(uuid.NAMESPACE_DNS,item['link']))

我收到了这个错误：

Traceback (most recent call last):
          File "C:\Python27\lib\site-packages\scrapy-0.20.2-py2.7.egg\scrapy\mid
dleware.py",line 62,in _process_chain
            return process_chain(self.methods[methodname],obj,*args)
          File "C:\Python27\lib\site-packages\scrapy-0.20.2-py2.7.egg\scrapy\uti
ls\defer.py",line 65,in process_chain
            d.callback(input)
          File "C:\Python27\lib\site-packages\twisted\internet\defer.py",line 3
82,in callback
            self._startruncallbacks(result)
          File "C:\Python27\lib\site-packages\twisted\internet\defer.py",line 4
90,in _startruncallbacks
            self._runcallbacks()
        --- <exception caught here> ---
          File "C:\Python27\lib\site-packages\twisted\internet\defer.py",line 5
77,in _runcallbacks
            current.result = callback(current.result,*args,**kw)
          File "General_Spider_code_version_2\pipelines.py",line 7,in process_
item
            ID = str(uuid.uuid5(uuid.NAMESPACE_DNS,item['link']))
          File "C:\Python27\lib\uuid.py",line 549,in uuid5
            hash = sha1(namespace.bytes + name).digest()
        exceptions.UnicodeDecodeError: 'ascii' codec can't decode byte 0xa7 in p
osition 1: ordinal not in range(128)

我试图调试项目[‘link’]

这就是结果

-> ID = str(uuid.uuid5(uuid.NAMESPACE_DNS,item['link']))
(Pdb) item['link']
u'http://dubai.dubizzle.com/property-for-rent/residential/apartmentflat/2014/4/6
/palm-jumeirah-abu-keibal-3-br-maid-partial-2/?back=ZHViYWkuZHViaXp6bGUuY29tL3By
b3BlcnR5LWZvci1yZW50L3Jlc2lkZW50aWFsL2FwYXJ0bWVudGZsYXQv&pos=1'
(Pdb)

如你所见,项目[‘link’]是unicode

EDIT1

当我将项目[‘link’]更改为任何其他属性(如item [‘date’]时,代码完美无缺