如何在Scrapy项目中使用PyMongo MongoDB插入新记录时删除重复项

pip install pymongo

MONGO_URI = 'mongodb://localhost:27017/'
MONGO_DATABASE = 'scrapy_data'
MONGO_COLLECTION = 'items'

from pymongo import MongoClient

class MongoDBPipeline(object):
    def __init__(self, mongo_uri, mongo_db, mongo_collection):
        self.mongo_uri = mongo_uri
        self.mongo_db = mongo_db
        self.mongo_collection = mongo_collection

    @classmethod
    def from_crawler(cls, crawler):
        return cls(
            mongo_uri=crawler.settings.get('MONGO_URI'),
            mongo_db=crawler.settings.get('MONGO_DATABASE'),
            mongo_collection=crawler.settings.get('MONGO_COLLECTION')
        )

    def open_spider(self, spider):
        self.client = MongoClient(self.mongo_uri)
        self.db = self.client[self.mongo_db]
        self.collection = self.db[self.mongo_collection]

    def close_spider(self, spider):
        self.client.close()

    def process_item(self, item, spider):
        # 根据需要进行去重操作
        self.collection.update_one(
            {'url': item['url']},  # 根据唯一标识字段进行去重，这里假设使用url字段
            {'$set': dict(item)},
            upsert=True
        )
        return item

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