Rails: Missing host to link to! Please provide :host parameter or set default_url_options[:host]

Question

I have been googling for about 90 minutes now and still don\'t have an answer to this. Where do I set default_url_options? I\'ve already set it for conf

Answer 1

The host should be specified in each environment's config file. Eg:

config/environments/development.rb

See this question and this question.

Answer 2

Set default_url_options to use your action_mailer.default_url_options.

In each of your environment files (e.g. development.rb, production.rb, etc.) you can specify the default_url_options to use for action_mailer:

config.action_mailer.default_url_options = { host: 'lvh.me', port: '3000' }

However, these are not set for MyApp:Application.default_url_options:

$ MyApp::Application.config.action_mailer.default_url_options
#=> {:host=>"lvh.me", :port=>"3000"}

$ MyApp::Application.default_url_options
#=> {}

That's why you are getting that error in anything outside of ActionMailer.

You can set your Application's default_url_options to use what you defined for action_mailer in the appropriate environment file (development.rb, production.rb, etc.).

To keep things as DRY as possible, do this in your config/environment.rb file so you only have to do this once:

# Initialize the rails application
MyApp::Application.initialize!

# Set the default host and port to be the same as Action Mailer.
MyApp::Application.default_url_options = MyApp::Application.config.action_mailer.default_url_options

Now when you boot up your app, your entire Application's default_url_options will match your action_mailer.default_url_options:

$ MyApp::Application.config.action_mailer.default_url_options
#=> {:host=>"lvh.me", :port=>"3000"}

$ MyApp::Application.default_url_options
#=> {:host=>"lvh.me", :port=>"3000"}

Hat tip to @pduersteler for leading me down this path.

Answer 3

You can always pass host as a parameter to the URL helper:

listing_url(listing, host: request.host)