Pylons mako 模板：调试“内部服务器错误” /“无类型”错误

Question

我经常在使用 Pylons 0.9.7 的 Mako 模板中遇到此错误：

AttributeError: 'NoneType' object has no attribute 'decode'

通常我输入了一个不存在的变量名称，尝试使用代码行中的 linbebreak 或其他一些小错误。绝对是我的错。

这会导致浏览器中出现“内部服务器错误”，调试视图中也会出现同样的情况，以及堆栈跟踪从 HTTPServer 开始并以 mako/exceptions.py 中的 AttributeError 结束。

我可以做些什么来使其更容易调试，例如找出 Mako 模板中生成异常的行？谢谢！

Answer 1

我不太确定这是同一个问题，但据我记得，当您使用 AJAX 加载页面片段时，这种情况经常发生。那么你就不会得到比这条消息更有用的信息了。

但是，如果您尝试在浏览器中加载 AJAX 请求本身的地址（如果需要，将 post 参数替换为 get 参数），您将得到一个“正常”调试页面。

Answer 2

就我而言，事实证明我的模板中存在除以 0 的错误。这会产生内部服务器错误，并在控制台输出中产生非常无用的堆栈跟踪。

我知道，听起来我无论如何都不应该在模板中使用这种逻辑，但在这种情况下，我认为这样做是有意义的。这是我除以 0 后得到的堆栈跟踪：

Exception happened during processing of request from ('127.0.0.1', 50681)
Traceback (most recent call last):
  File "/Library/Python/2.6/site-packages/Paste-1.7.4-py2.6.egg/paste/httpserver.py", line 1068, in process_request_in_thread
    self.finish_request(request, client_address)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/SocketServer.py", line 320, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/SocketServer.py", line 615, in __init__
    self.handle()
  File "/Library/Python/2.6/site-packages/Paste-1.7.4-py2.6.egg/paste/httpserver.py", line 442, in handle
    BaseHTTPRequestHandler.handle(self)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/BaseHTTPServer.py", line 329, in handle
    self.handle_one_request()
  File "/Library/Python/2.6/site-packages/Paste-1.7.4-py2.6.egg/paste/httpserver.py", line 437, in handle_one_request
    self.wsgi_execute()
  File "/Library/Python/2.6/site-packages/Paste-1.7.4-py2.6.egg/paste/httpserver.py", line 287, in wsgi_execute
    self.wsgi_start_response)
  File "/Library/Python/2.6/site-packages/Paste-1.7.4-py2.6.egg/paste/cascade.py", line 130, in __call__
    return self.apps[-1](environ, start_response)
  File "/Library/Python/2.6/site-packages/Paste-1.7.4-py2.6.egg/paste/registry.py", line 375, in __call__
    app_iter = self.application(environ, start_response)
  File "/Library/Python/2.6/site-packages/Pylons-0.9.7-py2.6.egg/pylons/middleware.py", line 201, in __call__
    self.app, environ, catch_exc_info=True)
  File "/Library/Python/2.6/site-packages/Pylons-0.9.7-py2.6.egg/pylons/util.py", line 94, in call_wsgi_application
    app_iter = application(environ, start_response)
  File "/Library/Python/2.6/site-packages/WebError-0.10.2-py2.6.egg/weberror/evalexception.py", line 235, in __call__
    return self.respond(environ, start_response)
  File "/Library/Python/2.6/site-packages/WebError-0.10.2-py2.6.egg/weberror/evalexception.py", line 483, in respond
    return debug_info.content()
  File "/Library/Python/2.6/site-packages/WebError-0.10.2-py2.6.egg/weberror/evalexception.py", line 545, in content
    result = tmpl_formatter(self.exc_value)
  File "/Library/Python/2.6/site-packages/Pylons-0.9.7-py2.6.egg/pylons/error.py", line 43, in mako_html_data
    css=False)
  File "/Library/Python/2.6/site-packages/Mako-0.3.2-py2.6.egg/mako/template.py", line 189, in render
    return runtime._render(self, self.callable_, args, data)
  File "/Library/Python/2.6/site-packages/Mako-0.3.2-py2.6.egg/mako/runtime.py", line 403, in _render
    _render_context(template, callable_, context, *args, **_kwargs_for_callable(callable_, data))
  File "/Library/Python/2.6/site-packages/Mako-0.3.2-py2.6.egg/mako/runtime.py", line 434, in _render_context
    _exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
  File "/Library/Python/2.6/site-packages/Mako-0.3.2-py2.6.egg/mako/runtime.py", line 457, in _exec_template
    callable_(context, *args, **kwargs)
  File "memory:0x1040470d0", line 54, in render_body
  File "/Library/Python/2.6/site-packages/Mako-0.3.2-py2.6.egg/mako/exceptions.py", line 88, in __init__
    self.records = self._init(traceback)
  File "/Library/Python/2.6/site-packages/Mako-0.3.2-py2.6.egg/mako/exceptions.py", line 166, in _init
    line = line.decode('ascii', 'replace')
AttributeError: 'NoneType' object has no attribute 'decode'
----------------------------------------