Rails: How to get the last message creation time of a given user?

Question

User can have multiple messages:

class User < ActiveRecord::Base
  has_many :messages, :foreign_key => "publisher_id"
end

To get the latest message time I do:

class User < ActiveRecord::Base
  def last_message_time
    last_message = messages.max{ |m1, m2| m1.created_at <=> m2.created_at }
    last_message ? last_message.created_at : nil
  end
end

For some reason, I'm sure that there is a better way to do this.

How would you do this ?

Answer 1

This is a short version:

# Ruby < 2.3.0
def last_message_time
  messages.order(:created_at).last.try(:created_at)
end

# Ruby >= 2.3.0
def last_message_time
  messages.order(:created_at).last&.created_at
end

Update (thx @mnort9): Updated for Ruby > 2.3.0