Rails 4：如何通过关联使用 has_many 以新形式保存模型

Question

我是 Rails 新手，我正在尝试创建一个新事件，允许用户从数据库中已存在的地点和组织中选择地点和组织。我正在通过关联使用 has_many。现在我无法保存活动，即使我尝试在没有 place_id 或 organization_id 字段的情况下保存活动。

型号：

class Event < ActiveRecord::Base
  belongs_to :organization
  belongs_to :place
end

class Organization < ActiveRecord::Base
  has_many :events
  has_many :places, through: :events
end

class Place < ActiveRecord::Base
  has_many :events
  has_many :organizations, through: :events
end

事件控制器：

 def new
    @event = Event.new
  end

  def create
    @event = Event.new(event_params)
    if @event.save
      render 'show'
    else
      render 'new'
    end
  end

def event_params
    params.require(:event).permit(:name, :description, :contact, :tag_list, :address, :latitude, :longitude, :long_description, :event_date, :start_time, :end_time, :organization_id, :place_id)
  end

新事件视图：

  <%= form_for @event do |f| %>
  <%= f.label :name %>
  <%= f.text_field :name %>
  <%= f.label :event_date %>
  <%= f.text_field :event_date %>
  <%= f.label :start_time %>
  <%= f.text_field :start_time %>
  <%= f.label :end_time %>
  <%= f.text_field :end_time %>
  <%= f.label :description %>
  <%= f.text_field :description %>
  <%= f.label :contact %>
  <%= f.text_field :contact %>
  <%= f.label :address %>
  <%= f.text_field :address %>
  <%= f.label :long_description %>
  <%= f.text_field :long_description %>
  <%= f.label :tag_list, "Tags (separated by commas)" %>
  <%= f.text_field :tag_list %>
  <%= f.submit "Save event", class: "button" %>
<% end %>

我在这里缺少什么来保存事件，最好是组织和地点字段具有组织 ID 和地点 ID 的值？

Answer 1

你应该看看 accepts_nested_attributes_for 和 fields_for。然后把你的模型改成这样

class Organization < ActiveRecord::Base
  has_many :events
  has_many :places, through: :events
  accepts_nested_attributes_for :places
end

class Place < ActiveRecord::Base
  has_many :events
  has_many :organizations, through: :events
  accepts_nested_attributes_for :organizations
end

这样你的 event_params 会是这样的

def event_params

params.require(:event).permit(:name, :description, :contact, :tag_list, :address, :latitude, :longitude, :long_description, :event_date, :start_time, :end_time, places_attributes: [:some_attribute_of_place,..], organizations_attributes: [:some_attribute_of_organization,..)

end

你的表格可以写成，

<%= form_for @event do |f| %>
  <%= f.label :name %>
  <%= f.text_field :name %>
  <%= f.label :event_date %>
  <%= f.text_field :event_date %>
  <%= f.label :start_time %>
  <%= f.text_field :start_time %>
  <%= f.label :end_time %>
  <%= f.text_field :end_time %>
  <%= f.label :description %>
  <%= f.text_field :description %>
  <%= f.label :contact %>
  <%= f.text_field :contact %>
  <%= f.label :address %>
  <%= f.text_field :address %>
  <%= f.label :long_description %>
  <%= f.text_field :long_description %>
  <%= f.label :tag_list, "Tags (separated by commas)" %>
  <%= f.text_field :tag_list %>

  <%= f.fields_for :places do |p| %>

  ---- your code-----

  <% end %>

  <%= f.fields_for :organizations do |o| %>

  ------ your code-----

  <% end %>

  <%= f.submit "Save event", class: "button" %>

<% end %>