Question

我有以下型号：

用户

class User < ActiveRecord::Base
  ...
  attr_accessible :email

  has_many :ingredients, class_name: "Ingredient", foreign_key: "created_by"
end

成分</ P>

class Ingredient < ActiveRecord::Base
 ...
 attr_accessible :created_by
  belongs_to :user
end

我创建了一个成分，并且填充了created_by字段。如果我这样做：

> u = User.find(1)
> u.ingredients.size
=> 1

所以关系正在发挥作用！但如果我这样做：

Ingrendient.last.created_by.email

我收到以下错误：

1.9.3-p362 :012 > Ingredient.last.created_by.email
Ingredient Load (0.3ms)  SELECT "ingredients".* FROM "ingredients" ORDER BY "ingredients"."id" DESC    LIMIT 1
NoMethodError: undefined method `email' for 1:Fixnum
from (irb):12
from /Users/andreucasadella/.rvm/gems/ruby-1.9.3-p362/gems/railties-3.2.11/lib/rails/commands/console.rb:47:in `start'
from /Users/andreucasadella/.rvm/gems/ruby-1.9.3-p362/gems/railties-3.2.11/lib/rails/commands/console.rb:8:in `start'
from /Users/andreucasadella/.rvm/gems/ruby-1.9.3-p362/gems/railties-3.2.11/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'

为什么？

Answer 1

应该是：

class Ingredient < ActiveRecord::Base
 # ...
 belongs_to :user, foreign_key: :created_by
end

class User < ActiveRecord::Base

  has_many :ingredients, foreign_key: :created_by
end

另外，从created_by表中移除users并添加到ingredients。我假设您要将Ingredient与User相关联，这是合理的，因此Ingredient需要created_by个外键。

请注意，我已放弃attr_accessible。对于Rails 4.0+ strong parameters被使用（除非您使用Rails＆lt; 4）。

Rails Custom foreign_key给出了NoMethodError

1 个答案: