を参考に：
http://developers.facebook.com/roadmap/offline-access-removal/#extend_token
私のコードは次のようになります。
fb = Koala::Facebook::API.new(access_token)
fb.graph_call("/oauth/access_token", {"client_id" => app_id, "client_secret" => app_secret, "grant_type" => "fb_exchange_token", "fb_exchange_token" => access_token })
戻り値には拡張トークンが含まれていますが、MultiJson::DecodeError をスローしていますが、
MultiJson::DecodeError: 387: unexpected token at 'access_token=long-lived_token&expires=5184000]'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/json-1.6.1/lib/json/common.rb:148:in `parse'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/json-1.6.1/lib/json/common.rb:148:in `parse'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/multi_json-1.0.3/lib/multi_json/engines/json_gem.rb:13:in `decode'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/multi_json-1.0.3/lib/multi_json.rb:65:in `decode'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/koala-1.3.0/lib/koala/api.rb:61:in `api'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/koala-1.3.0/lib/koala/api/graph_api.rb:421:in `graph_call'
from (irb):7
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/railties-3.1.3/lib/rails/commands/console.rb:45:in `start'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/railties-3.1.3/lib/rails/commands/console.rb:8:in `start'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/railties-3.1.3/lib/rails/commands.rb:40:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
]エラーの原因となっているエンディングを疑っています。これが Facebook のエラーなのか、それとも私の処理ミスなのかはわかりません。誰かが私を助けてくれれば感謝します。感謝！
代わりに Net::HTTP.get(uri) も使用してみました。しかし、以下のエラーが発生しました。
Errno::ECONNRESET: Connection reset by peer
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/protocol.rb:135:in `read_nonblock'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/protocol.rb:135:in `rbuf_fill'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/protocol.rb:116:in `readuntil'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/protocol.rb:126:in `readline'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/http.rb:2211:in `read_status_line'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/http.rb:2200:in `read_new'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/http.rb:1183:in `transport_request'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/http.rb:1169:in `request'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/http.rb:1073:in `request_get'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/http.rb:394:in `block in get_response'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/http.rb:627:in `start'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/http.rb:393:in `get_response'
from /usr/local/rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/net/http.rb:370:in `get'
from (irb):11
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/railties-3.1.3/lib/rails/commands/console.rb:45:in `start'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/railties-3.1.3/lib/rails/commands/console.rb:8:in `start'
from /usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/gems/railties-3.1.3/lib/rails/commands.rb:40:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
ファイアウォールか何かかわからない？