How do I pass parameters to a Scrapy spider?

In Scrapy, you can pass parameters to Spiders by using the custom settings of Scrapy Spider. You can use the __init__ method of the Spider class to accept parameters.

Here is how you can do it:

import scrapy

class MySpider(scrapy.Spider):
    name = 'myspider'

    def __init__(self, category=None, *args, **kwargs):
        super(MySpider, self).__init__(*args, **kwargs)
        self.start_urls = ['http://www.example.com/categories/%s' % category]

In the above code, the __init__ method is used to accept the parameters. The category parameter is passed to the Scrapy spider and used to construct the start_urls.

Now, when you run the Scrapy spider, you can pass the parameter from the command line:

scrapy crawl myspider -a category=electronics

In the above command, myspider is the name of the Spider and category is the parameter being passed to the Spider. The -a option is used to pass parameters to the Spider.