如何在scrapy downloader中间件中获取响应体

如果页面上没有找到某些XPath,我需要能够重试请求。所以我写了这个中间件:

class ManualRetryMiddleware(RetryMiddleware):
    def process_response(self, request, response, spider):
        if not spider.retry_if_not_found:
            return response
        if not hasattr(response, 'text') and response.status != 200:
            return super(ManualRetryMiddleware, self).process_response(request, response, spider)
        found = False
        for xpath in spider.retry_if_not_found:
            if response.xpath(xpath).extract():
                found = True
                break
        if not found:
            return self._retry(request, "Didn't find anything useful", spider)
        return response

并在 settings.py :

DOWNLOADER_MIDDLEWARES = {
    'myproject.middlewares.ManualRetryMiddleware': 650,
    'scrapy.downloadermiddlewares.retry.RetryMiddleware': None,
}

当我运行蜘蛛时,我得到

AttributeError: 'Response' object has no attribute 'xpath'

text 财产和 response.body

那么,我如何在中间件中检查页面内容呢?有些页面可能不包含我需要的详细信息,因此我希望能够稍后再试。