Collector API Example

api_example.rb

class AbstractActivityCollector
  def run
    activities.each do |activity|
      persist_activity(activity)
    end
  end

  # To be implemented by subclasses
  #
  # Returns an array pending activities.
  def activities
    raise NotImplementedError
  end

  # To be implemented by subclass
  #
  # Returns the HTML for displaying the
  # activity.
  def view_for(activity)
    raise NotImplementedError
  end

  # Define where the activity originates from
  def self.source(src = nil)
    @source = src unless src.nil?
    @source
  end

  protected

  def persist_activity(activity)
    # Since we run the collectors frequently, it is very common to encounter
    # objects that we have already imported.  If this activity is a duplicate
    # of an existing object, then we skip importing this activity.
    return if activity.duplicate?

    unless activity.save
      Rails.logger.error("Failed to persist activity from raw data: #{raw_activity}.\nValidation errors: #{activity.errors}")
    end
  end

end



class TwitterCollector < AbstractActivityCollector

  source "Twitter"

  attr_reader :username

  def initialize(username)
    @username = username
  end

  def activities
    @activities ||= fetch_activities
  end

  def view_for(activity)
    activity.data[:text].gsub(/@\w+\b/) do |username|
      username_without_at_sign = username.delete('@')
      username_url = "http://twitter.com/#{username_without_at_sign}"
      "<a href=\"#{username_url}\">#{username}</a>"
    end
  end

  private

  def fetch_activities
    tweets = Twitter.user_timeline(username)
    tweets.map {|tweet| build_activity_from_tweet(tweet) }
  end

  def build_activity_from_tweet(tweet)
    Activity.new do |activity|
      activity.collector    = self
      activity.fingerprint  = tweet.id
      activity.created_at   = tweet.created_at

      activity.data = {
        :status_id  => tweet.id,
        :username   => tweet.user.screen_name,
        :text       => tweet.text
      }
    end
  end
end



class Activity
  include Mongoid::Document
  include Mongoid::Paranoia

  field :collector_name, :type => String
  field :fingerprint, :type => String
  field :data, :type => Hash
  field :created_at, :type => DateTime

  validates_presence_of :created_at

  def collector=(collector)
    self.collector_name = collector.class.name
  end

  def collector
    return unless collector_name
    collector_name.constantize
  end

  def source
    collector.source
  end

  def created_on
    return nil unless created_at
    created_at.to_date
  end

  def duplicate?
    duplicate_activities = self.class.where(:collector_name => self.collector_name, :fingerprint => self.fingerprint)
    duplicate_activities.exists? || duplicate_activities.deleted.exists?
  end
end