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Scrapy Settings

Introduction​

In this tutorial, we will delve into the world of Scrapy settings. As you learn more about Scrapy and start to work on complex projects, fine-tuning and managing your Scrapy settings become increasingly important. These settings allow you to customize the behavior of your Scrapy project to suit your needs.

What are Scrapy Settings?​

Scrapy settings are a collection of key-value pairs that define how Scrapy behaves when running your spiders. These settings can control aspects ranging from concurrency limits, middleware, pipelines, logging level, to handling cookies and much more.

Where are Scrapy Settings?​

In a typical Scrapy project, settings are located in the settings.py file in your project directory. This file is automatically created when you start a new Scrapy project with the scrapy startproject command.

How to Use Scrapy Settings?​

Scrapy settings are used by assigning values to uppercase variables. For example, to set the download delay for your Scrapy project, you can modify the DOWNLOAD_DELAY setting in your settings.py file like so:

DOWNLOAD_DELAY = 3

In the above example, Scrapy will pause for 3 seconds between consecutive requests.

Overriding Scrapy Settings​

There are scenarios where you might want to change settings for a particular spider, without changing your global settings. Scrapy allows you to override global settings for an individual spider. This can be done in the spider's constructor or in the custom_settings attribute.

Here's an example:

class MySpider(scrapy.Spider):
    name = "my_spider"
    custom_settings = {
        'DOWNLOAD_DELAY': 2,
    }

In the above example, the download delay for MySpider is 2 seconds, even if the DOWNLOAD_DELAY in the settings.py file is set to a different value.

Important Scrapy Settings​

While there are many Scrapy settings, we'll cover some of the most commonly used ones here.

  • DOWNLOAD_DELAY: This setting is used to throttle the crawling speed to avoid hitting servers too hard.

  • CONCURRENT_REQUESTS: This is the maximum number of concurrent (i.e., simultaneous) requests that will be performed by the Scrapy downloader.

  • COOKIES_ENABLED: This setting determines whether cookies should be enabled in the Scrapy project.

  • ROBOTSTXT_OBEY: This setting dictates whether your spiders should obey the rules defined in the robots.txt file of the website you're crawling.

  • ITEM_PIPELINES: This setting allows you to enable your item pipelines and determine the order in which they run.

  • DOWNLOADER_MIDDLEWARES: This setting allows you to enable your downloader middleware and determine the order in which they run.

Conclusion​

Scrapy settings are an essential part of any Scrapy project, allowing you to fine-tune how your spiders behave and interact with the websites they're crawling. By correctly using and managing your settings, you can ensure that your spiders are respectful to servers, efficient, and effective in extracting the data you need.

Next time, you find yourself needing to customize your Scrapy project's behavior, remember to check the Scrapy settings. You might find just the setting you need!