Question

我有一个模型Journey，有很多用户（驱动程序）。我希望能够在accepts_nested_attributes_for的帮助下添加和删除旅程中的驱动程序。当我添加驱动程序时，我想向用户显示＆lt; select＆gt;在那里，她可以选择其中一个用户作为属于该特定旅程的驾驶员之一。我来得那么久了：

# Models
class Journey < ActiveRecord::Base
  has_many :drivers
  accepts_nested_attributes_for :drivers, :allow_destroy => true
  has_many :users, :through => :drivers
  accepts_nested_attributes_for :users
end

class Driver < ActiveRecord::Base
  belongs_to :journey
  belongs_to :user
end

class User < ActiveRecord::Base
  has_many :drivers
  has_many :journeys, :through => :drivers
end

# View _form.html.erb
<% form_for(@journey) do |f| %>
  <%= f.error_messages %>
  <% f.fields_for :drivers do |d| %>
    <%= render :partial => 'driver', :locals => { :f => d } %>
  <% end %>
  <p><%= f.submit 'Submit' %></p>
<% end %>

# View _driver.html.erb
<p><%= f.collection_select(:id, User.all, :id, :name)%></p>

错误说：

ActiveRecord::AssociationTypeMismatch in JourneysController#create
Driver(#2185315860) expected, got Array(#2151950220)

我怀疑我的_driver.html.erb错了，但我不知道如何修复它。你能帮我解决一些提示吗？

Answer 1

您的_driver.html.erb应如下所示：

<%= f.collection_select(:user_id, User.all, :id, :name) %>

但我不确定这是否会导致错误。

当我使用accepts_nested_attributes_for嵌套模型时，我这样做：

# Models
class Journey < ActiveRecord::Base
  has_many :drivers
  accepts_nested_attributes_for :drivers, :allow_destroy => true
  has_many :users, :through => :drivers
end

class Driver < ActiveRecord::Base
  belongs_to :journey
  belongs_to :user
  accepts_nested_attributes_for :users
end

所以你可以有这样的表格：

<% form_for @journey do |f| %>
   <% fields_for :drivers do |d| %>
      <% fields_for :user do |u| %>
        <%= u.text_field :name %>
        ...
      <% end %>
    <% end %>
<% end %>

accepts_nested_attributes_for和collection_select如何构建视图？

1 个答案: