我有两个模型,它们通过第三个模型连接:
Playlist has_many :song_in_playlists, :dependent => :destroy
has_many :songs, :through => :song_in_playlists
Song has_many :song_in_playlists, :dependent => :destroy
has_many :playlists, :through => :song_in_playlists
song_in_playlist
表简单地列出了playlist_id
、song_id
以及track_number
。
当调用/playlists/1.json
时,我想得到一个json哈希,它包含播放列表的属性,并且里面有另一个哈希,其中包含歌曲(如/songs.json
加上song_in_playlists
表项中的track_number
)。
根据Rails API,我应该能够通过以下操作实现这一点:
def show
@playlist = Playlist.find(params[:id])
[...]
respond_to do |format|
format.html # show.html.erb
format.json { render json: @playlist.as_json(
:include => { :song_in_playlists => {
:only => :track_number, :include => :songs {
:except => [:dropbox_link, :local_path] } } }
) }
end
end
end
然而,我得到的是以下内容:
/home/sloth/audiomixer/app/controllers/playlists_controller.rb:30: syntax error, unexpected '{', expecting '}'
:only => :track_number, :include => :songs {
^
/home/sloth/audiomixer/app/controllers/playlists_controller.rb:31: syntax error, unexpected '}', expecting keyword_end
:except => [:dropbox_link, :local_path] } } }
^
/home/sloth/audiomixer/app/controllers/playlists_controller.rb:103: syntax error, unexpected $end, expecting keyword_end
所以我试着降低一点复杂性,调用
format.json { render json: @playlist.as_json(
:include => song_in_playlists {
:only => :track_number } ) }
但我也犯了类似的错误。当我把任何大括号放在括号之间时,Rails就会抱怨,尽管API文档的说明正好相反。
我真的不知道该尝试什么了:(
PS:Ruby 1.9.3,Rails 3.2.13
---编辑---好吧,我真的不知道为什么,但我得到这个是为了产生预期的输出:
format.json { render json: @playlist.as_json(
:include => { :song_in_playlists => {
:include => :song, :only => :track_number } } ) }
然而,当尝试在:song
和, :only
之间添加{ :except => [:dropbox_link, :local_path] }
时,我再次遇到同样的错误。。
这只是部分关于轨道
:include => song_in_playlists {:only => :track_number}
只是不是有效的ruby语法
这应该是
:include => {:song_in_playlists => {:only => :track_number}}
每次,密钥都是关联名称(song_in_playlists),值是包含密钥:only
、:except
或:include
中的一个或多个的散列
如果你想改变json中歌曲表的属性,那么你需要使用
format.json { render json: @playlist.as_json(
:include => { :song_in_playlists => {
:include => :song, :only => :track_number } } ) }
并将:song
替换为描述您想对歌曲做什么的散列,例如
format.json { render json: @playlist.as_json(
:include => {
:song_in_playlists => {
:include => {
:song => {
:except => [:dropbox_link, :local_path]
}
},
:only => :track_number
}
})}