rails：HABTM和ActiveRecord错误（PG :: UndefinedTable：错误：缺少FROM ...）

因此，我有以下两种模型：

class City < ActiveRecord::Base
  has_and_belongs_to_many :companies
end

class Company < ActiveRecord::Base
  has_and_belongs_to_many :cities
end

联接表迁移为：

class CreateJoinCityCompany < ActiveRecord::Migration    
  def up                                
    create_table :cities_companies do |t|                        
      t.integer :city_id                                                                    
      t.integer :company_id                                                                 
    end                                                                                     
  end                                                                                       

  def down                                                                                  
    drop_table :cities_companies                                                            
  end                                                                                       
end

我正在尝试根据城市ID查找公司：

class CompaniesController < ApplicationController
  def index
      @companies = Company.includes(:cities).where('city.id' => params[:city_id]).references(:cities)
      render :text => @companies.inspect
  end
end

我得到的是：

PG :: UndefinedTable：错误：缺少表“ city”第1行的FROM子句条目：... cities“。” id“ =” cities_companies“。” city_id“在” city“。” id ... ^：SELECT “ company”。“ id” AS t0_r0，“ companies”。“名称” AS t0_r1，“ companies”。“ category_id” AS t0_r2，“ companies”。“ url” AS t0_r3，“ companies”。“ created_at” AS t0_r4， “公司”。“ updated_at” AS t0_r5，“公司”。“ image_file_name” AS t0_r6，“公司”。“ image_content_type” AS t0_r7，“公司”。“ image_file_size” AS t0_r8，“公司”。 “ cities”。“ id” AS t1_r0，“ cities”。“ name” AS t1_r1，“ cities”。“ state_id” AS t1_r2，“城市”。“ created_at” AS t1_r3，“城市”。“ updated_at” AS t1_r4从“ companies”左外联接“ cities_companies”在“ cities_companies”上。“ company_id” =“ companies “。” id“左外联接” cities“在” cities“上。” id“ =” cities_companies“。” city_id“在” city“。” id“ ='14'城市“。” id“ =”城市_公司“。” city_id“其中”城市“。” id“ ='14'城市“。” id“ =”城市_公司“。” city_id“其中”城市“。” id“ ='14'

我尝试了一些事情，例如将参数强制转换为int，但是我需要一些帮助来弄清楚这里发生了什么。