ruby-on-rails - collection_select，未定义的方法 `map' 为 nil :NilClass

Question

我在 @user = User.new 中添加了行以确保它不是零。哪个对象为零？

undefined method `map' for nil:NilClass

Extracted source (around line #11):

8:  <%= f.hidden_field(:width)%>
9:  <%= f.hidden_field(:height)%>
10:     <% @user = User.new %>
11:     <%= collection_select(@user, :full_name, @user_array, :id, {:prompt => 'true'}, {:class=>'select'})%>
12:     <div class="submit-button">
13:         <%= submit_tag("Tag the person!")%>
14:     </div>

Answer 1

@user_array是 nil .确保它设置了一组用户以避免出现此错误消息。

或者，设置 @user_array至 [] (一个空数组)如果你不想在`select 中显示任何选项，例如:

collection_select @user, :full_name, @user_array || [], :id, 
  { prompt: 'true' }, { class: 'select' }