CSS Images in Email With Rails 3

I'm trying to send out an email with Rails 3 and Action Mailer. The email goes out fine, but I want it to be HTML formatted with some basic styling which includes background images. I understand that the images might get blocked until the user allows them to be shown, but I still think it would be best to link to the images on my web server.

The email template called registration_confirmation.html.erb starts out like this:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Untitled Document</title>
<style type="text/css">
body {
    background: url(/images/mainbg_repeat.jpg) top repeat-x #cfcfcf;
    margin: 0px 0px 0px 0px;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 12px;
    color: #565656;
}

What is the best way to get the url link for the background image to have the full host included so that the background will show up in the email?

In response to my other answer, @Kevin wrote:

Thanks for the answer, I did think of doing something like that but I don't think it's possible with the way I have it setup. The mailer call is happening in a after_create call in a model rather than in a controller so I don't think I have access to the request object as you mentioned (or am I mistaken). I do have this in my mailer initializer: ActionMailer::Base.default_url_options[:host] = "localhost:3000" Can I somehow use that hos parameter in my mailer to make it work?

The answer is yes. All rails url-construction helpers should use these defualt_url_options. In addition to setting the :host, you should also force it to use absolute urls by settings this option:

ActionMailer::Base.default_url_options[:only_path] = false

Also, set the asset host like this:

config.action_mailer.asset_host = 'http://localhost:3000'

Then just use the image_path helper instead of hand-writing the url, like this:

<style type="text/css">
body {
    background: url(<%= image_path('mainbg_repeat.jpg') %>) top repeat-x #cfcfcf;
}
</style>

NOTE: Setting default_url_options directly like that is deprecated. Here's the new way to do it:

config.action_mailer.default_url_options = {
    :host => 'localhost:3000',
    :only_path => false
}

Pass your request host as a parameter to the mailer method, and then pass it from the method to the view. So, for example, your mailer method might look like this (example lifted from rails docs and modified here):

class UserMailer < ActionMailer::Base
  default :from => "notifications@example.com"

  def registration_confirmation(user, host)
    @user = user
    @host = host
    mail(:to => user.email, :subject => "Welcome to My Awesome Site")
  end
end

You would call it like this:

def some_action
    UserMailer.registration_confirmation(@user, request.host).deliver
end

Then in your view, you would just use the @host:

<style type="text/css">
body {
    background: url(http://<%= @host %>/images/mainbg_repeat.jpg) top repeat-x #cfcfcf;
}
</style>

This is all assuming the image server is the same as the server running the request. If the image server is hosted elsewhere, you have to output a constant here. You could put something like this in lib/settings.rb:

module Settings
  IMAGE_HOST = 'superawesome.images.com'
end

Then in your view, you'd just output the constant there, like this:

<style type="text/css">
body {
    background: url(http://<%= Settings::IMAGE_HOST %>/images/mainbg_repeat.jpg) top repeat-x #cfcfcf;
}
</style>

If you do not care about performance, the roadie gem can handle urls in the stylesheets for you.

来源：https://stackoverflow.com/questions/7520936/css-images-in-email-with-rails-3

标签

ruby-on-rails

actionmailer

html-email