Ruby on rails Mongoid“；“充当树的角色”；vs.“；递归地“u嵌入”u many“；vs.“；mongoid树“；

我对mongoid和rails很陌生。因此，我很难让树结构正常工作：

我找到了三个“解决方案”来构建

mongoid树（最真实的树）

mongoid提供了解决方案 递归地嵌入更多

mongoid_充当_树

我的目标是为musicstyles创建一个树，它可以被引用/嵌入到不同的模型中

• -房子
• ---科技馆
• ---最小房屋
• -民间的
• ---非洲人
• ---亚洲人
• -金属
• ---重金属
• ---死亡金属

我的模型现在看起来像这样：

class Musicstyle
  include Mongoid::Document
  include Mongoid::Timestamps

  include Mongoid::Tree # mongoid-tree Version
  recursively_embeds_many # mongoids version itself

  field :musicstyle, type: String
  field :description, type: String
  field :parent
end

class Musicstyle
  include Mongoid::Document
  include Mongoid::Timestamps
  include Mongoid::Tree

  field :musicstyle, type: String
  field :description, type: String
end

# Usage example
musicstyle = Musicstyle.find(...)
musicstyle.children # This music style's children
musicstyle.parent   # This music style's parent

class Musicstyle
  include Mongoid::Document
  include Mongoid::Timestamps
  recursively_embeds_many

  field :musicstyle, type: String
  field :description, type: String
end

# Usage example
musicstyle = Musicstyle.find(...)
musicstyle.child_musicstyles # This music style's children
musicstyle.children.first.parent_musicstyle # The first child's parent (as you can't use find to get an embedded music style)

那景色呢

<div class="field">
    <%= f.label :parent %>
    <%= f.select :parent,
                 Musicstyle.all.map { |m| [m.musicstyle, m._id] },
                 {:include_blank => "Select a parent (if needed)"} %>
</div>

“选择父项（如果需要）”}%>

我现在搜索了几个小时寻找一个有效的例子，但没有成功

也许有人能给我一些代码，让我更好地理解

任何帮助都会使我高兴

---

很多很多提前感谢

您不能使用

mongoid树

和

递归地将许多

嵌入在一起。您必须在使用引用的树（

mongoid树

）或嵌入的树（

递归地嵌入多个

）之间进行选择。如果你想在其他模型中嵌入树，我推荐后者。如果您想参考其他模型的音乐风格（例如，将它们作为类别使用，并使它们具有许多不同的艺术家），我建议使用

mongoid树

方法。在这两种情况下，您都不需要

parent

字段

因此，您使用

mongoid树的示例可能如下所示：

class Musicstyle
  include Mongoid::Document
  include Mongoid::Timestamps

  include Mongoid::Tree # mongoid-tree Version
  recursively_embeds_many # mongoids version itself

  field :musicstyle, type: String
  field :description, type: String
  field :parent
end

class Musicstyle
  include Mongoid::Document
  include Mongoid::Timestamps
  include Mongoid::Tree

  field :musicstyle, type: String
  field :description, type: String
end

# Usage example
musicstyle = Musicstyle.find(...)
musicstyle.children # This music style's children
musicstyle.parent   # This music style's parent

class Musicstyle
  include Mongoid::Document
  include Mongoid::Timestamps
  recursively_embeds_many

  field :musicstyle, type: String
  field :description, type: String
end

# Usage example
musicstyle = Musicstyle.find(...)
musicstyle.child_musicstyles # This music style's children
musicstyle.children.first.parent_musicstyle # The first child's parent (as you can't use find to get an embedded music style)

您的示例仅使用递归方式嵌入了许多

，如下所示：

class Musicstyle
  include Mongoid::Document
  include Mongoid::Timestamps

  include Mongoid::Tree # mongoid-tree Version
  recursively_embeds_many # mongoids version itself

  field :musicstyle, type: String
  field :description, type: String
  field :parent
end

class Musicstyle
  include Mongoid::Document
  include Mongoid::Timestamps
  include Mongoid::Tree

  field :musicstyle, type: String
  field :description, type: String
end

# Usage example
musicstyle = Musicstyle.find(...)
musicstyle.children # This music style's children
musicstyle.parent   # This music style's parent

class Musicstyle
  include Mongoid::Document
  include Mongoid::Timestamps
  recursively_embeds_many

  field :musicstyle, type: String
  field :description, type: String
end

# Usage example
musicstyle = Musicstyle.find(...)
musicstyle.child_musicstyles # This music style's children
musicstyle.children.first.parent_musicstyle # The first child's parent (as you can't use find to get an embedded music style)

最好的

---

Benedikt

我在这里发布了我的解决方案：

模型

控制器

def new
    @musicstyle = Musicstyle.new
    @all_musicstyles = Musicstyle.all
end
def create
    if params[:musicstyle][:parent_musicstyle]
       parent = Musicstyle.find(params[:musicstyle].delete(:parent_musicstyle))
       parent.child_musicstyles.create(params[:musicstyle])
    end
    @musicstyle = Musicstyle.new(params[:musicstyle])
end

看法