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嗨，我的应用程序的 has_many through 关系遇到了一点麻烦，希望能找到一些帮助。所以我有用户和讲座。讲座由一位用户创建，但随后其他用户可以“加入”已创建的讲座。用户有他们自己创建的讲座的个人资料提要，也有朋友创建的讲座的提要。然而，这个问题不是关于创建讲座，而是“加入”已经创建的讲座。我创建了一个“lecturerelationships”模型和控制器来处理 Lectures 和已加入的用户（我称之为“actives”）之间的这种关系。用户还必须“退出”讲座（通过单击“退出”或导航到标题导航链接之一）。

我有： Users.rb 模型 Lectures.rb 模型 Users_controller Lectures_controller

然后是以下模型

讲师关系.rb

class lecturerelationship < ActiveRecord::Base
  attr_accessible :active_id, :joinedlecture_id

  belongs_to :active, :class_name => "User"
  belongs_to :joinedlecture, :class_name => "Lecture"

  validates :active_id, :presence => true
  validates :joinedlecture_id, :presence => true

end

LectureRelationships_controller.rb

class LecturerelationshipsController < ApplicationController
  before_filter :signed_in_user

  def create
   @lecture = Lecture.find(params[:lecturerelationship][:joinedlecture_id])
   current_user.join!(@lecture)
   redirect_to @lecture
  end

 def destroy
  @lecture = Lecturerelationship.find(params[:id]).joinedlecture
  current_user.exit!(@user)
  redirect_to @user
 end

end

已（由朋友）创建的讲座显示在以下文件中的用户提要中

_activity_item.html.erb

<li id="<%= activity_item.id %>">
  <%= link_to gravatar_for(activity_item.user, :size => 200), activity_item.user %><br   clear="all">
  <%= render :partial => 'shared/join', :locals => {:activity_item => activity_item} %>
  <span class="title"><%= link_to activity_item.title, lecture_url(activity_item)  %></span><br clear="all">
  <span class="user">
   Joined by <%= link_to activity_item.user.name, activity_item.user %>
  </span><br clear="all">
  <span class="timestamp">
   <%= time_ago_in_words(activity_item.created_at) %> ago.
  </span>
  <% if current_user?(activity_item.user) %>
    <%= link_to "delete", activity_item, :method => :delete,
                                     :confirm => "Are you sure?",
                                     :title => activity_item.content %>
  <% end %>
</li>

然后你会看到我链接到上面的“共享/加入”部分，可以在下面的文件中看到

_join.html.erb

<%= form_for(current_user.lecturerelationships.build(:joinedlecture_id =>  activity_item.id)) do |f| %>
  <div>
   <%= f.hidden_field :joinedlecture_id %>
  </div>
  <%= f.submit "Join", :class => "btn btn-large btn-info" %>
<% end %>

可能需要的更多文件：

配置/路由.rb

SampleApp::Application.routes.draw do
  resources :users do
    member do
    get :following, :followers, :joined_lectures
  end
end

resources :sessions, :only => [:new, :create, :destroy]
resources :lectures, :only  => [:create, :destroy, :show]
resources :relationships, :only => [:create, :destroy] #for users following each other
resources :lecturerelationships, :only => [:create, :destroy] #users joining existing lectures

所以会发生什么是讲座出现在我的activity_feed中，底部有一个加入按钮选项......这应该创建一个“活动”和“joinedlecture”的讲座关系（显然应该来自用户和讲座课程。但是当我点击加入按钮时我得到的错误如下：

ActiveRecord::StatementInvalid in LecturerelationshipsController#create

SQLite3::ConstraintException: constraint failed: INSERT INTO "lecturerelationships"     ("active_id", "created_at", "joinedlecture_id", "updated_at") VALUES (?, ?, ?, ?)

我还包括了我的用户模型（似乎错误指的是它）user.rb

class User < ActiveRecord::Base
  attr_accessible :email, :name, :password, :password_confirmation
  has_secure_password
  has_many :lectures, :dependent => :destroy


  has_many :lecturerelationships, :foreign_key => "active_id", :dependent => :destroy
  has_many :joined_lectures, :through => :lecturerelationships, :source =>    :joinedlecture

  before_save { |user| user.email = email.downcase }
  before_save :create_remember_token

  validates :name, :presence => true, :length => { :maximum => 50 }
  VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  validates :email, :presence => true,
        :format => { :with => VALID_EMAIL_REGEX },
        :uniqueness => { :case_sensitive => false }
  validates :password, :presence => true, :length => { :minimum => 6 }
  validates :password_confirmation, :presence => true

  def activity
    # This feed is for "My Activity" - basically lectures i've started
    Lecture.where("user_id = ?", id)
  end

  def friendactivity
     Lecture.from_users_followed_by(self)
  end

  # lECTURE TO USER (JOINING) RELATIONSHIPS
  def joined?(selected_lecture)
    lecturerelationships.find_by_joinedlecture_id(selected_lecture.id)
  end

  def join!(selected_lecture)
    lecturerelationships.create!(:joinedlecture_id => selected_lecture.id)
  end

  def exit!(selected_lecture)
   lecturerelationships.find_by_joinedlecture_id(selected_lecture.id).destroy
  end


end

感谢您提供的所有帮助 - 我会在这里待一段时间，所以如前所述，我非常感谢可能有时间与我一起解决问题的人......

4

2 回答 2

2

我将从以下模型开始，对成员资格表使用 Enrollment。
类命名对此至关重要。

class User < ActiveRecord::Base
  has_many :enrollments
  has_many :users, :through => :enrollments
end

class Lecture < ActiveRecord::Base
  has_many enrollments
  has_many users, :through => :enrollments
end

class Enrollment < ActiveRecord::Base
  belongs_to :user
  belongs_to :lecture
end

rails 的主要技巧是使用正确的名称并遵循约定并让框架为您完成大部分工作。走出这条路，错误可能无穷无尽，代码很快就会变得混乱:)

于 2012-06-08T22:36:22.120 回答
1

看起来你的 _join.html.erb 用来build形成一个新的lecturerelationships关联，然后join!调用用来create在同一个对象上建立另一个。我的猜测是第二个调用中断了由第一个调用启动的事务，这就是您收到database is locked: commit transaction错误的原因。

我认为将此类代码排除在您的视图之外是一种很好的做法。

于 2012-06-08T22:14:07.357 回答