Tutorial of How to scrape (crawling) website's content using Scrapy Python

1. HOWTO SCRAPE
ANY WEBSITE
FOR FUN ;)
by Anton Rifco
anton.rifco@gmail.com
Some pictures taken from internet.
This article possess no copyright. Use it for your own purpose
July 2013
Monday, 15 July, 13

2. Let’s scrape this :)
Monday, 15 July, 13

3. Web Scraping,
a process of automatically collecting (stealing?)
information from the Internet
Monday, 15 July, 13

4. THETOOL
You need these tool to steal (uupss) those data:
Python (2.6 or 2.7) with some packages*
Scrapy** framework
Google Chrome with XPath*** review plugin
Computer, of course
and functional brain
*) http://doc.scrapy.org/en/latest/intro/install.html#requirements
**) refer to http://scrapy.org/ (this slides won’t cover the installation of those things)
***) I use “XPath helper” plugin
Monday, 15 July, 13

5. S C R A P Y
Not Crappy
Scrapy is an application framework for crawling
web sites and extracting structured data which can be used
for a wide range of useful applications, like data mining,
information processing or historical archival.
Monday, 15 July, 13

6. S C R A P Y
Not Crappy
Scrapy works by creating logical spiders that will crawl to any
website you like.
You define the logic of that spider, using Python
Scrapy uses a mechanism based on XPath expressions called
XPath selectors.
Monday, 15 July, 13

7. XPath is W3C standard to navigate through XML document
(so as HTML)
Here, XML documents are treated as trees of nodes.The
topmost element of the tree is called the root element.
For more, refer to: http://www.w3schools.com/xpath/
X P A T H
Monday, 15 July, 13

8. X P A T H
<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book>
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
</bookstore>
From example of nodes in the XML document above:
<bookstore> (root element node)
<author>J K. Rowling</author> (element node)
lang="en" (attribute node)
For more, refer to: http://www.w3schools.com/xpath/
Monday, 15 July, 13

9. Selecting Nodes
XPath uses path expressions to select nodes in an XML
document.The node is selected by following a path or steps
For more, refer to: http://www.w3schools.com/xpath/
Expression Result
nodename Selects all nodes with the name “nodename”
/ Do selection from the root
// Do selection from current node
. Select current node
.. Select parent node
@attr Select attributes of nodes
text() Select the value of chosen node
X P A T H
Monday, 15 July, 13

10. X P A T H
Predicate Expressions
Predicates are used to find a specific node or a node that contains a specific value.
Predicates are always embedded in square brackets.
Expression Result
/bookstore/book[1] Selects the first book element that is the child of the bookstore element.
/bookstore/book[last()] Selects the last book element that is the child of the bookstore element
/bookstore/book[last()-1] Selects the last but one book element that is the child of the bookstore
element
/bookstore/book[position()<3] Selects the first two book elements that are children of the bookstore
element
//title[@lang] Selects all the title elements that have an attribute named lang
//title[@lang='eng'] Selects all the title elements that have an attribute named lang with a value of
'eng'
/bookstore/book[price>35.00] Selects all the book elements of the bookstore element that have a price
element with a value greater than 35.00
Monday, 15 July, 13

11. X PAT H H E L P E R
By using XPATH Helper, you can easily get the XPath
expression of a given node in HTML doc. It will be enabled by
pressing <Ctrl>+<Shift>+X on Chrome
Monday, 15 July, 13

12. R E A L A C T I O N
Create Scrapy Comesg project
> scrapy startproject comesg
Then, it will create the following project directory structure
comesg/ /* This is Project root */
scrapy.cfg /* Project config file */
comesg/
__init__.py
items.py /* Definition of Items to scrap */
pipelines.py /* Pipeline config for advance use*/
settings.py /* Advance setting file */
spiders/ /* Directory to put spiders file */
__init__.py
...
Monday, 15 July, 13

13. R E A L A C T I O N
Define the Information Items that we want to scrap
Click any of place, will open its details
So, of all those data, we want to collect:
name of places,
photo,
description,
address (if any), contact number (if any), opening hours (if any),
website (if any), and video (if any)
Monday, 15 July, 13

14. from scrapy.item import Item, Field
class ComesgItem(Item):
# define the fields for your item here like:
name = Field()
photo = Field()
desc = Field()
address = Field()
contact = Field()
hours = Field()
website = Field()
video = Field()
On items.py, write the following:
I t e m s D e f i n i t i o n
Monday, 15 July, 13

15. R E A L A C T I O N
Basically, here is our strategy
1. Implements first spider that will get
url of the listed items
2. Crawl to that url one by one
3. Implements second spider that will
fetch all the required data
Monday, 15 July, 13

16. class AttractionSpider(CrawlSpider):
! name = "get-attraction"
! allowed_domains = ["comesingapore.com"] ## Will never go outside playground
! start_urls = [ ## Starting URL
! ! "http://comesingapore.com/travel-guide/category/285/attractions"
! ]
! rules = ()
! def __init__(self, name=None, **kwargs):
! ! super(AttractionSpider, self).__init__(name, **kwargs)
! ! self.items_buffer = {}
! ! self.base_url = "http://comesingapore.com"
! ! from scrapy.conf import settings
! ! settings.overrides['DOWNLOAD_TIMEOUT'] = 360 ## prevent too early timeout
! def parse(self, response):
! ! print "Start scrapping Attractions...."
! ! try:
! ! ! hxs = HtmlXPathSelector(response)
## XPath expression to get the URL of item details
! ! ! links = hxs.select("//*[@id='content']//a[@style='color:black']/@href")
! ! !
! ! ! if not links:
! ! ! ! return
! ! ! ! log.msg("No Data to scrap")
! ! ! for link in links:
! ! ! ! v_url = ''.join( link.extract() )
! ! ! ! ! ! ! !
! ! ! ! if not v_url:
! ! ! ! ! continue
! ! ! ! else: ## If valid URL, continue crawl those URL
! ! ! ! ! _url = self.base_url + v_url
## real work handled by second spider
! ! ! ! ! yield Request( url= _url, callback=self.parse_details )
! ! except Exception as e:
! ! ! log.msg("Parsing failed for URL {%s}"%format(response.request.url))
F i r s t s p i d e r
Monday, 15 July, 13

17. def parse_details(self, response):
! ! print "Start scrapping Detailed Info...."
! ! try:
! ! ! hxs = HtmlXPathSelector(response)
! ! ! l_venue = ComesgItem()
! ! ! v_name = hxs.select("/html/body/div[@id='wrapper']/div[@id='page']/div[@id='page-bgtop']/div[@id='page-bgbtm']/
div[@id='content']/div[3]/h1/text()").extract()
! ! ! if not v_name:
! ! ! ! v_name = hxs.select("/html/body/div[@id='wrapper']/div[@id='page']/div[@id='page-bgtop']/div[@id='page-
bgbtm']/div[@id='content']/div[2]/h1/text()").extract()
! ! !
! ! ! l_venue["name"] = v_name[0].strip()
! ! !
! ! ! base = hxs.select("//*[@id='content']/div[7]")
! ! ! if base.extract()[0].strip() == "<div style="clear:both"></div>":
! ! ! ! base = hxs.select("//*[@id='content']/div[8]")
! ! ! elif base.extract()[0].strip() == "<div style="padding-top:10px;margin-top:10px;border-top:1px dotted #DDD;">n
You must be logged in to add a tipn </div>":
! ! ! ! base = hxs.select("//*[@id='content']/div[6]")
! ! ! x_datas = base.select("div[1]/b").extract()
! ! ! v_datas = base.select("div[1]/text()").extract()
! ! ! i_d = 0;
! ! ! if x_datas:
! ! ! ! for x_data in x_datas:
! ! ! ! ! print "data is:" + x_data.strip()
! ! ! ! ! if x_data.strip() == "<b>Address:</b>":
! ! ! ! ! ! l_venue["address"] = v_datas[i_d].strip()
! ! ! ! ! if x_data.strip() == "<b>Contact:</b>":
! ! ! ! ! ! l_venue["contact"] = v_datas[i_d].strip()
! ! ! ! ! if x_data.strip() == "<b>Operating Hours:</b>":
! ! ! ! ! ! l_venue["hours"] = v_datas[i_d].strip()
! ! ! ! ! if x_data.strip() == "<b>Website:</b>":
! ! ! ! ! ! l_venue["website"] = (base.select("div[1]/a/@href").extract())[0].strip()
! ! ! ! ! i_d += 1
! ! ! !
! ! ! v_photo = base.select("img/@src").extract()
! ! ! if v_photo:
! ! ! ! l_venue["photo"] = v_photo[0].strip()
! ! ! v_desc = base.select("div[3]/text()").extract()
! ! ! if v_desc:
! ! ! ! desc = ""
! ! ! ! for dsc in v_desc:
! ! ! ! ! desc += dsc
! ! ! ! l_venue["desc"] = desc.strip()
S e c o n d s p i d e r
Monday, 15 July, 13

18. R E A L A C T I O N
Run the Project
> scrapy crawl get-attraction -t csv -o attr.csv
In the end, it produces file attr.csv with the scraped data,
like following:
> head -3 attr.csv
website,name,photo,hours,contact,video,address,desc
http://www.tigerlive.com.sg,TigerLIVE,http://tn.comesingapore.com/img/others/240x240/f/6/0000246.jpg,Daily
from 11am to 8pm (Last admission at 6.30pm).,(+65) 6270 7676,,"St. James Power Station, 3 Sentosa Gateway,
Singapore 098544",
http://www.zoo.com.sg,Singapore Zoo,http://tn.comesingapore.com/img/others/240x240/6/2/0000098.jpg,Daily
from 8.30am - 6pm (Last ticket sale at 5.30pm),(+65) 6269 3411,http://www.youtube.com/embed/p4jgx4yNY9I,"80
Mandai Lake Road, Singapore 729826","See exotic and endangered animals up close in their natural habitats in
the . Voted the best attraction in Singapore on Trip Advisor, and considered one of the best zoos in the
world, this attraction is a must see, housing over 2500 mammals, birds and reptiles.
Monday, 15 July, 13

19. Get the complete Project code @
https://github.com/antonrifco/comesg
Monday, 15 July, 13

20. THANKYOU!
- Anton -
Monday, 15 July, 13