Action Mailer Previews

When changing code in mailers, updating the corresponding mailer preview is easily forgotten.

Mailer previews can be tested like other code as well and I sometimes add the following test to test suites:

# Make sure to...

One option is to use partials. Or you can set the @template field to the name of another action:

class Mailer < ActionMailer::Base
  def foo
    subject "Hello World"
  end
  
  def bar
    subject "Hello Universe"

...

Rails 6 includes a WYSIWYG editor, Action Text. It works out of the box quite well, but chances are that you want to add some custom functionality. This card contains some tips how to ach...

Rails is split into a large number of (sub-) frameworks.

The most important and central of those are

• activesupport (extends the Ruby standard library)
• activerecord / activemodel (ORM for Rails)
• actionview / actionpack (controller / views)
  ...

When you generate a URL in a mailer view, ActionMailer will raise an error unless you previously configured it which hostname to use.

There are t...

When HTTP clients make an request they can define which response formats they can process. They do it by adding a header to the HTTP request like this:

Accept: application/json

This means the client will only understand JSON respon...

In Rails, we usually have a mailer setup like this:

class MyMailer < ActionMailer::Base

  def newsletter
    mail to: 'receiver@host.tld',
      from: 'sender@host.tld',
      subject: 'My mail'
  end

end

If you want to preview you...

Put the line below in the respective env.rb file to make your action controllers raise an ActionController::UnpermittedParameters error when strong params are not valid. This might come in handy when you are implementing an API and you want to...

Remember that your controller actions share the same method space with private methods defined in ActionController::Base. If your controller behaves in super-weird ways, check that you don't overwrite some internal method with a controller action.