Rails 4 表格：has_many 通过：复选框

Question

原题

两个资源：users 和 animals. 创建用户时，客户端选中复选框以说明他们有多少只动物。

提交用户表单时，不仅要新建一条user记录，还要在animal_users rich join table中新建一堆记录到代表客户选择的每个复选框。

我认为问题是我没有为表单中的复选框部分正确指定内容。我查看了 checkbox_tag API, the Rails Guides on Forms，以及许多网站和 Whosebug 帖子。

提前致谢，代码如下：

原码（答案码往下）:

型号：

#models/user.rb
class User < ActiveRecord::Base
  has_many :animals, through: :animal_users
  has_many :animal_users
  accepts_nested_attributes_for :animal_users, allow_destroy: true
end

#models/animal.rb
class Animal < ActiveRecord::Base
  has_many :users, through: :animal_users
  has_many :animal_users
end

#models/animal_user.rb
class AnimalUser < ActiveRecord::Base
  belongs_to :animal
  belongs_to :user
end

user形式：

#views/users/_form.html.erb
    <%= form_for(@user) do |f| %>
  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  </div>

  <div>
    <% Animal.all.each do |animal| %>
    <label>
        <%= check_box_tag "user[animal_ids][]", animal.id, f.object.animals.include?(animal) %>
        <%= animal.animal_name %>
    <% end %>
  </div>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

users_controller.rb

中的强参数

def user_params
      params.require(:user).permit(:name, animal_users_attributes: [:_destroy, :id, :user_id, :animal_id])
end

答案代码在这里:

型号：

#models/user.rb
class User < ActiveRecord::Base
  has_many :animals, through: :animal_users
  has_many :animal_users
end

#models/animal.rb
class Animal < ActiveRecord::Base
  has_many :users, through: :animal_users
  has_many :animal_users
end

#models/animal_user.rb
class AnimalUser < ActiveRecord::Base
  belongs_to :animal
  belongs_to :user
end

user形式：

#views/users/_form.html.erb
<%= form_for(@user) do |f| %>
  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  </div>

  # Checkbox part of the form that now works!
    <div>
      <% Animal.all.each do |animal| %>
        <%= check_box_tag "user[animal_ids][]", animal.id, f.object.animals.include?(animal) %>
        <%= animal.animal_name %>
      <% end %>
    </div>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

users_controller.rb

中的强参数

  def user_params
    params.require(:user).permit(:name, animal_ids: [])
  end

为了完整起见，这是提交表单时传递到服务器的内容：

Parameters: {"utf8"=>"✓", "authenticity_token"=>"xyz=", "user"=>{"name"=>"Neil", "animal_ids"=>["1", "3"]}, "commit"=>"Create User"}
 Animal Load (0.2ms)  SELECT "animals".* FROM "animals"  WHERE "animals"."id" IN (1, 3)
  (0.1ms)  begin transaction
 SQL (0.2ms)  INSERT INTO "users" ("created_at", "name", "updated_at") VALUES (?, ?, ?)  [["created_at", "2015-03-26 15:29:00.478767"], ["name", "Neil"], ["updated_at", "2015-03-26 15:29:00.478767"]]
 SQL (0.1ms)  INSERT INTO "animal_users" ("animal_id", "created_at", "updated_at") VALUES (?, ?, ?)  [["animal_id", 1], ["created_at", "2015-03-26 15:29:00.479833"], ["updated_at", "2015-03-26 15:29:00.479833"]]
 SQL (0.0ms)  INSERT INTO "animal_users" ("animal_id", "created_at", "updated_at") VALUES (?, ?, ?)  [["animal_id", 3], ["created_at", "2015-03-26 15:29:00.480644"], ["updated_at", "2015-03-26 15:29:00.480644"]]
 SQL (0.1ms)  UPDATE "animal_users" SET "updated_at" = ?, "user_id" = ? WHERE "animal_users"."id" = 6  [["updated_at", "2015-03-26 15:29:00.481362"], ["user_id", 8]]
 SQL (0.1ms)  UPDATE "animal_users" SET "updated_at" = ?, "user_id" = ? WHERE "animal_users"."id" = 7  [["updated_at", "2015-03-26 15:29:00.482062"], ["user_id", 8]]
  (2.4ms)  commit transaction

Answer 1

<% Animal.all.each do |animal| %>
   <label>
      <%= check_box_tag "user[animal_ids][]", animal.id, f.object.animals.include?(animal) %>
      <%= animal.name %>
   </label>
<% end %>

并且你必须在你的控制器参数上接受一个带有 id 数组的散列，比如

{  animal_ids: [] }

也许阅读这篇文章可以帮助： http://millarian.com/programming/ruby-on-rails/quick-tip-has_many-through-checkboxes/

Answer 2

collection_check_boxes 是更好的选择：

<%= f.collection_check_boxes(:animal_ids, Animal.all, :id, :name) do |animal| %>
  <%= animal.label { animal.check_box } %>
<% end %>

Answer 3

我更容易理解的另一个使用collection_check_boxex的例子：

<%= f.collection_check_boxes(:animal_ids, Animal.all, :id, :name) do |animal| %>
  <div class="form-check">
    <%= animal.check_box(class: "form-check-input") %>
    <%= animal.label(class: "form-check-label") %>
  </div>
<% end %>

它在 Rails 6

中有效

Rails 4 表格：has_many 通过：复选框

Rails 4 Form: has_many through: checkboxes

ruby-on-rails

has-many-through