NoMethodError：main：Object（rake任务）的未定义方法“where” - Rails 4答案

【问题标题】：NoMethodError: undefined method `where' for main:Object (rake task) - Rails 4NoMethodError：main：Object（rake任务）的未定义方法“where” - Rails 4
【发布时间】：2014-06-04 15:04:39
【问题描述】：

我有一个带有 cron 作业的 rails 4 应用程序，每天运行一次以下任务：

task :update_packs => :environment do
    @all_users = User.all

    @all_users.each do |user|
        today = where(:created_at => (Time.now.beginning_of_day..Time.now))
        @packs = user.default_packs
        if user.packs.today.count >= 1
            puts "ERROR: User already has a record today."
        else
            user.packs.create(:amount => @packs)
        end
    end
end

但是，当我运行任务时，我收到以下错误：

NoMethodError: undefined method `where' for main:Object
/home/ben/rails_projects/hartwig/lib/tasks/packs.rake:7:in `block (2 levels) in <top (required)>'
/home/ben/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/relation/delegation.rb:46:in `each'
/home/ben/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.0/lib/active_record/relation/delegation.rb:46:in `each'
/home/ben/rails_projects/hartwig/lib/tasks/packs.rake:6:in `block in <top (required)>'
/home/ben/.rvm/gems/ruby-2.1.1/bin/ruby_executable_hooks:15:in `eval'
/home/ben/.rvm/gems/ruby-2.1.1/bin/ruby_executable_hooks:15:in `<main>'
Tasks: TOP => update_packs

我尝试将 where 替换为 conditions，但我得到了同样的错误。有任何想法吗？

【问题讨论】：

标签： ruby-on-rails ruby rake where

【解决方案1】：

这样写你的循环：

@all_users.each do |user|
  @packs = user.default_packs
  if user.packs.where(:created_at => (Time.now.beginning_of_day..Time.now).exists?
    puts "ERROR: User already has a record today."
  else
    user.packs.create(:amount => @packs)
  end
end

不过，我强烈建议为您的 Pack 模型添加范围：

class Pack < ActiveRecord::Base
  scope :today, -> { where(:created_at => (Time.now.beginning_of_day..Time.now)) }
end

那么你的任务应该是这样的：

  @all_users.each do |user|
  @packs = user.default_packs
  if user.packs.today.exists?
    puts "ERROR: User already has a record today."
  else
    user.packs.create(:amount => @packs)
  end
end

【讨论】：

【解决方案2】：

您需要在要查询的课程上致电where。（例如User.where(...)）

例如，要遍历今天创建的所有用户，您应该这样做：

task :update_packs => :environment do
  User.where(:created_at => (Time.now.beginning_of_day..Time.now)).each do |user|
    ...
  end
end

【讨论】：