What it is
Mechanize is a Python library for stateful programmatic web browsing. It allows you to automate interaction with websites, including filling forms, clicking links, and handling cookies and sessions, similar to a web browser.
Mechanize provides a browser-like interface in Python. You can navigate pages, select forms, fill them out, submit them, and retrieve responses. It supports handling cookies, redirects, and headers automatically.
Installation
pip install mechanizeGetting started
The smallest useful thing you can do with it, and what each part means.
import mechanize
br = mechanize.Browser()
br.open('http://example.com')
print(br.title())link = br.find_link(text='More information')
br.follow_link(link)
print(br.geturl())Advanced usage
Where the library earns its place over a simpler alternative.
br.select_form(nr=0)
br['username'] = 'myuser'
br['password'] = 'mypassword'
br.submit()br.set_cookiejar(mechanize.CookieJar())
br.open('http://example.com')br.addheaders = [('User-agent', 'Mozilla/5.0')]
br.open('http://example.com')br.set_handle_redirect(True)
br.open('http://example.com')Errors and fixes
The failures you are most likely to hit, and what actually resolves them.
- mechanize.HTTPError
- Check the response status code and ensure the URL is correct.
- mechanize.URLError
- Verify network connectivity and the validity of the URL.
- mechanize.LinkNotFoundError
- Ensure the link text exists on the page or use different selection criteria.
Best practices
- Always set a User-Agent to avoid being blocked by websites.
- Use CookieJar to manage sessions when scraping multiple pages.
- Avoid scraping websites without permission; respect robots.txt.
- Use proper exception handling for HTTP errors and timeouts.
- Combine Mechanize with BeautifulSoup for parsing page content efficiently.
Background
Why it exists, and what it was reacting to.
Mechanize was created as a Python port of Perl’s Mechanize module, enabling automated browsing and web scraping in Python. It is particularly useful for automating repetitive web tasks or interacting with websites that require form submissions.