Question

我有这些模特：

class Users < ActiveRecord::Base      
  has_many  :members
  has_many  :organizations, :through => :members
end

class Organizations < ActiveRecord::Base 
  has_many  :members
  has_many  :users, :through => :members 
end

class Members < ActiveRecord::Base 
 belongs_to :organizations
 belongs_to :users
end

我想创建一个会员记录如下：

用户登录
导航到特定组织＆＃39; show＆＃39;页
点击标有＆＃39;加入＆＃39;

我已经阅读了网站上的几个帖子，提出了类似的问题;但是，大多数是在同时创建其中一个记录时。这是我尝试过的：

在我的组织的控制器中，我创建了一个连接方法：

# PATCH/PUT /organizations/1/join
def join
  @membership = @organization.members.new(user_id: current_user.id)
  if @membership.save
    flash[:success] = "Your have successfully joined #{@organization.name}!"
    redirect_to @organization
  else
    flash[:error] = "There was an error."
    render 'show'
  end
end

在我的路线文件中，我添加了一个加入链接：

resources :organizations do
  member do
    post :join
  end
end

在我的组织的展示页面上，我添加了如下链接：

<% if @organization.members.where("user_id = ?", @current_user).exists? %>
  # Unjoin link
<% else %>
  <%= link_to 'Join!', join_organization_path,
                       :method => "post" %>
<% end %>

这是我的服务器日志错误：

Started POST "/organizations/2/join"
Processing by OrganizationsController#join as HTML
Parameters: {"authenticity_token"=>"...=", "id"=>"2"}
Completed 500 Internal Server Error in 1ms

NoMethodError (undefined method `members' for nil:NilClass):
app/controllers/organizations_controller.rb:47:in `join'

感谢您的帮助。

Answer 1

在@organization方法中设置实例变量join。

def join
  @organization = Organization.find(params[:id]) ## Set @organization
  @membership = @organization.members.new(user_id: current_user.id)
  if @membership.save
    flash[:success] = "Your have successfully joined #{@organization.name}!"
    redirect_to @organization
  else
    flash[:error] = "There was an error."
    render 'show'
  end
end

您收到NoMethodError (undefined method 'members' for nil:NilClass)错误，因为@organization实例变量为nil（未设置）且您在members对象上调用nil方法。

如果您的控制器中设置了before_action回调设置以设置@organization变量，那么您只需添加join作为选项。

Rails：通过链接创建关联记录

1 个答案: