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 config.action_mailer.default_url_options to solve this same bug elsewhere, but now I'm getting this error when trying to use a URL helper inside an RSpec spec. I have no idea where it's expecting default_url_options to be set.

 Failure/Error: listing_url(listing).should match(/\/\d+-\w+$/)
 RuntimeError:
   Missing host to link to! Please provide :host parameter or set default_url_options[:host]
 # ./spec/routing/listing_routing_spec.rb:9:in `block (3 levels) in <top (required)>'

This code has nothing to do with emails/ActionMailer, it just happens to need a URL instead of a path.

Any ideas?

Solution 1

Your::Application.routes.draw do
  default_url_options :host => "example.com"

  # ... snip ...
end

Somewhere in routes.rb :)

Solution 2

You need to add the following line at every environment:

config.action_mailer.default_url_options = { :host => "yourhost" }

That way, it can work in all environments and could be different from environment to environment. For example:

development.rb

config.action_mailer.default_url_options = { :host => "dev.yourhost.com" }

test.rb

config.action_mailer.default_url_options = { :host => "test.yourhost.com" }

production.rb

config.action_mailer.default_url_options = { :host => "www.yourhost.com" }

Solution 3

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

config/environments/development.rb

See this question and this question.

Solution 4

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.

Solution 5

When you use any listing_url method the full URL will be returned(not a relative one as normal). That's why rails is asking you for the host, to compute the whole URL.

How you can tell rails the host? You can do it in several ways:

1.Adding this option to each environment:

[/config/development.rb]
config.action_mailer.default_url_options = { host: "localhost:3000" }
[/config/test.rb]
config.action_mailer.default_url_options = { host: "localhost:3000" }
[/config/production.rb]
config.action_mailer.default_url_options = { host: "www.example.com" }

NOTE: If you are working inside a rails engine remember to do the same for your dummy app inside the engine tests: path_to_your_engine/test/dummy/config/environments/* because when you test the engine it's what rails is testing against.

2.Add the host option to the foo_url method like this:

listing_url(listing, host: request.host) # => 'http://localhost:3000/listings/1'

3.Not output the host with the option :only_path to true.

listing_url(listing, only_path: true ) # => '/listings/1'   

IMHO I don't see the point on this one because in this case I would use the listing_path method

View more solutions

Comments

[Jwan622]

What is the host anyway?

[Neil Middleton]

Not very good if you've got many different environments with differing URLs

[wejrowski]

Yeah what do you do if you have multiple env domains?

[d11wtq]

Presumably you just specify it for each URL instead, either in the route map, or in the url helper invocation: listing_url(listing, :host => "whatever.com").

[joelparkerhenderson]

Thanks, IMHO this is a better answer than the answer that uses routes.draw

[rxgx]

This answer does not help when using different domains and addresses other problems.

[Prathan Thananart]

In the config file for each respective environment, I add this custom option: config.domain = 'staging.myapp.com' (of course substitute in a correct domain name for each env). Then in routes.rb I'm free to use default_url_options host: Rails.application.config.domain and it will work in any environment. You're welcome.

[Stenerson]

Also make sure that you restart your rails server after you add this. The files under config/ are not automatically reloaded.

[drhenner]

Note: You can add a port also listing_url(listing, host: request.host, port: 3000)

[siannopollo]

A better approach would be to, within the routes file, do this: default_url_options Rails.application.config.action_mailer.default_url_options.

[Boti]

I have done very similar to this and setting the default_url_option for action_mailer won't help. The use case is similar to this: Rails.application.routes.url_helpers.message_image_url(2)

[Admin]

This and only this worked for getting the mailer to include the URL, but it breaks other link_to functions in my app.

[JosephK]

Did this; with or without www... prefixing the host name in production, I still got the same error. Added the route per @d11wtq, and it worked. Is there some Rails4 change that caused this behavior? I never saw it before the upgrade, and only in one particular mail-send (devise-automated), since.

[lucianosousa]

Step 1 always works for me and today, using the refinery-cms gem just step 2 save me. Thanks for the comment.

[curot]

This is a good solution for Rails 4, because it lets you set options specific to a controller if necessary.

[b1nary]

Can confirm that this does not work in my Rails 4 projects. Setting it in routes is simply no option.

[Jwan622]

Why does this error happen anyway? What is host: in the solution? What does that do?

[BooBailey]

Not working in Rails 5. Added default_url_options Rails.application.config.action_mailer.default_url_options though and that did the trick, as suggested by another commenter

[Joshua Pinter]

Great thinking, @pduesteler! I actually took this one step further and was able to add just one line in the config/environment.rb file to do this. And added answer that goes into detail: stackoverflow.com/a/48529627/293280 Thanks for pointing me in this direction.

[Eric D. Fields]

Setting up the config/environment.rb as you described was the key for getting my mailer to work in the console. Thank you!

[Joshua Pinter]

@EricD.Fields You're very welcome, Eric! I find this so useful that I think it should be built into the Rails core.

[courtsimas]

@Ryan you can just use environment vars to fix that

[courtsimas]

But what if you don't have the request context? Like in most things other than a controller?

[Levi Roberts]

Answer needs more information. Please describe what it is you're actually proposing as the solution.

[Garrett Motzner]

Here are some useful tips on How to Answer. I find them useful to refer to.

[Sandro L]

That would be Rails.application.default_url_options = Rails.application.config.action_mailer.default_url_options for Rails 5.2+

[Joshua Pinter]

Thanks, @SandroL! We're still on Rails 4.2 so haven't tested yet on later versions.

[Harry Wood]

A few people recommending this. I guess it's just that people tend to have action_mailer.default_url_options already configured for historical reasons, but isn't it more logical to set that based on application.default_url_options rather than the other way around? Why involve a bogus mailer reference when configuring how your website links work?

[Joshua Pinter]

@HarryWood I would agree, but for those of us that have been around since Rails 2, it began with action_mailer and so that's where our typical host and port configuration is stored.

[Stan]

Thank you! Using this outside of a controller (GraphQL direct upload mutation) so had to tweak it a bit, but works. I've been looking for this, thanks again @phoet :)

[siax]

Very useful answer because of mentioning the scenario when you are working with a rails engine! In my case I ran into the error when trying to execute a rake task that was using a model inside an engine. I loaded my action_mailer config into the engine like this and was finally able to run the task. MyEngine::Engine.config.action_mailer.default_url_options = Rails.application.config.action_mailer.default_url_options MyEngine::Engine.routes.default_url_options = Rails.application.config.action_mailer.default_url_options