表創建行與2人

Question

的產品型號：

class Usdzar < ActiveRecord::Base 
    has_many :smoothings 
    has_many :smoothvals, through: :smoothings 
end 

class Smoothval < ActiveRecord::Base 
    has_many :smoothprices 
    has_many :usdzars, through: :smoothings 
end 

class Smoothing < ActiveRecord::Base 

    belongs_to :usdzar 
    belongs_to :smoothval 

    accepts_nested_attributes_for :smoothval 
    accepts_nested_attributes_for :usdzar 

    before_save :create_smoothings 

    def create_smoothings 
    smoothval = Smoothval.find(smoothval_id) 
    1.upto(Usdzar.count) do 
     Smoothing.create!(
     usdzar_id => usdzar.id, 
     smoothval_id => smoothval.id, 
     smprice => 99 
     ) 
    end 
end 

使用的光滑控制器我從視圖操作設置smoothval從該表中的項的值，然後希望在執行計算價格在usdzar表中的每一行。我想要插入到平滑表中的輸出。每個價格ID都應該以fval和sval計算的smprice id結束。

我的方法是一個測試只是爲了讓循環工作，但它是失敗的。

遷移：

class CreateSmoothings < ActiveRecord::Migration 
    def change 
    create_table :smoothings do |t| 
     t.decimal :smprice, :precision => 8, :scale => 5 
     t.references :usdzar, index: true, foreign_key: true 
     t.references :smoothval, index: true, foreign_key: true 

     t.timestamps null: false 
    end 
    add_index :smoothings, :smprice 
    end 
end 

class CreateSmoothvals < ActiveRecord::Migration 
    def change 
    create_table :smoothvals do |t| 
     t.decimal :fval, :precision => 2, :scale => 0 
     t.decimal :sval, :precision => 2, :scale => 0 
     t.string :name 
     t.string :nickname 

     t.timestamps null: false 
    end 
    add_index :smoothvals, :name 
    end 
end 

class CreateUsdzars < ActiveRecord::Migration 
    def change 
    create_table :usdzars do |t| 
     t.date :day 
     t.decimal :price, :precision => 8, :scale => 5 
     t.decimal :delta, :precision => 8, :scale => 5 

     t.timestamps null: false 
    end 
    add_index :usdzars, :day 
    add_index :usdzars, :price 
    end 
end 

'本地主機：3000 /的光滑/新'（我選擇smoothval被用來從DD列表進行計算：

<%= form_for(@smoothing) do |f| %> 
    <% if @smoothing.errors.any? %> 
    <div id="error_explanation"> 
     <h2><%= pluralize(@smoothing.errors.count, "error") %> prohibited this smoothing from being saved:</h2> 
     <ul> 
     <% @smoothing.errors.full_messages.each do |message| %> 
     <li><%= message %></li> 
     <% end %> 
     </ul> 
    </div> 
    <% end %> 

    <div class="field"> 
    <%= f.label :smoothvals %><br> 
    <%= f.collection_select :smoothval_id, Smoothval.all, :id, :name %> 
    </div> 
    <div class="actions"> 
    <%= f.submit %> 
    </div> 
<% end %> 

提交當我得到：

undefined method `id' for nil:NilClass 

     Smoothing.create!(
     usdzar_id => usdzar.id, 
     smoothval_id => smoothval.id, 
     smprice => 99 
    ) 

我有很強的PARAMS：

params.require(:smoothing).permit(:smprice, :usdzar_id, :smoothval_id, :usdzars_attributes => [:id, :price, :delta]) 

有人可以給我一個想法，爲什麼它這樣做，以及更好的方法可能是什麼？

Answer 1

在您的create_smoothings方法中，變量usdzar未定義。問題是在你的高達循環，你的方法改成這樣：

def create_smoothings 
smoothval = Smoothval.find(smoothval_id) 
Usdzar.all.each do |usdzar| 
    Smoothing.create!(
    usdzar_id => usdzar.id, 
    smoothval_id => smoothval.id, 
    smprice => 99 
    ) 
end 

Answer 2

我使用控制器的解決方案：我將其移動到模型，但得到它的工作，現在

＃POST /的光滑 DEF創建

@sv = Smoothval.find(smoothing_params[:smoothval_id]) 

Usdzar.all.each do |usdzar| 
    Smoothing.create!(
    usdzar_id: usdzar.id, 
    smoothval_id: @sv.id, 
    smprice: 99 
    ) 
end 
redirect_to smoothings_url, notice: 'Smoothings successfully created.' 

端

不使用嵌套attributes_for

Answer 3

完成在控制器

＃POST /的光滑 DEF創建

sv = Smoothval.find(smoothing_params[:smoothval_id]) 
fval = sv.fval 
sval = sv.sval 



Usdzar.all.each do |usdzar| 

    if usdzar.id == 1 
     prevusdzar = usdzar.price 
     prevfirstsmprice = usdzar.price 
    else 
     previd = (usdzar.id) - 1 
     prevusdzar = Usdzar.find(previd).price 
     prevfirstsmprice = Smoothing.find(previd).firstsmprice 
    end 

    firstsmprice = (((fval * usdzar.delta)/100) + prevusdzar) 

    firstsmdelta = firstsmprice - prevfirstsmprice 

    finalsmprice = (((sval * firstsmdelta)/100) + prevfirstsmprice) 

    Smoothing.create!(
     usdzar_id: usdzar.id, 
     smoothval_id: sv.id, 
     firstsmprice: firstsmprice, 
     firstsmdelta: firstsmdelta, 
     finalsmprice: finalsmprice 
    ) 
end 


redirect_to smoothings_url, notice: 'Smoothings successfully created.' 

末

如果我將它添加到保存之前，我會用什麼動作模式？ 我沒有完成計算，所以它變得相當長，很可能需要一些評論。