Ruby 索引页面即使为 nil 也显示，当前出现未定义错误

Question

您好，我正在尝试获取属性的索引页以显示当前属性中的租户。

我已通过执行以下

在我的 show.html 页面上运行它

    .wrapper_with_padding
      #house.show
        %h1= @house.title
        %p= number_to_currency(@house.price, :unit => "£")
        %p= simple_format(@house.description)
        Occupied: #{@house.occupied}
        %br/
        -if @house.tenant.present?
          Tenant: #{@house.tenant.first_name} #{@house.tenant.last_name}
        -else
          %p= 'No Tenant Assigned'

我如何为我的索引页采用同样的方法，这就是我目前所拥有的，但我收到错误 'tenant' 未定义。

.wrapper_with_padding
  #houses.clearfix
    - unless @houses.blank?
      - @houses.each do |house|
        %a{ href: (url_for [house])}
          .house
            %p.title= house.title
            %p.postcode= 'Postcode: ' + (house.postcode)
            %p.price= number_to_currency(house.price, :unit => "£") + ' per month'
            -if @house.tenant.present?
              %p.tenant_id= @house.tenant.first_name
            -else
              %p No Tenant Assigned
    - else
      %h2 Add a Property
      %p It appears you have not added any property's

    %button= link_to "New Property", new_house_path

这是完整的堆栈跟踪

Showing C:/Sites/landlord2/app/views/houses/index.html.haml where line #10 raised:

undefined method `tenant' for nil:NilClass
Rails.root: C:/Sites/landlord2

Application Trace | Framework Trace | Full Trace
app/views/houses/index.html.haml:10:in `block in _app_views_houses_index_html_haml__260246869_75400416'
app/views/houses/index.html.haml:4:in `_app_views_houses_index_html_haml__260246869_75400416'

Answer 1

这应该有效：

.wrapper_with_padding
  #houses.clearfix
    - unless @houses.blank?
      - @houses.each do |house|
        %a{ href: (url_for [house])}
          .house
            %p.title= house.title
            %p.postcode= 'Postcode: ' + (house.postcode)
            %p.price= number_to_currency(house.price, :unit => "£") + ' per month'
            -if house.tenant.present?
              %p.tenant_id= house.tenant.first_name
            -else
              %p No Tenant Assigned
    - else
      %h2 Add a Property
      %p It appears you have not added any property's

    %button= link_to "New Property", new_house_path

请注意，虽然我没有修复任何其他错误，但您可能应该阅读一些关于 Haml 规范的内容。

您不必执行 %p= 'No Tenant Assigned'，因为 %p No Tenant Assigned 有效。

Ruby 索引页面即使为 nil 也显示，当前出现未定义错误

Ruby index page display even if nil, currently get undefined error

ruby

ruby-on-rails-4