Controlling HTTP Requests with urllib Headers

The Python urllib module provides a powerful way to make HTTP requests in your code. One key aspect of controlling these requests is setting the appropriate HTTP headers. Headers allow you to specify important metadata about the request, like the user agent, authentication credentials, caching settings, and more.

Why Headers Matter

Headers are a crucial part of the HTTP protocol. They communicate essential information about the client making the request and what kind of response it expects back.

For example, setting the User-Agent header appropriately identifies the type of client making the call. Servers may respond differently based on this identification:

import urllib.request 

headers = {'User-Agent': 'My Python App'}

req = urllib.request.Request('http://example.com', headers=headers)

Headers are also used for authentication, caching, cookies, and other advanced usage.

Setting Headers in Urllib

The urllib.request.Request object accepts a headers parameter where you can pass in a dictionary of headers to apply. For example:

headers = {
  'Authorization': 'Bearer mytoken',
  'Accept': 'application/json',  
  'User-Agent': 'My App Name'
}

req = urllib.request.Request(url, headers=headers)

You can set headers individually or in batches like this. Some common headers to set include:

Conclusion

Properly controlling headers unlocks the full potential of urllib. It allows your application to identify itself, set the expected response format, handle authentication, and more. Spending time to learn how to set headers appropriately will level up your HTTP requests.