Question

我跟随Railscasts第111集（高级搜索），它在后端工作，但我无法弄清楚我在显示搜索结果时出错了什么

<% @search.listings.each do |listing| %>
<%= render partial: "categories/listing-s" %>
<% end %>

我不会把所有代码都放在她身上，因为它很简单。我有清单模型，显示清单的类别模型和搜索操作的搜索模型。搜索表单位于每个类别的侧栏中

假设我想过滤价格在2000到2400之间的商品。

Started POST "/searches" for 127.0.0.1 at 2016-10-20 21:08:16 +0300
Processing by SearchesController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"ZoKN3mhgmk8ejJE8OKKo+yS7X1R5d7LRzGa9YaIuDVoahH0Fq8iMwclSMVZIej9YwI9i3/8ji+g65A8XRTVhtQ==", "search"=>{"keywords"=>"", "category_id"=>"", "min_price"=>"2000", "max_price"=>"2400"}, "button"=>""}
   (0.2ms)  BEGIN
  SQL (0.5ms)  INSERT INTO "searches" ("keywords", "min_price", "max_price", "created_at", "updated_at") VALUES ($1, $2, $3, $4, $5) RETURNING "id"  [["keywords", ""], ["min_price", #<BigDecimal:7fbab61ebc98,'0.2E4',9(18)>], ["max_price", #<BigDecimal:7fbab61ebba8,'0.24E4',9(18)>], ["created_at", 2016-10-20 18:08:16 UTC], ["updated_at", 2016-10-20 18:08:16 UTC]]
   (2.3ms)  COMMIT
Redirected to http://localhost:3000/searches/15
Completed 302 Found in 7ms (ActiveRecord: 3.0ms)

好的，它已经创建并且对我来说很好看。然后我有

Started GET "/searches/15" for 127.0.0.1 at 2016-10-20 21:08:16 +0300
Processing by SearchesController#show as HTML
  Parameters: {"id"=>"15"}
  Search Load (1.1ms)  SELECT  "searches".* FROM "searches" WHERE "searches"."id" = $1 LIMIT $2  [["id", 15], ["LIMIT", 1]]
  Rendering searches/show.html.erb within layouts/application

  .....

  Listing Load (0.6ms)  SELECT "listings".* FROM "listings" WHERE (price >= '2000.0') AND (price <= '2400.0') ORDER BY created_at DESC
#<Listing:0x007fbab6bea6e0>
#<Listing:0x007fbab6bea500>
#<Listing:0x007fbab6bea3c0>
#<Listing:0x007fbab6bea190>
  Rendered searches/show.html.erb within layouts/application (81.0ms)

日志的最后一部分返回和清单模型的集合，这很棒。为什么我仍然看到未定义的方法`每个＆＃39; for nil：NilClass on＆lt;％@ search.listings.each do | listing | ％GT; ？

使用searhes_controller中的show动作进行更新

def show
    @search = Search.find(params[:id])
end

MODEL

class Search < ApplicationRecord
    def listings
        @listings ||= find_listings
    end

    private

    def find_listings
        listings = Listing.order('created_at DESC')
        listings = listings.where("name like ?", "%#{keywords}%") if keywords.present?
        listings = listings.where(subcategory_id: category_id) if category_id.present?
        listings = listings.where("price >= ?", min_price.to_s) if min_price.present?
        listings = listings.where("price <= ?", max_price.to_s) if max_price.present?
        listings
        puts listings
    end


end

**更新2 **

在社区的帮助下，我发现我不应该在模型中使用puts ，因为它返回nil。希望它能帮助您，以防您遇到类似的问题

Answer 1

Try removing puts listing from the last line, as puts returns nil. so your find_listings method is returning nil instead of actual listings.

未定义的方法`每个＆＃39;为零：NilClass，同时收藏

1 个答案: