Boosting search results for Facebook friends with fb_graph, omniauth, Sunspot and Solr

controller.rb

ids = current_user.facebook_friends if current_user
@search = Profile.solr_search do
  keywords params[:q] do
    boost_fields name: 10.0, user: 4.0
  end

  unless ids.blank?
    adjust_solr_params do |params|
      # See "bq (boost query)" in http://wiki.apache.org/solr/DisMaxQParserPlugin
      params[:bq] = "facebook_id_s:(#{ids.join(' OR ')})^10"
    end
  end

  paginate page: params[:page], per_page: page_size
end

@results = @search.results

model.rb

searchable do
  # some normal fields to search
  text :name, :description

  # index the ids as an array of strings (not text) as we want exact match, no stemming, etc
  string :facebook_id do
    user.facebook_id
  end
end

user.rb

# Returns a user associated with a facebook account.
def self.find_for_facebook_oauth(access_token, signed_in_resource=nil)
  data = access_token.extra.raw_info
  if user = User.where(:email => data.email).first
    user
  else # Create a user with a stub password.
    user = User.new email: data.email, first_name: data.first_name, last_name: data.last_name, password: Devise.friendly_token[0,20]

    facebook_id = data.id
    token = access_token.credentials.token

    user.facebook_info = { 'id' => facebook_id, 'token' => token }

    # in the future we could save the user and get the friends in a background worker if it's too slow
    fb_user = FbGraph::User.fetch facebook_id, access_token: token
    user.facebook_friends = fb_user.friends.map &:identifier

    user.save!
    user.confirm!
    user
  end
end