3

I am quite new to mongoid and rails. So I have some troubles to get an tree structure working:

I found three "solutions" to build

mongoid-tree (which is the most actual one) https://github.com/benedikt/mongoid-tree

and the mongoid provided solution recursively_embeds_more

mongoid_acts_as_tree https://github.com/saks/mongoid_acts_as_tree

my goal is to make a tree for musicstyles which can be referenced/embedded in different models.

  • -House
  • ---Tech House
  • ---Minimal House
  • -Folk
  • ---African
  • ---Asian
  • -Metal
  • ---Heavy Metal
  • ---Death Metal
  • .....

My Model looks now like this:

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

and the view

<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>

I searched now for hours for an working example, without success.

Maybe someone can offer me some lines of code for a better understanding

any help will make my day

many, many thanks in advance

4

2 回答 2

5

You can't use mongoid-tree and recursively_embeds_many together. You'll have to choose between a tree using references (mongoid-tree) or an embedded tree (recursively_embeds_many). If you want to embed the tree in other models I'd recommend the latter. If you want to reference music styles from other models (for example use them as categories and make them have many different artists) I'd recommend the mongoid-tree approach. In both cases you won't need the parent field.

So your example using mongoid-tree could look like this:

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

and your example using just recursively_embeds_many could look like this:

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)

Bests,

Benedikt

于 2012-07-04T06:49:35.607 回答
1

I had posted my solution here:

https://groups.google.com/forum/?fromgroups#!topic/mongoid/iF39R_hwc_o

MODEL

class Musicstyle
  include Mongoid::Document
 field :title, type: String
  recursively_embeds_many
end

CONTROLLER

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

VIEW

   <% if @all_musicstyles %>
        <div class="field">
            <%= f.label :parent_musicstyle %>
            <%= f.collection_select( :parent_musicstyle, @all_musicstyles, :_id, :title) %>
        </div>
   <% end %>

Results:

- House
-- Ibiza House
- Ibiza House
-- Child Progressive House
- Progressive House
于 2012-07-04T14:35:34.330 回答