rails nested_forms错误和逻辑

Question

我试图添加一些字段到我的嵌套窗体。我已经包含了宝石nested_forms（https://github.com/ryanb/nested_form）。

对于我的预建地图，它工作正常，但我不能添加新的字段。

我的控制器：

def new 
    @people = Person.all 
    @vehicles = Vehicle.all 
    @roles = Role.all 
    @pratice_people = [] 
    @people.each do |a| 
    if a.at1 == true 
     @pratice_people << a 
    end 
    end 
    @practice = Practice.new 
    @pratice_people.count.times { @practice.uebung_maps.build } 
    render action: "new" 
end 

和我的形式：

<% @runs = 0 %> 
<%= f.fields_for :uebung_maps do |map| %> 
    <tr> 
    <%= map.hidden_field :role_id, :id => "role_id_#{@runs}" %> 
    <%= map.hidden_field :vehicle_id, :id => "vehicle_id_#{@runs}" %> 
    <%= map.hidden_field :person_id , :value => @pratice_people[@runs].id %><br/> 
    <td><%= @pratice_people[@runs].name %></td> 
    <td><%= map.select :role_id, options_from_collection_for_select(@roles, :id, :name), :include_blank => true %></td> 
    <td><%= map.select :vehicle_id, options_from_collection_for_select(@vehicles, :id, :name), :include_blank => true %></td> 
    <td><%= map.text_field :time %></td> 
    </tr> 
    <% @runs += 1 %> 
<% end %> 

<%= f.link_to_add "+" , :uebung_maps %> 

，如果我尝试访问该页面时，我得到以下错误报告

Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id 

我必须（或如何）创建一个逻辑重新运行Practice.uebung_maps.build?，因为我认为这是在nested_forms宝石....

Answer 1

首先，确保模型创建正确。

class Practice < ActiveRecord::Base 
    has_many :uebung_maps 
    accepts_nested_attributes_for :uebung_maps 
end 

class UebungMap < ActiveRecord::Base 

end 

其次，确保form_for正确嵌套

<%= nested_form_for @practice do |f| %> 
    <%= f.fields_for :uebung_maps do |uebung_maps_form| %> 
    <%= uebung_maps_form.text_field :time %> 
    <% end %> 
    <p><%= f.link_to_add "+", :uebung_maps %></p> 
<% end %>