Python 尝试连接到MongoDB TypeError时出错：uu init_uu（）缺少2个必需的位置参数：'；蒙哥乌里'；和'；mongo#u db'；

这是使用Scrapy CLI；我目前在安装了mongodb和pymongo的Ubuntu18服务器上运行scrapy，但每当我尝试运行我的爬行器“scrapy crawl event_spider”时，我都会遇到以下运行时错误：TypeError:init（）缺少2个必需的位置参数：“mongo_uri”和“mongo_db”

在my settings.py文件中，我定义了：

ITEM_PIPELINES = {
    'astro_events.pipelines.MongoDBPipeline': 300,
}

MONGODB_SERVER = "localhost"
MONGODB_PORT = 27017
MONGODB_DB = "astro_events"
MONGODB_COLLECTION = "events" 

在我的piplines.py中，我有：

import pymongo
from scrapy.exceptions import DropItem
import logging

from itemadapter import ItemAdapter

class MongoDBPipeline(object):

    collection_name = 'events'

    def __init__(self, mongo_uri, mongo_db):
        self.mongo_uri = mongo_uri
        self.mongo_db = mongo_db

        @classmethod
        def from_crawler(cls, crawler):
            ## pull in information from settings.py
            return cls(
                mongo_uri=crawler.settings.get('MONGODB_SERVER'),
                mongo_db=crawler.settings.get('MONGODB_DB')
            )

    def open_spider(self, spider):
        ## initializing spider
        ## opening db connection
        self.client = pymongo.MongoClient(self.mongo_uri)
        self.db = self.client[self.mongo_db]

    def close_spider(self, spider):
        ## clean up when spider is closed
        self.client.close()

    def process_item(self, item, spider):
        ## how to handle each post
        self.db[self.collection_name].insert(dict(item))
        logging.debug("Post added to MongoDB!")
        return item

我想知道的是，我得到这个错误是因为MongoDB在我的服务器上没有正确设置，还是我的设置或管道文件中有错误。我已经验证了MongoDB是否在端口27017的127.0.0.1（本地主机）上运行。我只是有点不知所措，不知何去何从。如果我需要发布更多信息，请告诉我。在实现数据库部分之前，我测试了我的spider，它工作得很好，所以我想我可以排除这种可能性

编辑： 以下是其抛出的确切错误：

Unhandled error in Deferred:
2020-11-09 23:34:19 [twisted] CRITICAL: Unhandled error in Deferred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/scrapy/crawler.py", line 192, in crawl
    return self._crawl(crawler, *args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/scrapy/crawler.py", line 196, in _crawl
    d = crawler.crawl(*args, **kwargs)
  File "/home/jcmq6b/.local/lib/python3.6/site-packages/twisted/internet/defer.py", line 1613, in unwindGenerator
    return _cancellableInlineCallbacks(gen)
  File "/home/jcmq6b/.local/lib/python3.6/site-packages/twisted/internet/defer.py", line 1529, in _cancellableInlineCallbacks
    _inlineCallbacks(None, g, status)
--- <exception caught here> ---
  File "/home/jcmq6b/.local/lib/python3.6/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
  File "/usr/local/lib/python3.6/dist-packages/scrapy/crawler.py", line 87, in crawl
    self.engine = self._create_engine()
  File "/usr/local/lib/python3.6/dist-packages/scrapy/crawler.py", line 101, in _create_engine
    return ExecutionEngine(self, lambda _: self.stop())
  File "/usr/local/lib/python3.6/dist-packages/scrapy/core/engine.py", line 70, in __init__
    self.scraper = Scraper(crawler)
  File "/usr/local/lib/python3.6/dist-packages/scrapy/core/scraper.py", line 71, in __init__
    self.itemproc = itemproc_cls.from_crawler(crawler)
  File "/usr/local/lib/python3.6/dist-packages/scrapy/middleware.py", line 53, in from_crawler
    return cls.from_settings(crawler.settings, crawler)
  File "/usr/local/lib/python3.6/dist-packages/scrapy/middleware.py", line 35, in from_settings
    mw = create_instance(mwcls, settings, crawler)
  File "/usr/local/lib/python3.6/dist-packages/scrapy/utils/misc.py", line 173, in create_instance
    instance = objcls(*args, **kwargs)
builtins.TypeError: __init__() missing 2 required positional arguments: 'mongo_uri' and 'mongo_db'

---

只是因为其他人偶然发现了同样的问题

记住，当涉及到Python识别时很重要：

import pymongo
from scrapy.exceptions import DropItem
import logging

from itemadapter import ItemAdapter

class MongoDBPipeline(object):

    collection_name = 'events'

    def __init__(self, mongo_uri, mongo_db):
        self.mongo_uri = mongo_uri
        self.mongo_db = mongo_db
    
'''
The problem was the following decorator and method declare 
inside the __init__ method (due to the wrong indentation in the orginal code)
That makes it a closure instead of a class method. 
And the decorator didn't run at all. Hence the error. 
'''
    @classmethod
    def from_crawler(cls, crawler):
      return cls(
        mongo_uri=crawler.settings.get('MONGODB_SERVER'),
        mongo_db=crawler.settings.get('MONGODB_DB')
      )

    def open_spider(self, spider):
        ## initializing spider
        ## opening db connection
        self.client = pymongo.MongoClient(self.mongo_uri)
        self.db = self.client[self.mongo_db]

    def close_spider(self, spider):
        ## clean up when spider is closed
        self.client.close()

    def process_item(self, item, spider):
        ## how to handle each post
        self.db[self.collection_name].insert(dict(item))
        logging.debug("Post added to MongoDB!")
        return item

---

你是如何初始化你的对象的？这听起来可能很傻，但您是否传递了所需的两个参数？我是新手，所以可能弄错了，但我认为当创建MongoDB管道时，它会使用从@classmethod from_crawler检索到的信息进行初始化，该信息应该进入设置以获取我声明的MongoDB设置。我试着跟随这个例子，你的缩进显示你在你的init中声明了

from_crawler

方法，这就是你实际文件中的内容吗？是的，它在我的init中，我刚刚回签了它，它现在工作了……哇，这是一个简单的修复。非常感谢。我知道我怎么没看到，你能接受我的回答吗，谢谢。

import pymongo
from scrapy.exceptions import DropItem
import logging

from itemadapter import ItemAdapter

class MongoDBPipeline(object):

    collection_name = 'events'

    def __init__(self, mongo_uri, mongo_db):
        self.mongo_uri = mongo_uri
        self.mongo_db = mongo_db
    
'''
The problem was the following decorator and method declare 
inside the __init__ method (due to the wrong indentation in the orginal code)
That makes it a closure instead of a class method. 
And the decorator didn't run at all. Hence the error. 
'''
    @classmethod
    def from_crawler(cls, crawler):
      return cls(
        mongo_uri=crawler.settings.get('MONGODB_SERVER'),
        mongo_db=crawler.settings.get('MONGODB_DB')
      )

    def open_spider(self, spider):
        ## initializing spider
        ## opening db connection
        self.client = pymongo.MongoClient(self.mongo_uri)
        self.db = self.client[self.mongo_db]

    def close_spider(self, spider):
        ## clean up when spider is closed
        self.client.close()

    def process_item(self, item, spider):
        ## how to handle each post
        self.db[self.collection_name].insert(dict(item))
        logging.debug("Post added to MongoDB!")
        return item