0

我对此有一个展示视图：

<%= @application.application_name %>
<%= @application.application_field %>

它产生了这个：

Application name: New Employment App [#<ApplicationField id: 1, application_id: 1, applicant_id: nil, field_name: "Previous Job", field_type: "String", created_at: "2012-12-03 04:26:06", updated_at: "2012-12-03 04:26:06">, #<ApplicationField id: 2, application_id: 1, applicant_id: nil, field_name: "Previous Address", field_type: "String", created_at: "2012-12-03 04:26:06", updated_at: "2012-12-03 04:26:06">]

但如果我这样做：

<%= @application.application_name %>
<%= @application.application_field.field_name %>

我得到错误：

undefined method `field_name' for #<ActiveRecord::Relation:0x007ff4ec822268>

为什么我会收到此错误？

型号如下

class Application < ActiveRecord::Base
    belongs_to :company
    #has_many :applicants, :through => :application_field
    has_many :application_field
    accepts_nested_attributes_for :application_field, :allow_destroy => true
    attr_accessible :application_name, :application_field_attributes
end

class ApplicationField < ActiveRecord::Base
    belongs_to :application
    has_many :application_fields_value
    #belongs_to :applicant
    attr_accessible :field_name, :field_type, :field_value, :application_field_values_attributes
    accepts_nested_attributes_for :application_fields_value, :allow_destroy => true
end

控制器的显示动作：

# GET /applications/1
  # GET /applications/1.json
  def show
    @application = Application.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @application }
    end
  end
4

3 回答 3

1

这里的Application有很多ApplicationField。例如，一个应用程序有 3 个 application_field。如果您放置 application.application_field 它将收集所有 3 application_field 记录并保存在一个数组中。因此，如果您输入@application.application_field.field_name，它将为数组抛出未定义的方法“field_name”。

      try with <%= @application.application_field[0].field_name %>
于 2012-12-03T05:20:52.080 回答
1 
@application.application_field.first.field_name

...应该让你得到实际的对象。

于 2012-12-03T05:22:14.277 回答
1

您可以按如下方式编写模型：
class Application < ActiveRecord::Base
   belongs_to :company

  has_many :application_fields
  accepts_nested_attributes_for :application_fields, :allow_destroy => true
  attr_accessible :application_name, :application_fields_attributes
end`

现在Application对象显然会有application_fields的集合。

现在您可以在显示页面中显示如下：

<%= @application.application_name %>
<%= @application.application_fields.map{|af| .field_name}.join(',') %>

于 2012-12-03T06:01:30.457 回答