如何創建has_many：通過關聯並設置聯接模型屬性

Question

我有這些模特

class Release < ActiveRecord::Base
  has_many :recordings, through: :release_recordings
  has_many :release_recordings, inverse_of: :release
end

class Recording < ActiveRecord::Base
  has_many :releases, through: :release_recordings
  has_many :release_recordings, inverse_of: :recording

  accepts_nested_attributes_for :release_recordings
end

class ReleaseRecording < ActiveRecord::Base
  belongs_to :release
  belongs_to :recording
end

我想以這種方式創建記錄，將position條目添加到聯接表中：

release.recordings.create!(name: name, release_recordings_attributes: { 0 => {position: position} })

問題在於，這最終試圖在release_recordings表中創建兩個記錄。 一種是release_id為NULL ，另一種是position NULL 。 當然，我只想創建一個沒有任何NULL字段的記錄。

我最終做了這個（它按預期工作）：

recording = release.recordings.create!(name: name)
recording.release_recordings.find_by_release_id(release).update_attributes!(position: position)

...但是當我應該已經引用了它時，查詢我剛剛創建的記錄似乎很愚蠢。

在為發行版本創建新的記錄記錄的同時，如何設置位置字段？

Answer 1

release.recordings.create!(name: name).release_recordings.create(position: position)

不確定這是否行得通..

class Recording < ActiveRecord::Base
  has_many :releases, through: :release_recordings
  has_many :release_recordings, inverse_of: :recording

  accepts_nested_attributes_for :release_recordings, reject_if: lambda { |release_recording| release_recording['release_id'].blank? }
end