Scrapy is a powerful Python framework for web scraping that provides a convenient way to extract data from websites. In this tutorial, we will show you how to create a Scrapy Spider using two different methods. But first, we should explain what exactly is a “spider”.
What is a Spider?
A spider is a program or script that systematically crawls web pages to extract data. In the context of web scraping, spiders are used to automate the process of gathering data from websites. A spider is designed to follow links on a website and extract relevant data from the web pages it visits.
The spider starts at a given URL, retrieves the HTML content of that page, and extracts the information it needs based on the defined rules. Spiders are the core of most web scraping frameworks, including Scrapy, and are essential for efficient and effective web scraping.
How to create a Spider manually?
The first method to create a spider is the “manual” method. This method takes a bit longer, but its better to understand what exactly you are doing with the spider code. Better to start with this first, then you can use the automatic method later.
Make sure you have a scrapy project setup, before following any of the below steps.
1. Import the necessary modules:
import scrapy
2. Define your spider class. This class should inherit from scrapy.Spider, which inherits some important functionality and functions that we will be using later. We must also include a name attribute, which is a unique identifier we can use to call our scrapy spider later. Two spiders must not share the same name.
class MySpider(scrapy.Spider):
name = 'myspider'
3. Define the start_urls attribute. This should be a list of URLs that the spider will start scraping from:
start_urls = ['http://example.com']
4. Define the allowed_domains attribute. This should be a list of domains that the spider is allowed to scrape. If the spider tries to scrape a URL that isn’t in one of these domains, it will be ignored:
allowed_domains = ['example.com']
5. Define the parse() method. This method is called when the spider starts scraping, and is where you will define what data you want to scrape from the website:
def parse(self, response):
# Your code here
6. In the parse() method, you can use Scrapy’s selectors to extract data from the website. For example, to extract all the links on a page, you could use:
links = response.css('a::attr(href)').getall()
7. Here is the code for the complete spider.
class MySpider(scrapy.Spider):
name = 'myspider'
start_urls = ['http://example.com']
allowed_domains = ['example.com']
def parse(self, response):
# Extract links
links = response.css('a::attr(href)').getall()
8. Run the following command in the terminal to execute the above spider.
scrapy crawl myspider
Make sure to call this command from the top-level folder in your scrapy project. If you have made a project called “tutorial”, there should be two tutorial folders, one within the other. Call this command from the outer one.
Having trouble following along? Check out our video tutorial instead!
Creating a Scrapy Spider using genspider
Creating a Scrapy spider using the genspider command is a quick and easy way to generate a basic spider template. With the command, you can specify the name of the spider and the starting URL, and Scrapy will generate a new spider file in your project directory with the specified name.
To create a new spider using genspider, open a terminal window and navigate to your Scrapy project directory. Then, use the following command:
scrapy genspider <spider_name> <start_url>Replace <spider_name> with the desired name of your spider, and <start_url> with the URL that you want the spider to start scraping from.
For example, if you want to create a spider named “example” that starts scraping from the URL “http://example.com“, you would use the following command:
scrapy genspider example http://example.com
Scrapy will then generate a new spider file called “example.py” in your project directory, with a basic spider template that includes the specified URL as the start_urls attribute. You can then customize the spider as needed to extract the data you want.
For example, using the following command:
scrapy genspider myspider https://example.comgenerates this:
import scrapy
class MySpider(scrapy.Spider):
name = 'myspider'
allowed_domains = ['example.com']
start_urls = ['https://example.com/']
def parse(self, response):
# Your code here
This marks the end of the “How to create a Scrapy Spider” tutorial. Any suggestions or contributions for CodersLegacy are more than welcome. Questions regarding the article content can be asked in the comments section below.
