ruby-on-rails - 从参与事件的数据库中获取所有用户

Question

我目前面临以下问题:用户能够创建事件。其他用户有可能参与该事件。我现在希望已经参与事件的用户将列在事件 View 中。所以我尝试的是用 activity_id 在 activity_controller 的 show 方法中显示所有参与事件的用户。

模型关系如下:

 class Activity < ActiveRecord::Base
  has_many :users, through: :participations
  belongs_to :user
  has_many :participations
  has_many :reviews

end


 class Participation < ActiveRecord::Base
  belongs_to :user
  belongs_to :activity
  has_many :activities
end




 class User < ActiveRecord::Base
  has_many :activities
  has_many :participations
  has_many :reviews

end

我的事件 Controller 正在执行以下操作:

class ActivitiesController < ApplicationController
  before_action :set_activity, only: [:show, :edit, :update, :destroy]
  before_action :authenticate_user!, except: [:show]

  def index
    @activities = Activity.all
  end

  def show
    @participated = Participation.where("activity_id = ? AND user_id = ?", @activity.id, current_user.id).present? if current_user
    @reviews = @activity.reviews
    @hasReview = @reviews.find_by(user_id: current_user.id) if current_user

    @participant = Participation.where (:activity_id == 'activity_id')
  end



  def new
    @activity = current_user.activities.build
  end

  def create
    @activity = current_user.activities.build(activity_params)

    if @activity.save

      redirect_to edit_activity_path(@activity), notice: "We want to give you a warm welcome!"

    else
      render :new, notice: "Something seems to be missing!"
    end
  end

  def edit
    if current_user.id == @activity.user.id
      redirect_to root_path
    end
  end

  def update
    if @activity.update(activity_params)
      redirect_to edit_activity_path(@activity), notice: "Updated!"
    else
      render :edit
    end
  end

  def destroy
    @activity = Activity.find(params[:id])

    if @activity.destroy
      redirect_to activities_path, notice: "Deleted!"
    end
  end

  private

  def set_activity
    @activity = Activity.find(params[:id])
  end


  def activity_params
    params.require(:activity).permit(:activity_name,
                                     :activity_starttime,
                                     :activity_duration,
                                     :activity_intensity,
                                     :activity_distance,
                                     :activity_topography,
                                     :activity_address,
                                     :activity_track,
                                     :activity_summary)

  end
end

同时参与 Controller 处理这个:

    class ParticipationsController < ApplicationController
  before_action :authenticate_user!

  def preload
    activity= Activity.find(params[:activity_id])
    participations = activity.participations
    render json: participations
  end

  def create

    if Participation.exists?(user_id: current_user.id)

      redirect_to activities_path(@activity), notice: "Du nimmst bereits teil!"

    else

      @participation = current_user.participations.create(participation_params)
      redirect_to @participation.activity, notice: "Klasse, du nimmst nun teil!"

    end

  end


  def participant
    @participant = user.participations
  end

  def your_matches
    @matches = current_user.participations
  end

  def your_participations
    @activities = current_user.activities
  end

  private

  def participation_params
    params.permit(:activity_id, :status)
  end
end

在我看来，我调用了 Controller :

<div class="row">
  <div class="col-md-12">
    <h3>Wer kommt bis jetzt mit? </h3>


    <table>
      <tr>
        <th></th>
      </tr>

      <% @participant.each do |participant| %>

          <tr>
            <td><%= participant.user.fullname %></td>
          </tr>

      <% end %>

    </table>

  </div>
</div>

这为我提供了参与任何事件的所有用户的列表。但我现在唯一想要的是显示所有参与请求事件的用户。我会说我的关系应该正常工作，因此我想我只需要一个小提示就可以解决问题。在我的应用程序的另一点，我已经得到了一个列表，我可以在其中显示参与的用户，但由于 Controller 不同，我无法从事件 Controller 中调用它。总而言之，这会导致错误，因为我无法从 activities_view 调用 participations_controller。

<div class="panel-body">
    <% @activities.each do |activity| %>
      <% activity.participations.each do |participation| %>


      <div class="row">

        <div class="col-md-3">
          <%= link_to user_path(participation.user) do %>
              <%= participation.user.fullname %>
          <% end %>
      </div>

非常感谢任何帮助并提前致谢!

编辑 1:有关数据库包含的内容的更多信息:

class CreateParticipations < ActiveRecord::Migration
  def change
    create_table :participations do |t|
      t.references :user, index: true, foreign_key: true
      t.references :activity, index: true, foreign_key: true

      t.string :status

      t.timestamps null: false
    end
  end
end


class CreateActivities < ActiveRecord::Migration
  def change
    create_table :activities do |t|

      t.string :activity_name
      t.datetime :activity_starttime
      t.time :activity_duration
      t.string :activity_intensity
      t.integer :activity_distance
      t.string :activity_topography
      t.string :activity_address
      t.string :activity_track
      t.string :activity_summary


      t.references :user, index: true, foreign_key: true

      t.timestamps null: false
    end
  end
end

Answer 1

当你在你的Participation模型中添加一个has_many和belongs_to relantionship并引用Activity时，我还是不明白模型。

如果你有:

• 用户 有_many 次参与
• 事件 has_many参与
• 参与belongs_to用户和belongs_to事件

然后您可以在查询中加入 User 和 Participation 并尝试让所有参与特定事件的用户像:

User.joins(:participations).where('participations.activity_id = 1')

编辑:我已经测试了您的代码，没有触及模型、迁移等任何内容。我插入了一些示例记录，例如:

User.new(fullname: 'seb', ...).save
User.new(fullname: 'sab', ...).save
User.new(fullname: 'frank', ...).save

Activity.new(name: 'yoga', user_id: 1).save
Activity.new(name: 'pilates', user_id: 1).save
Activity.new(name: 'tennis', user_id: 2).save
Activity.new(name: 'etc etc etc', user_id: 3).save

Participation.new(user_id: 1, activity_id: 1).save
Participation.new(user_id: 2, activity_id: 1).save
Participation.new(user_id: 3, activity_id: 1).save

然后我运行查询，有 3 个用户参与了 ID 为 3 的事件:

User.joins(:participations).where('participations.activity_id = 1').pluck(:fullname)

然后我得到:

SELECT "users"."fullname" FROM "users" INNER JOIN "participations" ON "participations"."user_id" = "users"."id" WHERE (participations.activity_id = 1)
# => ["seb", "sab", "frank"]