销毁 has_many :through 不适用于 link_to 助手

Question

我正在 Rails 4 中开发一个简单的项目管理工具，让我头疼的部分主要有三个模型：Projects、Users 和 Memberships。

用户可以有很多项目，项目也可以有很多用户。我通过以下方式在项目和用户之间实现了has_many through 成员关系：

项目：

class Project < ActiveRecord::Base
  has_many :memberships
  has_many :users, through: :memberships
end

用户：

class User < ActiveRecord::Base
   has_many :memberships
   has_many :projects, through: :memberships
end

会员：

class Membership < ActiveRecord::Base
    belongs_to :user
    belongs_to :project
end

到目前为止，我还没有在 Stack Overflow 上看到它，但我为 Memberships 创建了一个单独的控制器，只有 :create 和 :destroy。 到目前为止，:create 似乎工作得很好。

主要问题在于会员资格的销毁功能。 我实现的destroy函数是：

def destroy
    Membership.find(:id).destroy
    redirect_to current_project || request.referer
end

rake routes 说会员路径存在，但以下尝试给了我：

我尝试使用link_to helper 删除会员资格：

<%= link_to "delete", membership, method: :delete %> 
EDIT: error: undefined local variable or method `membership' 

<%= link_to "delete", @membership, method: :delete %>
EDIT: error: Sorry something went wrong --> goes to /memberships

<%= link_to "delete, membership_path(@membership), method: :delete %>
EDIT: error No route matches {:action=>"destroy", :controller=>"memberships", :id=>nil} missing required keys: [:id]

这都给出了错误。

编辑：还应要求提供projects_controller #show 功能

def show
    @user = current_user
    @project = current_user.projects.find(params[:id])
    @members = @project.users
    @projects = @user.projects
    @membership = @project.memberships.build if logged_in?
    @memberships = @project.memberships
end 

如何确保删除具有@project.membership_ids 中关联 ID 的成员资格？我应该包含某些额外的参数吗？

Answer 1

resources :memberships, only: [:create, :destroy]

更新

不知道我之前是怎么错过的，在你的销毁操作中你有Membership.find(:id).destroy。它应该利用参数并且更符合以下原则：

# MembershipsController
def destroy
    @membership = Membership.find(params[:id])
    if @membership.destroy
        redirect_to current_project || request.referer
    else
        #
    end
end

您的ProjectsController 的显示操作未将@membership 定义为Membership 对象。

def show
    @user = current_user
    @project = @user.projects.find(params[:id])
    @membership = Membership.find_by user: @user, project: @project

    # build is used for nested attributes, not sure why you'd have this in a show action...
    # @project.memberships.build if logged_in?

    # the following are redundant.
    @projects = @user.projects
    @members = @project.users
    @memberships = @project.memberships
end 

在视图中：<%= link_to "delete", @membership, method: :delete %>

如果您希望在删除父项时销毁项目或用户的所有成员资格，请对您的 User 和 Project 模型进行以下更改：

class Project < ActiveRecord::Base
    has_many :memberships, dependent: :destroy
    has_many :users, through: :memberships
end

class User < ActiveRecord::Base
    has_many :memberships, dependent: :destroy
    has_many :projects, through: :memberships
end

Answer 2

您的代码不起作用的原因是您没有指定link_to 的路径。我认为您不需要@membership，所以我将其编辑了。

<%= link_to "delete", membership_path(@membership), method: :delete %>