ruby-on-rails - Mongoid rails 4 访问关系 embeds_one

Question

我正在使用 Rails 4.0.0, gem 'mongoid', '~> 4', :github=>"mongoid/mongoid", Ruby 2.0.0p247

我有以下型号：

class Policy
  include Mongoid::Document
  field :policy_number, type: String
  field :user_id, type: Integer

  belongs_to :user
  embeds_many :employees    
end

class Employee
  include Mongoid::Document
  field :first_name, type: String
  field :last_name, type: String

  embedded_in :policy
  embeds_one :partner
end

class Partner
  include Mongoid::Document
  field :first_name, type: String
  field :last_name, type: String

  embedded_in :employees#, :inverse_of => :partner
end

在我的控制器中：

def show
@user = User.find(current_user.id)
@policy = @user.policies.first

在我的政策/show.html.erb

  <% @policy.employees.each do |emp| %>
  <%= emp.first_name %>

  <%= emp.partner.first_name  %>

  <% end %>

在 MongoDB 中：

/* 0 */
{
"_id" : ObjectId("52763eb6612d48113c000000"),
"employees" : [ 
    {
        "_id" : ObjectId("5276574e612d4815ca000000"),
        "dob" : null,
        "first_name" : "Jon",
        "last_name" : "Jonson",
        "partner" : {
            "_id" : ObjectId("527737ca612d487238050000"),
            "first_name" : "Bob",
            "last_name" : "Bobbit",
        },
    }
],
"policy_number" : "RF087-2423525",  
"user_id" : ObjectId("52761fce612d487b2c000000")
}

emp.first_name 按预期显示，但 emp.partner.first_name 错误，未定义方法 `first_name' for nil:NilClass

Answer 1

激活身份映射将激活急切加载并解决您的问题。您可以更新您mongoid.yml的：

identity_map_enabled: true