To get a Gravatar you need to hash an email address with the MD5 algorithm.
MD5 is a part of the Ruby standard library. Rails loads it by default, but otherwise you will have to require it yourself.
This is a simple implementation.
Gravatar supports other features, such as ratings and sizes. But the code below just hashes an email and constructs the Gravatar URL.
It also sets a default image using the ?d param, in case you need a default image.
require 'digest/md5' # gravatar("firstname.lastname@example.org") def gravatar(email) base_url = "http://gravatar.com/avatar/" hashed_email = Digest::MD5.hexdigest(email) default_image = "?d=http://example.com/path/to/default-image.jpg" [base_url, hashed_email, default_image].join end
The image I used for the default doesn't exist. Replace it with your own default image.