Scrapy：TypeError：__init__（）缺少1个必需的位置参数：'url'答案

【问题标题】：Scrapy: TypeError: __init__() missing 1 required positional argument: 'url'Scrapy：TypeError：__init__（）缺少1个必需的位置参数：'url'
【发布时间】：2019-07-05 18:39:03
【问题描述】：

我正在试用一个scrapy 包https://github.com/clemfromspace/scrapy-selenium。

我已经按照上面主要 github 页面上的说明进行操作。我开始了一个新的scrapy项目并创建了一个蜘蛛：

from scrapy_selenium import SeleniumRequest

from shutil import which

SELENIUM_DRIVER_NAME = 'firefox'
# SELENIUM_DRIVER_EXECUTABLE_PATH = which('chromedriver')
SELENIUM_DRIVER_EXECUTABLE_PATH = which('geckodriver')
SELENIUM_DRIVER_ARGUMENTS=['-headless']  # '--headless' if using chrome instead of firefox

USER_AGENT = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:48.0) Gecko/20100101 Firefox/48.0'


class MySpider(scrapy.Spider):

    start_urls = ["http://yahoo.com"]
    name = 'test'


    def start_requests(self):
        for url in self.start_urls:

            yield SeleniumRequest(url, self.parse_index_page)


    def parse_index_page(self, response):
        ....

输出：

 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.logstats.LogStats']
2019-07-05 14:14:44 [scrapy.middleware] WARNING: Disabled SeleniumMiddleware: SELENIUM_DRIVER_NAME and SELENIUM_DRIVER_EXECUTABLE_PATH must be set
2019-07-05 14:14:44 [scrapy.middleware] INFO: Enabled downloader middlewares:
['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
 'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
 ........
 'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware',
 'scrapy.downloadermiddlewares.stats.DownloaderStats']
2019-07-05 14:14:44 [scrapy.middleware] INFO: Enabled spider middlewares:
['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
 'scrapy.spidermiddlewares.referer.RefererMiddleware',
 'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
 'scrapy.spidermiddlewares.depth.DepthMiddleware']
2019-07-05 14:14:44 [scrapy.middleware] INFO: Enabled item pipelines:
[]
2019-07-05 14:14:44 [scrapy.core.engine] INFO: Spider opened
2019-07-05 14:14:44 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2019-07-05 14:14:44 [scrapy.extensions.telnet] INFO: Telnet console listening on 127.0.0.1:6023
2019-07-05 14:14:44 [scrapy.core.engine] ERROR: Error while obtaining start requests
Traceback (most recent call last):
  File "....\splashtest\lib\site-packages\scrapy\core\engine.py", line 127, in _next_request
    request = next(slot.start_requests)
  File "E:\ENVS\r3\scrapySelenium\scrapySelenium\spiders\test.py", line 55, in start_requests
    yield SeleniumRequest(url, self.parse_index_page)
  File "....\splashtest\lib\site-packages\scrapy_selenium\http.py", line 32, in __init__
    super().__init__(*args, **kwargs)
TypeError: __init__() missing 1 required positional argument: 'url'
2019-07-05 14:14:44 [scrapy.core.engine] INFO: Closing spider (finished)
2019-07-05 14:14:44 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'finish_reason': 'finished',
 'finish_time': datetime.datetime(2019, 7, 5, 18, 14, 44, 74274),
 'log_count/ERROR': 1,
 'log_count/INFO': 9,
 'log_count/WARNING': 1,
 'start_time': datetime.datetime(2019, 7, 5, 18, 14, 44, 66256)}
2019-07-05 14:14:44 [scrapy.core.engine] INFO: Spider closed (finished)

我做错了什么？

【问题讨论】：

标签： python selenium scrapy

【解决方案1】：

根据问题中的链接，scrapy_selenium.SeleniumRequest 构造函数采用初始参数 wait_time、wait_until、screenshot 和 script，并将所有剩余参数传递给 scrapy.Request 构造函数。

发布的代码用两个位置参数实例化了SeleniumRequest，这意味着不会将任何参数传递给Request 构造函数，从而导致出现问题。

要解决此问题，您可以按位置显式传递默认的 SeleniumRequest 参数：

yield SeleniumRequest(None, None, False, None, url, self.parse_index_page)

或通过关键字传递Request 参数（通常是一种更好的样式，因为它可以灵活应对默认参数的更改，并且更容易确定发生了什么）：

yield SeleniumRequest(url=url, callback=self.parse_index_page)

【讨论】：

感谢克雷格，我使用了第二个，它有效。仅供我自己参考，请查看： class SeleniumRequest(Request): """Scrapy Request subclass provides additional arguments""" def __init__(self, wait_time=None, wait_until=None, screenshot=False, script=None, *args, **kwargs)：“*args, **kwargs”是否基于基类——在这种情况下是scrapy的Request类？
@user61629 在SeleniumRequest 的构造函数的末尾，它会像这样调用Request 的构造函数：super().__init__(*args, **kwargs)（self 参数已经被super 绑定在python 3 中）。这就是将这些参数传递给基类的构造函数的原因。