defaults.py 文件源码

def page_not_found(request, exception, template_name='404.html'):
    """
    Default 404 handler.

    Templates: :template:`404.html`
    Context:
        request_path
            The path of the requested URL (e.g., '/app/pages/bad_page/')
        exception
            The message from the exception which triggered the 404 (if one was
            supplied), or the exception class name
    """
    exception_repr = exception.__class__.__name__
    # Try to get an "interesting" exception message, if any (and not the ugly
    # Resolver404 dictionary)
    try:
        message = exception.args[0]
    except (AttributeError, IndexError):
        pass
    else:
        if isinstance(message, six.text_type):
            exception_repr = message
    context = {
        'request_path': request.path,
        'exception': exception_repr,
    }
    try:
        template = loader.get_template(template_name)
        body = template.render(context, request)
        content_type = None             # Django will use DEFAULT_CONTENT_TYPE
    except TemplateDoesNotExist:
        template = Engine().from_string(
            '<h1>Not Found</h1>'
            '<p>The requested URL {{ request_path }} was not found on this server.</p>')
        body = template.render(Context(context))
        content_type = 'text/html'
    return http.HttpResponseNotFound(body, content_type=content_type)