Ruby on rails 通过Rails 3中的关联

我在rails 3中遇到了一些问题。我得到了一个“nil:NilClass”错误的未定义方法“full_name”

查看

<% @comparison.each do |v| %>
<%= link_to v.trial.user.full_name, trial_trials_path %>
<% end %>

控制器

class SearchController < ApplicationController

  def search
   @comparison = Result.where('variety_id' => [params[:variety_one], params[:variety_two]], 'year' => params[:year]).
   joins(:trial).where('trials.irrigated' => params[:irrigated], 'trials.region_id' => params[:regions])
  end

class User < ActiveRecord::Base

  has_many :trials

  def full_name
    "#{first_name} #{last_name}"
  end

end

class SearchController[params[：variation\u one]，params[：variation\u two]，'year'=>params[：year]）。
联接（：trial）.where（'trials.irlivated'=>params[：irlivated]，'trials.region_id'=>params[：regions]）
结束

结果

class Result < ActiveRecord::Base

  belongs_to :trial, :primary_key => 'trial_id'
  has_many :users, :through => :trial

end

类结果'trial\u id'
拥有多个：用户，：至=>：试用版
结束

用户

class SearchController < ApplicationController

  def search
   @comparison = Result.where('variety_id' => [params[:variety_one], params[:variety_two]], 'year' => params[:year]).
   joins(:trial).where('trials.irrigated' => params[:irrigated], 'trials.region_id' => params[:regions])
  end

class User < ActiveRecord::Base

  has_many :trials

  def full_name
    "#{first_name} #{last_name}"
  end

end

class用户

试用版

class Trial < ActiveRecord::Base

  has_many :results
  belongs_to :user, :primary_key => 'user_id'

end

classtrial'user\u id'
结束

当您调用

v.trial.user.full\u name

时-如果Trail没有用户，它将尝试调用nil对象的全名，这将导致您看到的错误

---

尝试进行一些调试，找出对象为零的原因

为基兰干杯。你是对的，有些条目是空的，但是当我执行“除非v.trial.user.full_name.blank”时，我会得到相同的错误。你需要执行除非v.trial.userbrilliant。再次感谢。