TIL: Easily Support Gravatars in Rails

We’re building some software where we’d like to display avatars for email contacts even if they aren’t users of our software. While Gravatar is a relic of Web 2.0, we’ve found that there are still a significant number of people who have their email addresses in that system.

Here’s how I streamlined displaying an avatar for an email address if it exists in the Gravatar system.

First I created a new Gravatarable concern in app/models/concerns:

module Gravatarable
  extend ActiveSupport::Concern

  # Check if an image exists for the associated email hash.
  # We cache this to avoid excessive HTTP calls.
  def gravatar?
    Rails.cache.fetch(gravatar_cache_key, expires_in: 2.weeks) do
      response = Net::HTTP.get_response(URI(gravatar_url))
      response.is_a?(Net::HTTPSuccess)
    end
  end

  # Gravatar's image request docs: 
  #   https://docs.gravatar.com/general/images/
  # 
  # In our case, we want the request to 404 if Gravatar has no
  # image associated with the email hash.
  def gravatar_url(size:48)
    "https://www.gravatar.com/avatar/#{gravatar_id}?s=#{size}&d=404"
  end

  private

  def gravatar_cache_key
    "Sender.email_address.#{email_address.downcase}.gravatar?"
  end

  def gravatar_id
    Digest::MD5::hexdigest(email_address.downcase)
  end

end

This concern gets included in our Contact model. It can be included in any model that has an email_address method:

class Contact < ApplicationRecord
  include Gravatarable
  ...
end

Then a simple helper method can be used to display the avatar:

module ApplicationHelper
  def avatar_for(contact, size:, alt: contact.name, hidden: false)
    avatar_attributes = {
      alt: alt,
      title: alt,
      aria: { hidden: hidden },
      width: size,
      height: size,
      class: 'avatar'
    }

    image_src = contact.gravatar? ? 
                  contact.gravatar_url(size: size) : 
                  'avatar-default.png'
    image_tag(image_src, avatar_attributes)
  end