Web scrape troubleshooting: Difference between revisions

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* Are they offer datasets?
* Are they offer datasets?
* 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)?
== Skill tree of web scraping ==
Data extraction
* How they build the website
** Understanding the navigation system ★★☆☆☆
** Parse the sitemap XML file ★★☆☆☆
* Understnding the web technology
** HTTP GET/POST ★★☆☆☆
** CSS seletor and DOM (Document Object Model) elements ★★☆☆☆
** AJAX (Asynchronous JavaScript and XML) ★★★☆☆
* Using API to retrieve data ★★☆☆☆
* Parse remote files to retrieve data ★★☆☆☆
* Using unofficial method to retrieve data
** [https://curl.haxx.se/ curl] command or [https://www.gnu.org/software/wget/manual/wget.html GNU Wget] command ★★☆☆☆
** [https://www.selenium.dev/ SeleniumHQ Browser Automation] ★★★☆☆
* Forum submit
** submit the from without loggin ★★☆☆☆
** submit the from after logged the account ★★★☆☆
* Etiquette of web scraping
** Limit ot web request ★★☆☆☆
* Tom and Jerry
** VPN and proxy ★★☆☆☆
** Decode the [https://en.wikipedia.org/wiki/CAPTCHA CAPTCHA] ★★★★☆
** Decentralized web scraping ★★★★☆
Data transforming
* Data cleaning e.g. unprintable characters ★★☆☆☆
* Selection of database engine ★★★☆☆


== Further reading ==
== Further reading ==

Revision as of 12:03, 23 August 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?
  • Are they offer API (Application programming interface)?

Skill tree of web scraping

Data extraction

  • How they build the website
    • Understanding the navigation system ★★☆☆☆
    • Parse the sitemap XML file ★★☆☆☆
  • Understnding the web technology
    • HTTP GET/POST ★★☆☆☆
    • CSS seletor and DOM (Document Object Model) elements ★★☆☆☆
    • AJAX (Asynchronous JavaScript and XML) ★★★☆☆
  • Using API to retrieve data ★★☆☆☆
  • Parse remote files to retrieve data ★★☆☆☆
  • Using unofficial method to retrieve data
  • Forum submit
    • submit the from without loggin ★★☆☆☆
    • submit the from after logged the account ★★★☆☆
  • Etiquette of web scraping
    • Limit ot web request ★★☆☆☆
  • Tom and Jerry
    • VPN and proxy ★★☆☆☆
    • Decode the CAPTCHA ★★★★☆
    • Decentralized web scraping ★★★★☆

Data transforming

  • Data cleaning e.g. unprintable characters ★★☆☆☆
  • Selection of database engine ★★★☆☆

Further reading

References

  1. ↑ PHP: Runtime Configuration - Manual
  2. ↑ libcurl - Error Codes


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