驗證唯一性方法僅遵循一次

Question

我創建了一個與用戶（設計）完全相同的以下系統。 我跟着Ryan Bates Rails演員陣容http://railscasts.com/episodes/163-self-referential-association

在這段代碼中我們可以添加很多次相同的用戶，我想阻止人們添加爲朋友的時間。

例如，當User1添加了User2時，鏈接將被阻止。 我給你一些代碼來理解。

遷移被稱爲友誼之品

class CreateFriendships < ActiveRecord::Migration 
    def change 
    create_table :friendships do |t| 
     t.integer :user_id 
     t.integer :friend_id 

     t.timestamps null: false 
    end 
    end 
end 

爲用戶的模型是

has_many :friendships 
has_many :friends, :through => :friendships 

作爲朋友的模型是

belongs_to :user 
belongs_to :friend, :class_name => "User" 

友誼控制器

class FriendshipsController < ApplicationController 
    def create 
    @friendship = current_user.friendships.build(:friend_id => params[:friend_id]) 
    if @friendship.save 
     flash[:notice] = "Added friend." 
     redirect_to current_user 
    else 
     flash[:error] = "Unable to add friend." 
     redirect_to current_user 
    end 
    end 

def destroy 
    @friendship = current_user.friendships.find(params[:id]) 
    @friendship.destroy 
    flash[:notice] = "Removed friendship." 
    redirect_to current_user 
    end 
end 

謝謝您的幫助

Answer 1

你可以做這樣的事情在你的控制器：

... 
def create 
    if current_user.friendships.where(friend_id: params[:friend_id]).any? 
    flash[:error] = "You already have added this user." 
    redirect_to current_user 
    else 
    @friendship = current_user.friendships.build(:friend_id => params[:friend_id]) 
    if @friendship.save 
     flash[:notice] = "Added friend." 
     redirect_to current_user 
    else 
     flash[:error] = "Unable to add friend." 
     redirect_to current_user 
    end 
    end 
end 
... 

而且在你的意見，你可以做這樣的事情：

... 
if current_user.id == user.id 
    link_to 'Your Profile', '#!' 
elsif current_user.friendships.where(friend_id: user.id).any? 
    link_to 'Friends', '#!' 
else 
    link_to 'Add Friend', path_here 
end 
...