Rails 4在數據庫中沒有保存的嵌套表單域

Question

我有用於輸入相冊以及屬於相冊的歌曲的表單。相冊正在保存到數據庫，但是單曲不能保存。

相冊模型

class Album < ActiveRecord::Base 
    belongs_to :user 
    has_many :songs, :dependent => :destroy 
    accepts_nested_attributes_for :songs 
    has_attached_file :image, :styles => { :large => "500x500>", :medium => "300x300>", :thumb => "100x100>" } 

    validates :image, presence: true 
    validates :title, presence: true 

    extend FriendlyId 
    friendly_id :title, use: :slugged 


end 

歌曲模型

class Song < ActiveRecord::Base 
    belongs_to :album 

    extend FriendlyId 
    friendly_id :title, use: :slugged 
end 

相冊控制器

class AlbumsController < ApplicationController 
    before_action :set_album, only: [:show, :edit, :update, :destroy] 
    before_action :authenticate_user!, except: [:index, :show] 
    before_filter :verify_is_admin, except: [:index, :show] 


    def index 
    @albums = Album.all.order("created_at DESC").paginate(:page => params[:page], :per_page => 8) 
    end 

    def show 
    end 

    def new 
    @album = current_user.albums.build 
    3.times { @album.songs.build } 
    end 

    def edit 
    end 

    def create 
    @album = current_user.albums.build(album_params) 
    if @album.save 
     redirect_to @album, notice: 'Album was successfully created.' 
    else 
     render action: 'new' 
    end 
    end 

    def update 
    if @album.update(album_params) 
     redirect_to @album, notice: 'Album was successfully updated.' 
    else 
     render action: 'edit' 
    end 
    end 

    def destroy 
    @album.destroy 
    redirect_to albums_url 
    end 


    private 

    def verify_is_admin 
     (current_user.nil?) ? redirect_to(root_path) : (redirect_to(root_path) unless current_user.admin?) 
    end 

    # Use callbacks to share common setup or constraints between actions. 
    def set_album 
     @album = Album.find_by_slug(params[:id]) 
    end 

    def correct_user 
     @album = current_user.albums.find_by(id: params[:id]) 
     redirect_to albums_path, notice: "Not authorized to edit this album" if @album.nil? 
    end 

    # Never trust parameters from the scary internet, only allow the white list through. 
    def album_params 
     params.require(:album).permit(:title, :image, :embed, :embed_html) 
    end 
end 

歌曲控制器

class SongsController < ApplicationController 
    before_action :set_song, only: [:show, :edit, :update, :destroy] 


    def index 
    @songs = Song.all 
    end 

    def show 
    end 

    def new 
    @song = Song.new 
    end 

    def edit 
    end 

    def create 
    @song = Song.new(song_params) 

    respond_to do |format| 
     if @song.save 
     format.html { redirect_to @song, notice: 'Song was successfully created.' } 
     format.json { render action: 'show', status: :created, location: @song } 
     else 
     format.html { render action: 'new' } 
     format.json { render json: @song.errors, status: :unprocessable_entity } 
     end 
    end 
    end 

    def update 
    respond_to do |format| 
     if @song.update(song_params) 
     format.html { redirect_to @song, notice: 'Song was successfully updated.' } 
     format.json { head :no_content } 
     else 
     format.html { render action: 'edit' } 
     format.json { render json: @song.errors, status: :unprocessable_entity } 
     end 
    end 
    end 

    def destroy 
    @song.destroy 
    respond_to do |format| 
     format.html { redirect_to songs_url } 
     format.json { head :no_content } 
    end 
    end 

    private 
    # Use callbacks to share common setup or constraints between actions. 
    def set_song 
     @song = Song.find(params[:id]) 
    end 

    # Never trust parameters from the scary internet, only allow the white list through. 
    def song_params 
     params.require(:song).permit(:title) 
    end 
end 

，這裏是爲新專輯視圖

<%= form_for @album, html: { multipart: true } do |f| %> 
    <% if @album.errors.any? %> 
    <div id="error_explanation"> 
     <h2><%= pluralize(@album.errors.count, "error") %> prohibited this album from being saved:</h2> 

     <ul> 
     <% @album.errors.full_messages.each do |msg| %> 
     <li><%= msg %></li> 
     <% end %> 
     </ul> 
    </div> 
    <% end %> 

    <div class="form-group"> 
    <%= f.label :Artwork %> 
    <%= f.file_field :image, class: "form-control" %> 
    </div> 

    <div class="form-group"> 
    <%= f.label :title %> 
    <%= f.text_field :title, class: "form-control" %> 
    </div> 

    <div class="form-group"> 
    <%= f.fields_for :songs do |builder| %> 
    <fieldset> 
     <%= builder.label :title, "Song" %><br /> 
     <%= builder.text_field :title, :rows => 3 %> 
    </fieldset> 
    <% end %> 
    </div> 

    <div class="form-group"> 
    <%= f.submit class: "btn btn-primary" %> 
    </div> 

<% end %> 

Answer 1

你需要告訴這首歌PARAMS你強參數的形式：

def album_params 
    params.require(:album).permit(:title, :image, :embed, :embed_html, 
           :songs_attributes => [:id, :_destroy, :title]) 
end 

不要忘了，包括所有歌曲的屬性是你想能夠更新。