Include has_many through: relationship fails

With the following set of models:

class User < ActiveRecord::Base
    ...
    has_many :participations
    has_many :attempts, through: :participations
    has_many :completed_attempts, -> { completed }, through: :participations, source: :attempts
    ...
end

class Participation < ActiveRecord::Base
    ...
    belongs_to :user
    has_many :attempts
    ...
end

class Attempt < ActiveRecord::Base
    ...
    belongs_to :participation
    ...
end

the request GET /users/1?include=completed-attempts fails. completed-attempts.txt.

Likewise, GET /users/1?include=completed-attempts,attempts fails. completed-attempts_attempts.txt

However, as expected, GET /users/1?include=attempts works. attempts.txt

Changing the order, GET /users/1?include=attempts,completed-attempts, doesn't fail with a 500, however it returns the full list of Attempts for both the attempts and completed-attempts relationships. attempts_completed-attempts.txt

Querying the relations directly from the AR object works correctly for both attempts and completed_attempts.

まず、User、Participation、Attempt のモデル定義を使って、列挙された GET /users/1 リクエストを再現し、include のレスポンスを直接の ActiveRecord クエリと比較します。フィルタリングされた has_many-through リレーションの処理と、ネストされた include の順序を調査します。completed-attempts が完了した Attempt のみを返し、列挙されたすべてのリクエストで 500 が発生しなければ完了です。