Question

我认为我有以下内容。我正在试图弄清楚为什么这会让你感到高兴：

<% unless @question.answers.empty? %>
  <% @question.answers.each do |answer| %>
    <%= render :partial => '/answers/answer', :locals => { :question => @question, :answer => answer } %>
  <% end %>
<% end %>

问题：@question.answers.empty?返回false时应为true。它有一些空answer个对象，@question.answers.length返回1而不是0

示例：[#<Answer id: nil, body: nil, user_id: nil, created_at: nil, updated_at: nil, question_id: 18>]

然而，更令人困惑的是，当我在控制台中这样做时，@ question.answers.empty？返回true，长度为0，应该是。为什么会这样？

1.9.3-p327 :001 > question = Question.find(18)
  Question Load (12.2ms)  SELECT "questions".* FROM "questions" WHERE "questions"."id" = $1 LIMIT 1  [["id", 18]]
 => #<Question id: 18, body: "sddd", user_id: 7, created_at: "2013-01-25 01:47:06", updated_at: "2013-01-25 01:47:06"> 
1.9.3-p327 :002 > question.answers.length
  Answer Load (0.7ms)  SELECT "answers".* FROM "answers" WHERE "answers"."question_id" = 18
 => 0 
1.9.3-p327 :003 > question.answers
 => []

此外，特定问题的长度在索引页面上显示0，在显示页面上显示1。

Answer 1

你可能在控制器中有一些东西：

@answer = @question.answers.build

这是为新答案创建一个对象并将其添加到@question.answers对象。您可能希望尝试使用.new而不是.build，这样就不会在@question.answers中将其包含在本地。见Build vs new in Rails 3

与数组对象的混淆

1 个答案: