使用条件过滤器细分在 Ruby on Rails 中显示记录

Question

如果没有发送params[:subject_id]，如何显示表中的所有记录，或者过滤发送params[:subject_id]时将显示的记录？

到目前为止，我在页面控制器中有一个 before 过滤器来检查是否已发送params[:subject_id]并创建一个实例变量。

  private
  def find_subject
    if params[:subject_id]
      @subject = Subject.find_by_id(params[:subject_id])
    else
      @subject = Subject.all
    end
  end

问题出在执行此操作时的操作中@pages仅存储最后一条记录，但不会破坏视图中的任何内容。

  before_filter :find_subject
  def list
    @subject.each do |subject|
      @pages = Page.order("pages.position ASC").where(:subject_id => subject.id)
    end
  end

但是如果我这样做

  def list
      @pages = Page.order("pages.position ASC").where(:subject_id => @subject.id)
  end

根本没有返回任何记录，当我在 Webrick 控制台中检查输出时，我看到这个

Subject Load (0.2ms)  SELECT `subjects`.* FROM `subjects` 
Page Load (0.4ms)  SELECT `pages`.* FROM `pages` WHERE `pages`.`subject_id` = 2186859380 ORDER BY pages.position ASC

我不确定它是如何获得2186859380的id

我也这样累了

  def list
    if @subject.object_id.nil?
      @pages = Page.order("pages.position ASC")
    else
      @pages = Page.order("pages.position ASC").where(:subject_id => @subject.object_id)
    end
  end

然而，这也抛出了一些错误，也打破了我的观点。

这是我的观点，因此您可以获得完整的图片

<div class="page list">
    <h2>Pages</h2>
<%= link_to "Add a new Page", {:action => "new", :subject_id => @subject.id}, :class => "action new" %>
    <table class="listing" summary="Pages List">
        <tr class="header">
            <th>&nbsp;</th>
            <th>Subject</th>
            <th>Page</th>
            <th>Visible</th>
            <th>Sections</th>
            <th>Permalink</th>
            <th>Actions</th>
        </tr>
        <% @pages.each do |page| %>
        <tr class="<%= cycle("odd", "even") %>">
            <td><%= page.position %></td>
            <td><%= page.subject.name %></td>
            <td><%= page.name %></td>
            <td class="center"><%= page.visible ? "Yes" : "No" %></td>
            <td class="center"><%= page.sections.size %></td>
            <td><%= page.permalink %></td>
            <td class="actions">
                <%= link_to("Sections", {:controller => "sections", :action => "list", :page_id => page.id}, :class => "action delete")%>
                <%= link_to("Show", {:action => "show", :id => page.id, :subject_id => @subject.id}, :class => "action show")%>
                <%= link_to("Edit", {:action => "edit", :id => page.id, :subject_id => @subject.id}, :class => "action edit")%>
                <%= link_to("Delete", {:action => "delete", :id => page.id, :subject_id => @subject.id}, :class => "action delete")%>
            </td>
        </tr>
        <% end %>
    </table>
</div>

任何关于我做错的事情的帮助将不胜感激。

Answer 1

我认为你应该像这里这样在主题中添加一个"s"：

  private
  def find_subject
    if params[:subject_id]
      @subject = Subject.find_by_id(params[:subject_id])
    else
      @subjects = Subject.all
    end
  end

所以现在，你可以这样做：

def list
  if subjects
    @subject.each do |subject|
      @pages = Page.order("pages.position ASC").where(:subject_id => subject.id)
    end
  else
    @pages = Page.order("pages.position ASC").where(:subject_id => @subject.id)
  end
end

您可以在您的视图中做类似的事情...