Question

我想将数据从db表填充到Rails 4.1中的下拉列表。

#controller code:
class UsersController < ApplicationController
  before_action :set_user, only: [:show, :edit, :update, :destroy]

  def index
    @users = User.all
  end

  def show
  end

  def new
    @user = User.new
  end

  def edit
  end

  def create
    @user = User.new(user_params)

    respond_to do |format|
      if @user.save
        format.html { redirect_to @user, notice: 'User was successfully created.' }
        format.json { render :show, status: :created, location: @user }
      else
        format.html { render :new }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    respond_to do |format|
      if @user.update(user_params)
        format.html { redirect_to @user, notice: 'User was successfully updated.' }
        format.json { render :show, status: :ok, location: @user }
      else
        format.html { render :edit }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end


  def destroy
    @user.destroy
    respond_to do |format|
      format.html { redirect_to users_url, notice: 'User was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private

    def set_user
      @user = User.find(params[:id])
    end
    def user_params
      params.require(:user).permit(:first_name, :last_name, :country)
    end
end

#view code:
<%= f.select :country, @user%>

当我使用上面的代码时，我收到错误

＆＃34;未定义的方法`空？＆＃39;为零：NilClass＆＃34;

这个问题的解决方案是什么？

Answer 1

我已经尝试了以下代码并且工作正常：

<%= f.select :country, User.all.collect {|user| [ user.country,  user.country ] } %>

用户#NoMethodError编辑.undefined方法`empty？'为零：NilClass

1 个答案: