扩展 Mongoid 关系文档中的示例,假设我有三个类......
class Band
include Mongoid::Document
embeds_many :albums
end
class Album
include Mongoid::Document
field :name, type: String
embedded_in :band
embeds_many :tracks
end
class Track
include Mongoid::Document
field :name, type: String
field :length, type: String
embedded_in :album
end
如何将曲目从一张专辑移动到另一张专辑?我已经尝试了明显的...
~/Projects/mongoid_testing (development) > Band.last.albums.first.tracks.first.update_attribute :album_id, Band.last.albums.second.id
☘ MongoDB (8ms) [mongoid_testing_development::Bands] QUERY selector={"$query"=>{}, "$orderby"=>{:_id=>-1}} flags=[:slave_ok] limit=-1 skip=0 batch_size=nil fields=nil
☘ MongoDB (0ms) [mongoid_testing_development::Bands] QUERY selector={"$query"=>{}, "$orderby"=>{:_id=>-1}} flags=[:slave_ok] limit=-1 skip=0 batch_size=nil fields=nil
☘ MongoDB (0ms) [mongoid_testing_development::Bands] UPDATE selector={"_id"=>"51005ceb93e53c2eec000012"} update={"$set"=>{"albums.0.tracks.0.album_id"=>"51005d2993e53c2eec000017"}} flags=[]
=> true
~/Projects/mongoid_testing (development) > Band.last
☘ MongoDB (0ms) [mongoid_testing_development::Bands] QUERY selector={"$query"=>{}, "$orderby"=>{:_id=>-1}} flags=[:slave_ok] limit=-1 skip=0 batch_size=nil fields=nil
=> #<Band:0x007fa22725b1f8> {
:_id => "51005ceb93e53c2eec000012",
:albums => [
[0] {
"_id" => "51005d2293e53c2eec000016",
"tracks" => [
[0] {
"_id" => "5107d87993e53c7191000007",
"album_id" => "51005d2993e53c2eec000017",
"title" => "Pipeline"
}
],
"name" => "Violater"
},
[1] {
"_id" => "51005d2993e53c2eec000017",
"name" => "Construction Time Again"
}
]
}
而且我已经尝试了不那么明显的...
class Track
...
def move_to(new_album_id)
_parent.albums.delete self
_root.albums.find(new_album_id).tracks.push self
end
end
但无论如何,我似乎都无法重新关联双嵌套嵌入文档。任何人都可以帮忙吗?谢谢。