类型错误：需要字符串或缓冲区，用户未找到

Question

我需要爬取last.fm上的用户信息（这是一个大学作业）。我刚学Python，遇到了以下错误：

 Traceback (most recent call last):
  File "crawler.py", line 23, in <module>
    for f in user_.get_friends(limit='200'):
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/pylast.py", line 2717, in get_friends
    for node in _collect_nodes(limit, self, "user.getFriends", False):
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/pylast.py", line 3409, in _collect_nodes
    doc = sender._request(method_name, cacheable, params)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/pylast.py", line 969, in _request
    return _Request(self.network, method_name, params).execute(cacheable)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/pylast.py", line 721, in __init__
    self.sign_it()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/pylast.py", line 727, in sign_it
    self.params['api_sig'] = self._get_signature()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/pylast.py", line 740, in _get_signature
    string += self.params[name]
TypeError: coercing to Unicode: need string or buffer, User found

我使用pylast库来进行爬取。我想做的是：

我想获取一个用户的朋友，以及这些朋友的朋友。当我在一个循环里面再放一个循环时，就出现了错误。以下是我的代码：

network = pylast.get_lastfm_network(api_key = API_KEY, api_secret = API_SECRET, username = username, password_hash = password_hash)
user = network.get_user("vidarnelson")

friends = user.get_friends(limit='200')

i = 1

for friend in friends:
 user_ = network.get_user(friend)
 print '#%d %s' % (i, friend)
 i = i + 1

 for f in user_.get_friends(limit='200'):
  print f

有什么建议吗？

提前谢谢你们。祝好！

Answer 1

看起来 get_friends 这个函数会返回一个用户对象的列表，所以你不需要对它里面的每个用户再调用 get_user。你只需要直接使用：

for friend in friends:
    for f in friend.get_friends(limit='200'):
        ...