欄目嵌套屬性has_many到

Question

我有三個模型。父母，孩子，類型和關係。關係是引用Parent，Child和Type的豐富連接模型。

問題是，當創建子對象並創建關係表時，關係表中的parent_id未填充。只有孩子和類型是自動填充的。

parent.rb

attr_acccessible :relationships_attributes 

has_many :relationships 
has_many :children, :through => :relationships 
has_many :types, :through => :relationships 

child.rb

attr_acccessible :relationships_attributes 

has_many :relationships 
has_many :parents, :through => :relationships 
has_many :types, :through => :relationships 

accepts_nested_attributes_for :relationships 

relationship.rb

attr_accessible :parent_id, :child_id, :type_id 
belongs_to :parent 
belongs_to :child 
belongs_to :type 

children.controller

def new 
@child = Child.new 
@child.relationships.build 
end 

def create 
@child = Child.new(params[:child]) 
if @child.save 
    redirect_to current_user 
else 
    render "new" 
end 
end 

new.html.erb

<%= simple_form_for @child do |f| %> 
    <%= f.input :first_name, :label => 'First Name' %> 
    <%= f.input :gender, :as => :select, :collection => ['Male', 'Female'] %> 
    <%= f.association :relation_types, :as => :collection_select %> 


    <%= f.button :submit, :class => "primary" %> 

<% end %> 

請幫忙。

謝謝！

Answer 1

似乎忘記很多事情：

@child.relationships.build 

應該

@child.relationships.build :parent_id => ... 

，並鑑於 代替

f.association :relation_types, :as => :collection_select 

使用

f.field_for :relationships do |g| 
    g.association :types, :as => :collection_select 
    g.hidden :parent_id #need to save this