Rails 4具有simple_form_for，has_many和嵌套屬性

Question

我實際上需要與此功能相同的功能：

https://robots.thoughtbot.com/accepts-nested-attributes-for-with-has-many-through

而且我一直在四處尋找（使它正常運行），但一直遇到障礙。 我還是Ruby和Rails的新手，在前進方面需要幫助。 這是我目前的實現：

/models/transfer.rb

class Transfer < ActiveRecord::Base

  validates :name, presence:   true,
                   uniqueness: { case_sensitive: false }

  has_many  :transfer_accounts, inverse_of: :transfer
  has_many  :accounts,          through:    :transfer_accounts

  accepts_nested_attributes_for :transfer_accounts

end


/models/transfer_account.rb

class TransferAccount < ActiveRecord::Base

  validates :account_transfer_role, presence: true

  belongs_to :account,  inverse_of: :transfer_accounts
  belongs_to :transfer, inverse_of: :transfer_accounts

  validates :account,  presence: true
  validates :transfer, presence: true

  accepts_nested_attributes_for :account

end


/models/account.rb

class Account < ActiveRecord::Base

  validates :name,           presence:   true,
                             uniqueness: { case_sensitive: false }
  validates :user_name,      presence:   true
  validates :password,       presence:   true
  validates :account_number, presence:   true,
                             uniqueness: { case_sensitive: false }
  validates :routing_number, presence:   true

  has_many :transfer_accounts, inverse_of: :account
  has_many :transfers,         through:    :transfer_accounts

  belongs_to :bank, inverse_of: :accounts

end


/models/bank.rb

class Bank < ActiveRecord::Base

  validates :name,        presence:   true,
                          uniqueness: { case_sensitive: false }
  validates :connect_uri, presence:   true

  has_many :accounts

end


/controllers/transfers_controller.rb

class TransfersController < ApplicationController

  def new
    @transfer = Transfer.new
    @transfer.transfer_accounts.build(account_transfer_role: 'source').build_account
    @transfer.transfer_accounts.build(account_transfer_role: 'destination').build_account
    @valid_banks = Bank.all.collect {|c| [c.name, c.id]}  # available banks seeded in database
  end

  def index
    @transfers = Transfer.all
  end

  def show
    @transfer = resource
  end

  def create
    @transfer = Transfer.new(transfer_params)
    if @transfer.save
      redirect_to transfers_path, notice: "Transfer Created"
    else
      redirect_to transfers_path, alert:  "Transfer Not Created"
    end
  end

  def edit
    resource
  end

  def update
    if resource.update_attributes(transfer_params)
      redirect_to transfers_path(resource),     notice: "Transfer Updated"
    else
      redirect_to edit_transfer_path(resource), alert:  "Transfer Not Updated"
    end
  end

  def destroy
    resource.destroy
  end


  private

  def resource
    @transfer ||= transfer.find(params[:id])
  end

  def transfer_params
    params.require(:transfer).
      permit(:name, :description,
             transfer_accounts_attributes:
               [:account_transfer_role,
                account_attributes:
                  [:name, :description, :user_name, :password,
                   :routing_number, :account_number
                  ]
               ])
  end

end


/controllers/banks_controller.rb

class BanksController < ApplicationController

  def index
    @bank = Bank.new
    @banks = Bank.by_last_updated_at
  end

  def show
    @bank = resource
  end

  def create
    @bank = Bank.new(bank_params)
    if @bank.save
      redirect_to banks_path, notice: "Bank Created"
    else
      redirect_to banks_path, alert: "Bank Not Created"
    end
  end

  def edit
    resource
  end

  def update
    if resource.update_attributes(bank_params)
      redirect_to banks_path(resource), notice: "Bank Updated"
    else
      redirect_to edit_bank_path(resource), alert: "Bank Not Updated"
    end
  end

  def destroy
    resource.destroy
  end


  private

  def resource
    @bank ||= Bank.find(params[:id])
  end

  def bank_params
    params.require(:bank).
      permit(:name, :description, :connection_uri)
  end

end


/views/transfers/_form.html.haml

= simple_form_for :transfer do |t|
  .form-inputs

    = t.input :name, label: "Transfer Name"
    = t.input :description, required: false, label: "Transfer Description"

    = t.simple_fields_for :transfer_accounts do |ta|

      - role = ta.object.account_transfer_role.titleize

      = ta.input :account_transfer_role, as: :hidden

      = ta.simple_fields_for :account do |a|

        = a.input :bank_id, collection:    @valid_banks,
                            include_blank: 'Select bank...',
                            id:            'bank',
                            class:         'bank_selector',
                            label:         '#{role} Bank',
                            error:         '#{role} bank selection is required.'

        = a.input :name, label: "#{role} Account Name"
        = a.input :description, required: false, label: "#{role} Account Description"
        = a.input :user_name, label: "#{role} Account User Name"
        = a.input :password, label: "#{role} Account Password"
        = a.input :account_number, label: "#{role} Account Number"
        = a.input :routing_number, label: "#{role} Account Routing Number"

  = t.submit


/db/migrate/20151102001000_create_transfers.rb

class CreateTransfers < ActiveRecord::Migration
  def change
    create_table :transfers do |t|

      t.string :name, null: false, default: ''
      t.text   :description

      t.timestamps

    end
  end
end


/db/migrate/20151102002000_create_transfer_accounts.rb

class CreateTransferAccounts < ActiveRecord::Migration
  def change
    create_table :transfer_accounts do |t|

      t.string :account_transfer_role, null: false, default: ''

      t.references :transfer, index: true
      t.references :account,  index: true

      t.timestamps null: false

    end
  end
end


/db/migrate/20151102003000_create_accounts.rb

class CreateAccounts < ActiveRecord::Migration
  def change
    create_table :accounts do |t|

      t.string  :name,           null: false, default: ''
      t.string  :description
      t.string  :user_name,      null: false, default: ''
      t.string  :password,       null: false, default: ''
      t.string  :account_number, null: false, default: ''
      t.string  :routing_number, null: false, default: ''

      t.references :bank, index: true

      t.timestamps

    end
  end
end


/db/migrate/20151102004000_create_banks.rb

class CreateBanks < ActiveRecord::Migration
  def change
    create_table :banks do |t|

      t.string :name,           null: false, default: ''
      t.string :description
      t.string :connection_uri, null: false, default: ''

      t.timestamps

    end
  end
end


/db/migrate/20151102005000_add_foreign_keys_to_transfer_accounts.rb

class AddForeignKeysToTransferAccounts < ActiveRecord::Migration
  def change

    add_foreign_key :transfer_accounts, :accounts
    add_foreign_key :transfer_accounts, :transfers

  end
end


/db/migrate/20151102006000_add_foreign_keys_to_accounts.rb

class AddForeignKeysToAccounts < ActiveRecord::Migration
  def change

    add_foreign_key :accounts, :banks

  end
end


/db/seeds.rb

Bank.create(name:           'Acme Savings and Loan',
            description:    'The number one bank in the northeast',
            connection_uri: 'https://www.acmesavings.com')
Bank.create(name:           'First Bank of Anytown',
            description:    'The first and only bank in Anytown',
            connection_uri: 'https://www.firstbankanytown.com')
Bank.create(name:           'Generibank',
            description:    'The most generic bank in the country',
            connection_uri: 'https://www.generibank.com')


/config/routes.rb

Rails.application.routes.draw do

  resources  :transfers
  resources  :accounts
  resources  :banks
  root to:   'dashboard#index'

end

所以，目前我的問題是：

1. 表單視圖中的這一行- role = ta.object.account_transfer_role.titleize
   給我一個nil：NilClass的“ undefined method`account_transfer_role '錯誤”，那我在做什么錯呢？

2. 為什么transfer_account模型中的accepts_nested_attributes_for行有效（或為什么有效）？ 我的印象是accepts_nested_attributes_for在關聯的belongs_to端不起作用，因為它不是父代（或具有某種作用的）。

3. 如果我注釋掉與問題＃1有關的代碼以避免該錯誤，則會呈現該表單，但我只會得到一組account嵌套屬性的輸入框。 隨着每個transfer有兩個transfer_accounts和兩個accounts建立和與之相關的“ 新 ”行動transfers_controller （與transfer_account :account_transfer_role “ 源 ”和“ 目的地 ”的值），我不應該會得到兩套的account嵌套屬性輸入框？

4. 單數/復數對我的嵌套屬性是否正確？ 從他們的關聯開始，基本上讓他們保持一致。 例如， transfer has_many :transfer_accounts ，因此transfer_accounts在以下所有方面都是復數的：

    /models/transfer.rb accepts_nested_attributes_for :transfer_accounts /controllers/transfers_controller.rb @transfer.transfer_accounts.build(account_transfer_role: 'source').build_account @transfer.transfer_accounts.build(account_transfer_role: 'destination').build_account . . . def transfer_params params.require(:transfer). permit(:name, :description, transfer_accounts_attributes: [:account_transfer_role, account_attributes: [:name, :description, :user_name, :password, :routing_number, :account_number ] ]) end /views/transfers/_form.html.haml = m.simple_fields_for :transfer_accounts do |ma| 

   除奇數外， account也是如此。

5. 如果執行第3步，則使用提供的一組account屬性填寫表單，然后提交，我將收到“ No route match [POST]“ / transfers / new ”錯誤。因此，顯然我的路由有問題。我不確定transfers和accounts應如何顯示在route.rb文件中。

    resources :transfers resources :accounts 

   或作為

    resources :transfers do resources :accounts end 

   還是其他方式 另外，我也不知道route文件中是否也需要transfer_accounts 。

如果您已到達這一行，謝謝您的耐心。：>）並且，您所能提供的任何幫助將不勝感激。

蒂姆，干杯

Answer 1

事實證明，該解決方案非常簡單，可以解決我在問題1、3、4和5中提出的每個問題。

在表單中，我更改了這一行：

= simple_form_for :transfer do |t|

對此：

= simple_form_for @transfer do |t|

對於問題1， account_transfer_role不再為零。
對於問題3，它開始為兩個transfer_accounts渲染輸入框。
如圖所示，對於問題4，強參數中的單數和復數證明是正確的。
對於問題5，此路線的版本證明是正確的：

resources  :transfers
resources  :accounts

盡管我將其簡化為：

resources  :transfers, :accounts

至於問題2，我想出的最佳答案是我的理解似乎不正確，並且accepts_nested_attributes_for:確實在關聯的belongs_to方面起作用，因為它對我belongs_to 。

我希望這對has_many, through關聯為has_many, through具有嵌套屬性的表格而苦苦掙扎的人有所幫助。

干杯!