has_many:通过可以构建多个实例的nested_form

Question

我的模型中有以下代码:

Class Farm < ActiveRecord::Base
  has_many :farm_products, :dependent => :destroy
  has_many :products, :through => :farm_products
  accepts_nested_attributes_for :farm_products
end

class Product < ActiveRecord::Base
  has_many :farm_products, :dependent => :destroy
  has_many :farms, :through => :farm_products
end

class FarmProduct < ActiveRecord::Base
  belongs_to :farm
  belongs_to :product
end

我有一个表单来创建一个新的Farm,我想创建farm_products以及这个表单.我的farm_products表不仅包含外键字段.如何通过Javascript和/或JQuery添加或删除嵌套列？

UPD.我通过nested_forms找到了一个很棒的宝石,它正是我想做的!这是我视图中的代码

= nested_form_for @farm, :html => { :multipart => true } do |f|
  = f.fields_for :farm_products do |fp|
-#fields goes here
     = fp.link_to_remove 'Remove this task'
     = fp.link_to_add "Add a task", :farm_products

但是有一个错误说

undefined method `klass' for nil:NilClass

我的人际关系可能有问题,但我找不到问题.

Answer 1

的link_to_add需要是外部fields_for块,称为上f对象不是上fp对象.