Difference between revisions of "Web scrape troubleshooting"

From LemonWiki共筆
Jump to navigation Jump to search
m
(One intermediate revision by the same user not shown)
Line 48: Line 48:
 
== Before start to web scrpae ==
 
== Before start to web scrpae ==
  
* Are they offer datasets?
+
* Are they offer datasets? e.g. open data
 
* Are they offer [https://en.wikipedia.org/wiki/Application_programming_interface API] (Application programming interface)?
 
* Are they offer [https://en.wikipedia.org/wiki/Application_programming_interface API] (Application programming interface)?
  
 +
'''How to find the unofficial (3rd-party) web crawler?''' Search keyword strategy suggested as follows:
 +
* ''target website'' + crawler
 +
* ''target website'' + bot
 +
* ''target website'' + download
  
 
== Further reading ==
 
== Further reading ==

Revision as of 11:28, 8 October 2020

List of technical issues

  1. Content of web page was changed (revision): The expected web content (of specified DOM element) became empty.
    • Multiple sources of same column such as different HTML DOM but have the same column value.
    • Backup the HTML text of parent DOM element
    • (optional) Complete HTML file backup
  2. The IP was banned from server
  3. CATCHA
  4. AJAX
  5. The web page needed to signed in
  6. Blocking the request without Referer or other headers.
  7. Connection timeout during a http request. e.g. In PHP default_socket_timeout is 30 seconds[1][2].
  8. Language and URL-encodes string
  9. Data cleaning issues e.g. Non-breaking space or other Whitespace character
Difficulty in implementing Approach Comments
easy Url is the resource of dataset
more difficult Url is the resource of dataset. Require to simulate post form submit with the form data or user agent Using HTTP request and response data tool or PHP: cURL
more difficult Require to simulate the user behavior on browser such as click the button, submit the form and obtain the file finally. Using Selenium or Headless Chrome
difficult Ajax

Before start to web scrpae

  • Are they offer datasets? e.g. open data
  • Are they offer API (Application programming interface)?

How to find the unofficial (3rd-party) web crawler? Search keyword strategy suggested as follows:

  • target website + crawler
  • target website + bot
  • target website + download

Further reading

References


Troubleshooting of ...

Template