rails中的关联模型

Question

我是刚接触过红宝石的rails，我要创建在线租赁系统。

这是位置基模型。

app/models/state.rb
Class State < ActiveRecord::Base
has_many :provinces
end

app/models/province.rb
Class Province < ActiveRecord::Base
belongs_to :state
has_many :districts
end

app/models/district.rb
Class District < ActiveRecord::Base
belongs_to :province
has_many :cities
end

app/models/city.rb
Class City < ActiveRecord::Base
belongs_to :district
end

的第一个问题是如何在下面显示

• 阿拉斯加
• 加利福尼亚
  • 洛杉矶
  • 弗雷斯诺
    • 辛科塔(弗雷斯诺)
    • 哈蒙德(弗雷斯诺)
    • 梅尔文(弗雷斯诺)
      • 梅尔文1
      • 梅尔文2

​

​

​

• 亚利桑那州
• 科罗拉多州

的第二个问题是，如何创建全模型

加利福尼亚>> Fresno >> Melvin >> Melvin 1

Answer 1

您可能希望在数据对象中引入层次结构。这可以通过几种方式来完成。看看祖先宝石

如果你想硬编码的话：

# locations_controller.rb
def index
  @locations = State.all
end

# app/views/locations/index.html.erb
<ul>
  <%= render @locations %>
</ul>

# app/views/locations/_state.html.erb
<li>
  <%= state.name %>
  <% if state.provinces.present? %>
    <ul>
      <%= render state.provinces %>
    </ul>
  <% end %>
</li>

# app/views/locations/_province.html.erb
<li>
  <%= province.name %>
  <% if province.districts.present? %>
    <ul>
      <%= render province.districts %>
    </ul>
  <% end %>
</li>

# app/views/locations/_district.html.erb
<li>
  <%= district.name %>
  <% if district.cities.present? %>
    <ul>
      <%= render district.cities %>
    </ul>
  <% end %>
</li>   

# app/views/locations/_city.html.erb
<li>
  <%= city.name %>
</li>  

对于面包屑，您需要在每个模型中引入一个祖先方法。例如：

class City
  ...
  def ancestry
    district.ancestry << self
  end
  ...
end

# ... other classes

class State
  ...
  def ancestry
    [self]
  end
end

然后，您可以将面包屑部分呈现出来。

# app/views/layout.html.erb
<%= render partial: 'shared/breadcrumbs', locals: { ancestry: @some_instance.
def breadcrumbs(ancestry)
  ancestry
end

# app/views/shared/_breadcrumbs.html.erb
<ul>
  <% ancestry.each do |location| %>
    <li>
      <%= link_to location.name, url_for(location) %>
    </li>
  <% end %>
</ul>