ruby-on-rails - ||如何工作？ : @client = client. 查找(参数[:client_id] || 参数[:id])

Question

rails 新手。按照多态关联的教程，我遇到了这个以在create 和destroy 中设置@client。

@client = Client.find(params[:client_id] || params[:id])

我通常只习惯你只能找到@client = Client.find(params[:id])

那么这在有两个参数的情况下是如何工作的？ ||如何工作？

FavoriteClientsController.rb:

class FavoriteClientsController < ApplicationController

  def create
    @client = Client.find(params[:client_id] || params[:id])

    if Favorite.create(favorited: @client, user: current_user)
      redirect_to @client, notice: 'Leverandøren er tilføjet til favoritter'
    else
      redirect_to @client, alert: 'Noget gik galt...*sad panda*'
    end
  end

  def destroy
    @client = Client.find(params[:client_id] || params[:id])

    Favorite.where(favorited_id: @client.id, user_id: current_user.id).first.destroy
    redirect_to @client, notice: 'Leverandøren er nu fjernet fra favoritter'
  end

end

Controller 完整代码，型号可见here

使用 rails 5

Answer 1

表达式:params[:client_id] || params[:id] 等同于:

if params[:client_id]
  params[:client_id]
else
  params[:id]
end