动态 start_urls 值

Question

我是scrapy和python的新手。我已经编写了一个可以在初始化的 start_urls 值下正常工作的蜘蛛。

如果我在 Init 中的代码中添加一个文字，它也可以正常工作

{ self.start_urls = 'http://something.com' }

但是，当我从一个 json 文件中读取值并创建一个列表时，我得到了关于缺少 %20 的相同错误

我觉得我在 scrapy 或 python 中遗漏了一些明显的东西，因为我是一个 nube。

class SiteFeedConstructor(CrawlSpider, FeedConstructor):

    name = "Data_Feed"
    start_urls = ['http://www.cnn.com/']

    def __init__(self, *args, **kwargs):

    FeedConstructor.__init__(self, **kwargs)
    kwargs = {}
    super(SiteFeedConstructor, self).__init__(*args, **kwargs)

    self.name = str(self.config_json.get('name', 'Missing value'))
    self.start_urls = str(self.config_json.get('start_urls', 'Missing value'))
    self.start_urls = self.start_urls.split(",")

错误：

Traceback (most recent call last):
  File "/usr/bin/scrapy", line 4, in <module>
    execute()
  File "/usr/lib/python2.7/dist-packages/scrapy/cmdline.py", line 132, in execute
    _run_print_help(parser, _run_command, cmd, args, opts)
  File "/usr/lib/python2.7/dist-packages/scrapy/cmdline.py", line 97, in _run_print_help
    func(*a, **kw)
  File "/usr/lib/python2.7/dist-packages/scrapy/cmdline.py", line 139, in _run_command
    cmd.run(args, opts)
  File "/usr/lib/python2.7/dist-packages/scrapy/commands/runspider.py", line 64, in run
    self.crawler.crawl(spider)
  File "/usr/lib/python2.7/dist-packages/scrapy/crawler.py", line 42, in crawl
    requests = spider.start_requests()
  File "/usr/lib/python2.7/dist-packages/scrapy/spider.py", line 55, in start_requests
    reqs.extend(arg_to_iter(self.make_requests_from_url(url)))
  File "/usr/lib/python2.7/dist-packages/scrapy/spider.py", line 59, in make_requests_from_url
    return Request(url, dont_filter=True)
  File "/usr/lib/python2.7/dist-packages/scrapy/http/request/__init__.py", line 26, in __init__
    self._set_url(url)
  File "/usr/lib/python2.7/dist-packages/scrapy/http/request/__init__.py", line 61, in _set_url
    raise ValueError('Missing scheme in request url: %s' % self._url)
ValueError: Missing scheme in request url: Missing%20value

Answer 1

而不是定义__init__() 覆盖start_requests() 方法：

这是 Scrapy 在打开爬虫时调用的方法 在未指定特定 URL 时进行抓取。如果特定的 URL 指定，则使用 make_requests_from_url() 来创建 要求。这个方法也只从 Scrapy 调用一次，所以它是 安全地将其实现为生成器。

class SiteFeedConstructor(CrawlSpider, FeedConstructor):
    name = "Data_Feed"

    def start_requests(self):
        self.name = str(self.config_json.get('name', 'Missing value'))
        for url in str(self.config_json.get('start_urls', 'Missing value')).split(","):
            yield self.make_requests_from_url(url)