Scrapy没有通过元属性传递正确的项目

Question

我有类似的问题，下面的个人有。我试图使用元属性传递一个项目。我看到输出的项目数量正确，但它们是单个项目的重复项目。有人可以帮忙吗？我在对前一个人的帖子的回复中猜测，这应该是一个明显的解决办法。

https://github.com/scrapy/scrapy/issues/1257

def parse(self, response): 
# some treatment 
# a loop 
    request = scrapy.Request(url=<calculated_url>, callback=parseChapter) 
    request.meta['item'] = # a dictionary containing some data of the just parsed page 
    yield request 

def parseChapter(self, response): 
# some treatment 
# a loop 
    request = scrapy.Request(url=<calculated_url>, callback=parseCategory) 
    request.meta['item'] = # a dictionary containing some data of the just parsed page 
    # print request.meta['item'] is good and different in every iteration 
    yield request 

def parseCategory(self, response): 
# print response.meta['item'] is not good because it displays the same value many times 
# for every new call of parseChapter, meta['item'] received is always the same 
# some treatment 

Answer 1

最有可能的，你修改了该项目的每个迭代的for循环，而不是创建一个新的。

因此，所有请求都以相同的值发送。即项目变量的最后值。

def parseChapter(self, response): 
# some treatment 
# a loop 
    request = scrapy.Request(url=<calculated_url>, callback=parseCategory) 
    request.meta['item'] = my_item_dict.copy() 
    # print request.meta['item'] is good and different in every iteration 
    yield request