如何在创建操作中使用find_or_create？

Question

我想在我的游戏日期控制器中使用find_or_create方法。当参数在game_date_params时，我不知道如何在创建动作中使用该方法。任何建议如何从game_date_params中提取日期？

class GameDatesController < ApplicationController
  before_action :authenticate_user!
  before_action :authenticate_admin

  def index
    @game_dates = GameDate.all
    @showcases  = Showcase.joins(:game_dates)
  end

  def new
    @game_date = GameDate.new
    @game_date.referee_stats.build
  end

  def create
    @game_date = GameDate.new(game_date_params)
    if @game_date.save
      redirect_to showcases_path
      flash[:success] = "Game date created"
    else
      render 'new'
    end
  end

  def show
    @game_date = GameDate.find(params[:id])
  end

  def destroy
    @game_date = GameDate.find(params[:id]).destroy
    redirect_to root_url
    flash[:success] = "Game date deleted"
  end


  private

  def game_date_params
    params.require(:game_date).permit(:date, referee_stats_attributes: [ :games_count, :showcase_id ])
  end

这是POST操作的输出：

2016-04-01 10:21:44 0200开始POST“/game_dates”127.0.0.1由GameDatesController#创建为HTML参数：｛“utf8”=

Answer 1

创建动作用于在调用新动作后创建对象，更新动作用于编辑。混合创建

Answer 2

它应该是这样的：

def create
    @game_date = GameDate.find_or_create_by(game_date_params)
    if @game_date.present?
      redirect_to showcases_path
      flash[:success] = "Game date created"
    else
      render 'new'
    end
 end

Answer 3

GameDate.find_or_create_by（game_date_params） 会找到所有game_date_params的记录，因此您可以通过查找特定参数（如日期）并通过块为其分配其余属性来做到这一点。例如：

def create
  # find or initialize the record
  @game_date = GameDate.find_or_initalize_by(date: game_date_params[:date]) do |game_date|
    # Accept nested attributes as well
    game_date.assign_attributes(game_date_params)
  end

  if @game_date.save
    redirect_to showcases_path
    flash[:success] = "Game date created"
  else
    render 'new'
  end
end

另请参见：find_or_create_by和AttributesAssignment API文档