How do I get the current absolute URL in Ruby on Rails?

In Ruby on Rails, you often need to retrieve the full, absolute URL to perform redirects, perform analytics, or generate links that include the complete path (protocol, domain, and query parameters). Fortunately, Rails provides methods to access the entire URL directly from the request object.

Using `request.original_url`

The simplest and most reliable approach is to use request.original_url. This method returns the complete URL, including the protocol (http:// or https://), host, port, path, and query parameters.

def show
  # Full absolute URL, e.g. "https://www.example.com/articles/5?view=full"
  current_url = request.original_url
  puts current_url
end

Why `request.original_url`?

Preserves Query Parameters: If your URL includes something like ?search=ruby&sort=desc, request.original_url will include those parameters.
Accurate in Most Scenarios: request.original_url is generally the most up-to-date reflection of the client’s requested URL, including any reverse proxies or load balancers (provided your Rails configuration is set correctly with config.action_controller.default_url_options).

Using `request.url`

request.url can also return the current URL, but it may handle trailing slashes differently in certain situations. For example:

def index
  current_url = request.url
  # e.g. "https://www.example.com/articles"
  puts current_url
end

If you’re not worried about subtle differences in how trailing slashes or query parameters are represented, request.url can be a convenient alternative.

Building the URL Manually

In some edge cases, you may want to build the absolute URL yourself:

def edit
  protocol  = request.protocol       # "https://"
  host_port = request.host_with_port # "www.example.com" or "localhost:3000"
  path      = request.fullpath       # "/articles/5/edit?admin=true"

  current_url = "#{protocol}#{host_port}#{path}"
  puts current_url
end

This approach can be useful if you need to modify or filter certain parts of the URL before using it.

Best Practices

Production vs. Development: Make sure you’ve configured your production environment correctly so Rails knows your actual domain and protocol (via config.action_mailer.default_url_options or reverse proxy settings, for example).
Security: When generating links from user input, ensure you’re sanitizing or validating that input to protect against malicious redirects.
Testing: In integration tests or feature tests, you can check the generated URL with your test environment’s domain configuration.

Further Learning

If you’re looking to level up your Ruby on Rails knowledge for interviews or to build robust web applications, check out these courses from DesignGurus.io:

Grokking the Coding Interview: Patterns for Coding Questions
Perfect for strengthening the algorithmic and problem-solving skills you’ll need alongside Rails development.
Grokking System Design Fundamentals
Ideal if you’re planning to create scalable Rails apps. Learn the foundational concepts of distributed systems and architectures.

If you want personalized feedback, consider a Coding Mock Interview or System Design Mock Interview with ex-FAANG engineers.

Conclusion

Retrieving the current absolute URL in Ruby on Rails is straightforward using the request object. For most scenarios, request.original_url is the best choice because it returns the full URL exactly as the client requested it, including query parameters. By mastering these methods, you’ll write more reliable and maintainable code in any Rails application.

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