Question

Event确实已保存，但"artists":[]为空，即使我选择了新表单中的多位艺术家。新表格的相关部分如下所示：

  <%= f.fields_for :event_artists do |fea| %>
    <%= fea.collection_select :artist_id, Artist.all, "id", "name", {include_blank: true}, {multiple: true} %>
  <% end %>

日志：

  Parameters: {"utf8"=>"✓", "authenticity_token"=>"OEh0j/cp35s/FABhsETxeQKnqZCKXrbZMpeeEE6P+KSM3QVF94zIluB1rqAD65ci5CP+R6tQS8V1f3SXIQ6Vtw==", "event"=>{"name"=>"", "date(1i)"=>"2016", "date(2i)"=>"7", "date(3i)"=>"22", "date(4i)"=>"01", "date(5i)"=>"55", "description"=>"", "venue_id"=>"1", "event_artists_attributes"=>{"0"=>{"artist_id"=>["", "1", "2"]}}}, "commit"=>"Create"}
Unpermitted parameter: artist_id

此控制器中允许使用此参数

def event_params
  params.require(:event).permit(:id, :name, :date, :venue_id, :description, { event_artists_attributes: [:artist_id] })
end

event_artist模型如下所示：

class EventArtist < ApplicationRecord
  belongs_to :event, optional: true
  belongs_to :artist
end

事件模型：

class Event < ApplicationRecord
  belongs_to :venue
  has_many :event_artists
  has_many :artists, through: :event_artists
  accepts_nested_attributes_for :event_artists, reject_if: :all_blank, allow_destroy: true

end

事件控制器：

  def create
    @event = Event.new(event_params)

    if @event.save
      render json: @event, status: :created, location: @event
    else
      render json: @event.errors, status: :unprocessable_entity
    end
  end

  def new
    @event = Event.new
    @artist = @event.event_artists.build
  end

Answer 1

你有一个不必要的哈希值event_artists_attributes。相反，使用：

  params.require(:event).permit(:id, :name, :date, :venue_id, :description, event_artists_attributes: [artist_id])

但是你有另一个问题。您尝试在仅EventArtist belongs_to Artist has_many artists, through: :event_artists Event上设置多个艺术家ID。由于您的def event_params params.require(:event).permit(:id, :name, :date, :venue_id, :description, artist_ids: []) end模型上有<%= fields_for…，因此您可以更改以下内容：

控制器：

<%= f.collection_select :artist_ids, Artist.all, "id", "name", 
                          {include_blank: true}, {multiple: true} %>

在表单中，删除{{1}}块并将其替换为：

{{1}}

Answer 2

试试这个：

  params.require(:event).permit(:id, :name, :date, :venue_id, :description, { event_artists_attributes: [artist_id: []] })

将数组输出保存到连接表（未允许的参数）

2 个答案: