在我的索引.html.erb 中为 nil：NilClass 获取未定义的方法 'each'

Question

我得到nil的未定义方法' each':NilClass在我的index.html。例如，当我在模型中使用tire实现弹性搜索功能时。可能的原因和解决办法是什么?

index.html.erb:

    <div class="page-header">
  <h1>Friends</h1>
<%= form_tag user_friendships_path, method: :get do %>
      <p>
            <%= text_field_tag :query, params[:query] %>
            <%= submit_tag "Search", name: nil %>
      </p>
<% end %>

</div>
<div>
      <strong>Friend list:</strong>
      <%= link_to 'All', user_friendships_path %> |
      <%= link_to 'Blocked', user_friendships_path(list: 'Blocked') %> |
      <%= link_to 'Requested', user_friendships_path(list: 'Requested') %> |
      <%= link_to 'Accepted', user_friendships_path(list: 'Accepted') %> |
      <%= link_to 'Pending', user_friendships_path(list: 'Pending') %>
</div>
<% @user_friendships.each do |friendship| %>
<% friend = friendship.friend %>
<div id="<%= dom_id(friendship) %>" class="friend row">
      <div class="span1">
            <%= link_to image_tag(friend.gravatar_url), profile_path(friend) %>
      </div>
      <div class="span7">
            <strong><%= friend.full_name %></strong><br />
            <% if friendship.pending? %>
            <em>Friendship is pending.</em> <%= link_to "Delete request", edit_user_friendship_path(id: friend.user_name) %>.
            <% end %>
            <% if friendship.requested? %>
            <em>Friendship requested.</em> <%= link_to "Accept Friendship", edit_user_friendship_path(id: friend.user_name) %>.
            <% end %>
            <% if friendship.accepted? %>
            <em>Friendship started <%= friendship.updated_at %>.</em> <%= link_to "Update friendship", edit_user_friendship_path(id: friend.user_name) %>.
            <% end %>
            <% if current_user.blocked_friends.include?(friend) %>
            <%= form_for friendship, url: user_friendship_path(friendship), method: :delete do |form| %>
                  <%= submit_tag "Unblock", class: 'btn btn-danger' %>
            <% end %>  
            <%end%>
      </div>
</div>
<% end %>

Model(仅需要的代码)-> user_friendship。rb:

    class UserFriendship < ActiveRecord::Base
include Tire::Model::Search
include Tire::Model::Callbacks

  def self.search(params)
     tire.search(load: true) do
       query { string params[:query] } if params[:query].present?
     end
   end
  attr_accessible :user, :friend, :user_id, :friend_id, :state
  belongs_to :user

Controller -> user_friendship_controller.rb

 class UserFriendshipsController < ApplicationController

    before_filter :authenticate_user!
  respond_to :html, :json
    def index

    @user_friendships = current_user.user_friendships.all.search(params)

    case params[:list]
    when nil
      @user_friendships = current_user.pending_user_friendships.all + current_user.accepted_user_friendships.all + current_user.requested_user_friendships.all
    when 'Blocked'
      @user_friendships = current_user.blocked_user_friendships.all
    when 'Pending'
      @user_friendships = current_user.pending_user_friendships.all
    when 'Accepted'
      @user_friendships = current_user.accepted_user_friendships.all
    when 'Requested'
      @user_friendships = current_user.requested_user_friendships.all
    end
    respond_with @user_friendships
  end

Answer 1

如果你让你的搜索方法返回一个空数组[]而不是nil，这应该是好的

它可以看起来像

   def self.search(params)
     tire.search(load: true) do
       query { string params[:query] } if params[:query].present?
     end || []
   end

Answer 2

此错误告诉您在发送每条消息时@user_friendship为nil。据推测，在params[:list] case语句中如何分配@user_friendship存在问题。您需要通过故障排除params[:list] case语句来弄清楚为什么在呈现视图时@user_friendship为nil。我建议调试应用程序或记录params[:list]/@user_friendship的值，以查看正在调用的情况，然后找出被调用的情况导致nil值的原因。好运！