ElasticSearch 结果上的 Active Record Outer Left Join (Rails 4.2)答案

【问题标题】：Active Record Outer Left Join on ElasticSearch Results (Rails 4.2)ElasticSearch 结果上的 Active Record Outer Left Join (Rails 4.2)
【发布时间】：2015-10-27 07:29:07
【问题描述】：

我在模型上使用了一个范围，它执行左外连接来整合 SQL 查询。我想使用 ElasticSearch 来查询这个模型，但我不知道如何让连接与 ES 配合得很好。

当我尝试将其添加为范围或手动将联接添加到 ES 搜索结果时，我收到此错误：

ActiveRecord::StatementInvalid at /families/search
PG::SyntaxError: ERROR:  syntax error at or near "AS"
LINE 1: ...NT(families.*, COALESCE(SUM(donations.amount), 0) AS total_r...
                                                         ^
: SELECT  COUNT(families.*, COALESCE(SUM(donations.amount), 0) AS total_raised) AS count_families_all_coalesce_sum_donations_amount_0_as_total_rai, families.id AS families_id FROM "families" LEFT OUTER JOIN donations ON families.id = donations.recipient_id WHERE "families"."id" = 56 GROUP BY families.id LIMIT 30 OFFSET 0

这是我的模型：

# app/models/family.rb

require 'elasticsearch/model'
require 'file_size_validator'

class Family < ActiveRecord::Base
  include Elasticsearch::Model
  include Elasticsearch::Model::Callbacks

  has_many :donations, as: :recipient, dependent: :destroy

  scope :approved, -> { where(approved: true).order('families.created_at DESC') }
  scope :unapproved, -> { where approved: false }

  scope :visible, -> { where(visible: true).order('families.created_at DESC') }
  scope :hidden, -> { where(visible: false) }

  scope :include_total_raised, -> { joins('LEFT OUTER JOIN donations ON families.id = donations.recipient_id').select('families.*, COALESCE(SUM(donations.amount), 0) AS total_raised').group('families.id') }

这是我正在搜索的控制器：

class FamiliesController < ApplicationController
  before_action :set_family, only: [:edit, :show, :update, :approval_letter]

  load_and_authorize_resource
  before_action :require_login, only: [:edit, :update, :destroy, :approval_letter]

  def index
    @families = Family.approved.visible.include_total_raised.select(:id, :photo, :first_name, :last_name, :country, :slug).order('families.created_at DESC').page(params[:page]).per(30)
  end

  def search
    if params[:q].present?
      @families = Family.approved.visible.search(params[:q]).records.include_total_raised.page(params[:page]).per(30)
      render :index
    else
      redirect_to families_path
    end
  end

如果您需要任何其他信息，请告诉我。

【问题讨论】：

标签： ruby-on-rails postgresql join activerecord elasticsearch

【解决方案1】：

这最终成为我的 HAML 模板的问题：

%h2= pluralize(@families.length, 'Adopting family')

该行正在尝试count @families ivar，这导致了 Kaminari 和连接的一些问题。当我注释掉该行时，它运行良好，但我仍然想显示找到了多少搜索结果。所以我只是将count 更改为length，效果很好。

【讨论】：