如何添加一個條目到模型的has_many：通過

Question

class Project < ActiveRecord::Base 
    has_many :accounts 
    has_many :sites, through: :accounts 
end 

class Site < ActiveRecord::Base 
    has_many :accounts 
    has_many :projects, through: :accounts 
    accepts_nested_attributes_for :accounts 
end 

class Account < ActiveRecord::Base 
    belongs_to :site 
    belongs_to :project 
end 

p = Project.find(1) 

2.1.4 :011 > p.sites.create({"url"=>"site.ru", "accounts_attributes"=>{"0"=>{"email"=>"mail@site.ru"}}}) 
    (0.3ms) BEGIN 
    SQL (1.8ms) INSERT INTO `sites` (`created_at`, `updated_at`, `url`) VALUES ('2015-09-04 07:09:53', '2015-09-04 07:09:53', 'site.ru') 
    SQL (0.3ms) INSERT INTO `accounts` (`created_at`, `email`, `site_id`, `updated_at`) VALUES ('2015-09-04 07:09:53', 'mail@site.ru', 3, '2015-09-04 07:09:53') 
    SQL (0.3ms) INSERT INTO `accounts` (`created_at`, `project_id`, `site_id`, `updated_at`) VALUES ('2015-09-04 07:09:53', 1, 3, '2015-09-04 07:09:53') 
    (1.2ms) COMMIT 
=> #<Site id: 3, url: "site.ru", created_at: "2015-09-04 07:09:53", updated_at: "2015-09-04 07:09:53"> 

問：

1. 爲什麼添加2記錄？
2. 要在帳戶模型中添加單個項目，並填寫field_id，project_id，email？

Answer 1

第一個帳戶記錄被自動創建，因爲Site通過Account相關Project。

創建第二條記錄是因爲您的Site模型中有accepts_nested_attributes_for :accounts，並且在創建Site記錄時傳遞嵌套屬性。

你能否澄清一下，你想要做什麼？