OOP PYTHON：使用cls（）创建多个构造函数而不调用__init__

Question

我有一个Python类，它接受参数中的url并在新闻网站上启动爬虫。

完成对象的创建后，对象将存储在Elasticsearch集群中。

我想创建一个方法，接受输入Elasticsearch文档，并从中创建一个对象。

class NewsArticle():

    def __init__(self, url):
        self.url = url
        # Launch a crawler and fill in the other fields like author, date, ect ...

    @classmethod
    def from_elasticsearch(cls, elasticsearch_article):
        document = elasticsearch_article['_source']
        obj = cls(document['url'])
        obj.url = document['url']
        obj.author = document['author']
        .
        .
        .

问题在于，当我打电话......

# response is my document from elasticsearch
res = NewsArticle.from_elasticsearch(response)

...方法__init__将被调用并将启动我的抓取工具。无论如何它不会启动我的爬虫或调用init方法吗？

Answer 1

如何使用简单的if和默认参数crawl：

class NewsArticle():

    def __init__(self, url, crawl=True):
        self.url = url
        if crawl:
            # Launch a crawler and fill in the other fields like author, date, ect ...

    @classmethod
    def from_elasticsearch(cls, elasticsearch_article):
        document = elasticsearch_article['_source']
        obj = cls(document['url'], crawl=False)
        obj.url = document['url']
        obj.author = document['author']