如何打印 rails 应用程序中每个条目的待处理任务计数

Question

我已经生成了项目、阶段、任务和 sub_task 脚手架。每个项目有很多阶段，每个阶段有很多任务，每个任务有很多 sub_task。对应的table已经在数据库中生成。计划开始和计划结束日期字段已添加到阶段、任务和 sub_task table。现在我想在 project#index 上添加一列，它将显示每个项目的待处理阶段+任务+sub_task 的计数。我在 project#show 中实现了这个目标，但我无法在 project#index 中做到这一点...

projects_controller.rb


  def index
    @projects = current_user.projects.all.order("created_at DESC").paginate(page: params[:page], per_page: 15)

  end

  def show
    @project = Project.includes(stages: {tasks: {sub_tasks: {sub_sub_tasks: :sub_three_tasks}}}).find(params[:id])
    @stages = @project.stages

    @tasks = Task.where(stage_id: @stages.ids)
    @sub_tasks = SubTask.where(task_id: @tasks.ids)


    stage_counter = 0
    task_counter = 0
    sub_task_counter = 0

    @stages.each{|s| stage_counter += 1 if s.planned_end_date.past? && s.status == 0 || s.planned_end_date.past? && s.status == 2}
    @tasks.each{|s| task_counter += 1 if s.planned_end_date.past? && s.status == 0 || s.planned_end_date.past? && s.status == 2}
    @sub_tasks.each{|s| sub_task_counter += 1 if s.planned_end_date.past? && s.status == 0 || s.planned_end_date.past? && s.status == 2}


    @count = stage_counter + task_counter + sub_task_counter

end

index.html.erb（项目）

  <table>
    <thead>
      <tr>
        <th>Project Name</th>
        <th>Activity Status</th>
      </tr>
    </thead>

    <tbody>
      <% @projects.each do |project| %>
        <tr>
          <td><%= project.project_name %></td>
          <td class="alert"><%= @total_count.to_s + " Activity Pending" %></td>
        </tr>
      <% end %>
    </tbody>
  </table>

Answer 1

要是我们有像数据库这样擅长计算行数的东西就好了...

class Project < ApplicationRecord
  has_many :stages
  has_many :tasks, through: :stages
  def self.with_counts
    # subquery to fetch a count of the stages
    stages = Stage
              .where('stages.project_id = projects.id')
              .where('stages.planned_end_date < ?', Time.current)
              .select('COALESCE(COUNT(*), 0)')
              .where(status: [0,2])
    # subquery to fetch a count of the tasks
    tasks = Task
              .joins(:stage)
              .select('COALESCE(COUNT(*), 0)')
              .where(status: [0,2])
              .where('tasks.planned_end_date < ?', Time.current)
              .where('stages.project_id = projects.id')
    select(
      "projects.*",
      "(#{stages.to_sql}) + (#{tasks.to_sql}) AS total_count"
    ).group(:id)
  end
end

这执行单个查询并通过子查询选择 total_count：

SELECT projects.*,
       (SELECT COALESCE(COUNT(*), 0)
        FROM   "stages"
        WHERE  ( stages.project_id = projects.id )
               AND ( stages.planned_end_date < '2020-03-06 15:14:01.936655' )
               AND "stages"."status" IN ( 0, 2 ))
       + (SELECT COALESCE(COUNT(*), 0)
          FROM   "tasks"
                 INNER JOIN "stages"
                         ON "stages"."id" = "tasks"."stage_id"
          WHERE  "tasks"."status" IN ( 0, 2 )
                 AND ( tasks.planned_end_date < '2020-03-06 15:14:01.941389' )
                 AND ( stages.project_id = projects.id )) AS total_count
FROM   "projects"
GROUP  BY "projects"."id"
ORDER  BY "projects"."id" ASC
LIMIT

我什至不会碰你的 'SubTask' class 因为那是一个 FUBAR 尝试 self referential association.

应该做什么

如何打印 rails 应用程序中每个条目的待处理任务计数

how to print pending tasks count for each entries in rails application

ruby-on-rails

ruby-on-rails-5