Rails 显示每个 id 产品的最大出价

Question

我试图在每个产品旁边的索引视图页面中打印出该产品的最高出价。所以索引视图中的结果应该是这样的：

香蕉（香蕉的最大量）
Table（table 的最大金额）
等等

我知道如何打印出所有产品总和的最大值，但不知道每个产品的最大数量。话虽如此，我附上了我的代码：

路线：

Rails.application.routes.draw do
  # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html

  get "/new", to: "users#new"
  # get "/index", to: "products#index"
  get "/products", to: "products#index", as: :products

  get "/new_products", to: "products#new"
  #  el form_for siempre necesitará un path en forma de as: ... ya que no le sirve solo la url
  post "/products", to: "products#create"
  get "/products/show/:id", to: "products#show", as: :product
  post "/bids/new_bid", to: "bids#create"
  # post "/new_bid", to: "bids#create"
  post "/products", to: "bids#pass_bid_amount"

end

出价控制器：

class BidsController < ApplicationController
  
  def create
    user= User.find_by(email: params[:email])
    if Time.now < params[:product_deadline]
      @bid= Bid.new(amount: params[:amount].to_i, user_id: user.id.to_i, product_id: params[:product_id].to_i)    
      if @bid.save
        redirect_to product_path(@bid.product_id)
      else
        render plain: "something went wrong"
      end
    else
      render plain:" Too late"
    end 
  end

  def pass_bid_amount
    @bid= Bid.new(amount: params[:amount].to_i, user_id: user.id.to_i, product_id: params[:product_id].to_i)
    @bid.save
    render "index"
    # redirect_to products_path(@bid.product_id)  
  end

end

INDEX.HTML.ERB:

<% @products.each do |product| %>
  <p><%= link_to product.title, product_path(product.id) %></p>
  <p><% %></p> 
<% end %>  

<p><%=  Bid.maximum(:amount) %> </p>

This maximum amount is not of every single object but the total of all products

<p><%= @products.inspect %></p>
<p><%= Bid.new.inspect %></p>
<!-- <p><%= @bid.inspect %></p> -->

我在浏览器中看到的是：

banana

table

tree

99999999

This maximum amount is not of every single object but the total of all objects

#<ActiveRecord::Relation [#<Product id: 1, title: "banana", description: "this is a fruit", user_id: nil, deadline: "2016-11-22 00:00:00", created_at: "2016-11-12 12:40:01", updated_at: "2016-11-12 12:40:01">, #<Product id: 2, title: "table", description: "this is an object", user_id: nil, deadline: "2016-11-22 00:00:00", created_at: "2016-11-12 12:40:01", updated_at: "2016-11-12 12:40:01">, #<Product id: 3, title: "tree", description: "this is a tree", user_id: nil, deadline: "2016-11-22 00:00:00", created_at: "2016-11-12 12:40:01", updated_at: "2016-11-12 12:40:01">]>

#<Bid id: nil, amount: nil, user_id: nil, product_id: nil, created_at: nil, updated_at: nil>

架构：

ActiveRecord::Schema.define(version: 20161109151534) do

  create_table "bids", force: :cascade do |t|
    t.integer  "amount"
    t.integer  "user_id"
    t.integer  "product_id"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.index ["product_id"], name: "index_bids_on_product_id"
    t.index ["user_id"], name: "index_bids_on_user_id"
  end

  create_table "products", force: :cascade do |t|
    t.string   "title"
    t.string   "description"
    t.integer  "user_id"
    t.datetime "deadline"
    t.datetime "created_at",  null: false
    t.datetime "updated_at",  null: false
    t.index ["user_id"], name: "index_products_on_user_id"
  end

  create_table "users", force: :cascade do |t|
    t.string   "email"
    t.string   "name"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
  end

end

Answer 1

显示您的产品控制器。

或者使用这样的东西：

@products.joins(:bids)
    .where("max_bid = (select max(amount) from bids where product_id = product.id"))

Answer 2

实际上这是 INDEX.HTML.ERB 文件中的正确响应：

<% @products.each do |product| %>




<p><%= link_to product.title, product_path(product.id) %> 
<%  maximum_bid = product.bids.max_by {|bid| bid.amount }  %>
<p><%= maximum_bid.amount%></p>



</p>
<p><% %></p> 
<% end %>  

<!-- <p><%=  Bid.maximum(:amount) %> </p> -->




<p><%= @products.inspect %></p>
<p><%= Bid.new.inspect %></p>
<!-- <p><%= @bid.inspect %></p> -->

现在可以了:)

Rails 显示每个 id 产品的最大出价

Rails show maximum amount of a Bid for every id product

schema

routes

ruby-on-rails

erb