Question

我有两个模型employee和in_outs。这些关联是employee has many in_outs和in_out belongs to employee。我想显示所有的attendance employees。为此我的current logic就是这个。

控制器动作中的

逻辑：

def view_all_employee_attendance
  employees = Employee.all
  @all_employess_punch_in_outs = []
  employees.each do |employee|
    @all_employess_punch_in_outs << employee.in_outs.where('date >= ? and date <= ?', Date.today.at_beginning_of_month, Date.today)
  end
end

并在视野中：

      <tbody>
        <% @all_employess_punch_in_outs.each do |punch_record| %>
          <tr>
            <td><%= punch_record.employee.name %></td>
            <td><%= punch_record.check_in %></td>   
            <td><%= punch_record.check_out %></td>   
          </tr>
        <% end %>
      </tbody>

在我的view再次queries正在执行的情况下。如何使用optimise在view和action中进行此查询eagerloading？

Answer 1

由于视图中的以下行，您的查询会再次被调用： punch_record.employee.name。

为了急切加载employee，您需要将查询修改为：

def view_all_employee_attendence
  @employee_in_outs = Employee.all.includes(:in_outs).where('in_outs.date >= ? and in_outs.date <= ?', Date.today.at_beginning_of_month, Date.today)
end

includes documentation。

Answer 2

将查询行更改为此。这将使用where子句急切加载您的所有in_outs，以便您只运行一个查询。这样就可以使您的视图得到优化，并且不必在N+1个查询中运行in_out每次您请求employees = Employee.joins(:in_outs).all.where('in_outs.date >= ? and in_outs.date <= ?', Date.today.at_beginning_of_month, Date.today).preload(:in_outs)

时

{{1}}

什么是查询的最佳方式？

2 个答案: