How to get & build full URLs in Rails

There are some cases when you want to get a current request absolute URL. Thankfully, Rails got you covered on this one and provides a simple way for that:

request.original_url

This'll return an absolute full URL including schema, host, port, path, and query string, but without anchor though.

So, for a request to https://example.com/resource?q=first:

request.original_url # => https://example.com/resource?q=first
request.fullpath # => /resource?q=first
request.path # => /resource

Building full URL

When you need to build a full URL in controller views you can simply use the URL helpers provided by Rails:

post_url(@post)

But it's not that easy outside the request(controller/view) scope. For example, if you need to build a full URL inside a background job, Rails can't simply get the host for that from a request, since there's no request.

To make it work we need two things:

First, include URL helpers.

class MyJob < ApplicationJob
  include Rails.application.routes.url_helpers

  def perform(user)
    user_url(user)
    ...
  end
end

And then, set url options in app configuration:

# config/environments/production.rb
Rails.application.routes.default_url_options[:host] =  "example.com"
# And for email views
Rails.application.config.action_mailer[:host] = "example.com"

If you need to generate URLs for assets (for example images/icons in emails) you'll need to set asset_host as well:

# Need only if host is other than the one 
# that handles requests
config.action_controller.asset_host = 'example.com'

# Required since mailer has no request context 
# to get host address from
config.action_mailer.asset_host = 'example.com'