Rails如何从关联的模型中添加记录新页面

Question

I have 2 models setup like so:

class Campaign < ApplicationRecord
  has_many :cities
  belongs_to :user
end

class City < ApplicationRecord
  belongs_to :campaign
end

Controller:

  def new
    @campaign = current_user.campaigns.build
    @cities = @campaign.cities
  end

I would like users to be able to create and edit cities directly from the campaign page. I am not sure how to do this, here is my attempt. How do I access city.name? :name is the param key for @campaign

<%= form_for @campaign do |f| %>
  <%= f.label "Name" %>
  <br />
  <%= f.text_field :name %>
  <br /> <br />

  <%= f.label "Titles" %>
  <br />
  <%= f.text_area :titles, cols: 80, rows: 20 %>
  <br /> <br />

  <%= f.label "Sentences" %>
  <br />
  <%= f.text_area :sentences, cols: 80, rows: 20 %>
  <br /> <br />

  <%= f.label "Keywords" %>
  <br />
  <%= f.text_area :keywords, cols: 80, rows: 20 %>
  <br /> <br />

  <% if @cities.count > 0 %>
    <h2>Cities</h2>
    <% for city in @cities %>
      <%= f.label "City name:" %>
      <br />
      <%= f.text_area :name, cols: 80, rows: 20 %>
    <% end %>
  <% end %>

  <%= f.submit "Submit" %>
<% end %>

Answer 1

I was able to do this with:

   <% if @cities.count > 0 %>
    <h2>Cities</h2>
    <% for city in @cities %>
      <%= form_for city do |f| %>
        <%= f.text_area :name, cols: 20, rows: 1 %>
        <%= f.text_area :phone_number, cols: 20, rows: 1 %>
        <%= f.text_area :zip_code, cols: 20, rows: 1 %><%= f.submit "Submit" %>
      <% end %>
    <% end %>
  <% end %>