包含和位置不检索正确关联的对象

Question

我试图在我的项目上实现搜索功能，所以我添加了类方法：

    class Donation < ActiveRecord::Base
      belongs_to :member
      def self.search_by_name name
        includes(:member).where(member:  { name: name } )
      end
    end

我在donatinos#index里叫它

    class DonationsController < ApplicationController
      def index
        search_donations
      end

      private
      def search_donations
        if !params[:name].blank?
          @donations = Donation.search_by_name params[:name]
        else
          @donations = Donation.all
        end
      end    
    end

最后，我实现了索引模板：

    <%= form_tag donations_path,:method => 'get' do %>
        <%= text_field_tag :name %>
        <%= submit_tag "search", name: nil %>
    <% end %>
    <table>
        <% @donations.each do |donation| %>
        <tr>
            <td><%= donation.total %></td>
        </tr>
        <% end %>
        </tbody>
    </table>

我得到了错误信息后，我采取了“泰德王”的形式。

    SQLite3::SQLException: no such column: member.name: SELECT "donations"."id" AS t0_r0, "donations"."organization_id" AS t0_r1, "donations"."category" AS t0_r2, "donations"."borrow_id" AS t0_r3, "donations"."member_id" AS t0_r4, "donations"."total" AS t0_r5, "donations"."note" AS t0_r6, "donations"."created_at" AS t0_r7, "donations"."updated_at" AS t0_r8, "donations"."time" AS t0_r9, "members"."id" AS t1_r0, "members"."no" AS t1_r1, "members"."name" AS t1_r2, "members"."nick_name" AS t1_r3, "members"."introducer" AS t1_r4, "members"."role" AS t1_r5, "members"."gender" AS t1_r6, "members"."birthday" AS t1_r7, "members"."lunar_birthday" AS t1_r8, "members"."lunar_deathday" AS t1_r9, "members"."identified_number" AS t1_r10, "members"."home_phone" AS t1_r11, "members"."company_phone" AS t1_r12, "members"."bbcall" AS t1_r13, "members"."mobile" AS t1_r14, "members"."address" AS t1_r15, "members"."permanent_address" AS t1_r16, "members"."education" AS t1_r17, "members"."job" AS t1_r18, "members"."created_at" AS t1_r19, "members"."updated_at" AS t1_r20, "members"."organization_type" AS t1_r21, "members"."organization_id" AS t1_r22, "members"."involved" AS t1_r23 FROM "donations" LEFT OUTER JOIN "members" ON "members"."id" = "donations"."member_id" WHERE "member"."name" = 'Ted Wang'

我用错了includes吗？成员有属性名，我也运行db:migrate。

Answer 1

按照Rails的惯例，表名是小写和多元的模型名称，因此在where子句中，您应该指定members (复数)，而不是member (单数)。

您可以很容易地调试这个错误消息：SQLite3::SQLException: no such column: member.name。有了错误消息，就可以诊断表名是members，所以查询中的某些内容肯定是错误的，因为它引用的是member.name而不是members.name。

def self.search_by_name name
  includes(:member).where(members: { name: name } )
  ##                       ^
  ##                       plural
end

Answer 2

 def self.search_by_name name
    includes(:member).where("members.name = ?", name)
 end

其他一切都保持不变。

Answer 3

您可以使用范围(这通常是通过rails中的方法指定查询的标准方法)。

scope :filter_by_member_name, lambda { |name| select("*").where("donations d, members m").where("d.member_id= m.id").where("m.name LIKE ?",  "%#{value}%") if name }

然后在你的控制器

@donations = Donation.filter_by_member_name(params[:name])

通过手动加入会员和捐款，您不需要使用活动记录来触发两个查询并将所有内容拼凑在一起。

只需替换select()中的参数即可。