如何建立分页网址​​的路径？

Question

当用户＃1喜欢/评论用户＃2时，用户＃2会收到通知：

通知/ _notifications.html.erb

<%= link_to "", notification_path(notification.id), method: :delete, class: "glyphicon glyphicon-remove" %> <%= link_to Comment.find_by(notification.comment_id).user.name, user_path(Comment.find_by(notification.comment_id).user.id) %> commented on <%= link_to "your activity", (notification.activity_id) %>

但是，当用户＃2点击通知时，自从我删除了activity_path后，它就无法领先，如果我在(notification.activity_id)之前将其放回去，我们会收到错误：

  

没有路线匹配   {：action =＆gt;＆＃34; show＆＃34;，：controller =＆gt;＆＃34;活动＆＃34;，＆gt; ：id =＆gt; nil}缺少必需的键：[：id]

我不知道这是否可行，但点击通知用户＃2将被带到活动i 的分页页面。通过gem will_paginate每页有20个活动，因此，如果评论的活动在第2页上，那么在点击活动时，用户＃2应该定向到：http://0.0.0.0:3000/activities?page=2

这至少会缩小评论在用户活动Feed上的位置。

活动/ index.html.erb

<% @activities.each do |activity| %>
    <%= link_to activity.user.name, activity.user %>
    <%= render "activities/#{activity.trackable_type.underscore}/#{activity.action}", activity: activity %>

      <% activity.activity_likers.each do |user| %>
          <%= user.name %>
      <% end %>

    <%= link_to like_activity_path(:id => activity.id), class: "btn", method: :post do %>
      <span class='glyphicon glyphicon-thumbs-up'></span> Like
    <% end %>

    <%= render "comments/comments", comments: activity.comments %>
    <%= render "comments/form", new_comment: Comment.new(commentable_id: activity.id, commentable_type: activity.class.model_name), create_url: :activity_comments_path %>

<% end %>

<%= will_paginate @activities %>

activities_controller.rb

class ActivitiesController < ApplicationController
    def index
        @activities = Activity.order("created_at desc").paginate(:page => params[:page], :per_page => 20)
    end

    def show
          redirect_to(:back)
    end
end

如果您发现可以执行以下操作，请告知我们。）

更新

class NotificationsController < ApplicationController
    def index
    @notifications = current_user.notifications
    @notifications.each do |notification|
        notification.update_attribute(:read, true)
        activity = Activity.find(notification.activity_id) #Gives "Couldn't find Activity with 'id'=". I then removed ".activity_id" to see what happens next.
            index    = Activity.order(created_at: :desc).index(activity)
            page_number = (index / per_page.to_f).ceil #I am then told "undefined local variable or method `per_page'" so I tried making it :per_page to which I then get: "undefined method `to_f' for :per_page:Symbol"
    end
    end


    def destroy
      @notification = Notification.find(params[:id])
      @notification.destroy
      redirect_to :back
    end
end

的routes.rb

resources :activities do
  resources :comments
  resources :notifications
  member do
    post :like
    post :notifications
  end
end

更新＃2

通知/ index.html.erb

    <% if !@notifications.blank? %>
        <%= render partial: "notifications/notification", collection: @notifications %> 
    <% else %>
        <p>No notifications... yet</p>
    <% end %>

comment.rb

class Comment < ActiveRecord::Base
    after_create :create_notification
  has_many :notifications
  has_many :comment_likes   
  has_many :likers, through: :comment_likes, class_name: 'User', source: :liker
    belongs_to :commentable, polymorphic: true
    belongs_to :user
  belongs_to :activity

private

  def create_notification
    @activity = Activity.find_by(self.activity)
    @user = User.find_by(@activity.user_id).id
      Notification.create(
       activity_id: self.activity,
       user_id: @user,
       comment_id: self,
       read: false
      )
  end
end

_create_notifications.rb

class CreateNotifications < ActiveRecord::Migration
  def change
    create_table :notifications do |t|
      t.references :activity, index: true
      t.references :comment, index: true
      t.references :user, index: true
      t.boolean :read

      t.timestamps null: false
    end
    add_foreign_key :notifications, :activities
    add_foreign_key :notifications, :comments
    add_foreign_key :notifications, :users
  end
end

Answer 1

要确定activity所在的页面，您可以执行以下操作：

activity = Activity.find(notification.activity_id)
index    = Activity.order(created_at: :desc).index(activity)

以上内容将确定所有活动中index的{​​{1}}。

所以，假设你有85项活动。你每页有20个活动，所以在这种情况下你会有5页，对吗？好吧，让我们假设上面的activity返回42.要计算页码，你必须这样做（假设你有一个名为index的变量是20）：

per_page

你有page_number = (index / per_page.to_f).ceil 42。你需要除以每页活动的数量（需要成为一个浮动！），这样就是{ {1}}。这导致index。 20.0那你已经得到了你的页码，这就是3。

因此，要创建正确的分页路径，您现在可以执行此操作：

2.1

<强>更新

既然我们知道ceil未在activities_path(page: page_number) 上正确设置，我们可以解决这个问题（另请注意，activity_id也未设置）。将notification模型的最后一部分更改为：

comment_id

我在此处添加了两个验证，以确保Comment和... belongs_to :activity validates :activity_id, presence: true validates :user_id, presence: true private def create_notification Notification.create(activity_id: self.activity_id, user_id: self.user_id, comment_id: self.id, read: false) end 已设置。正如我在activity_id之前所说的那样。这是因为user_id仅在comment_id上分配，在id上，您只是将其设置为保存。因此，将save更改为create也可以设置after_create :create_notification。

应设置after_save :create_notification和comment_id。现在是下一部分。获取应添加到activity_id部分链接中的链接的正确页码。

将这些方法添加到comment_id班级：

_notification.html.erb

现在将Activity部分中的路径更改为：

def page_number
  (index / per_page.to_f).ceil
end

private

def index
  Activity.order(created_at: :desc).index self
end

注意：如果您在notifications/_notification.html.erb方法中遇到activities_path(page: notification.activity.page_number) 错误，则可能未在模型中设置值per_page（如this;基本上将page_number添加到per_page）

下方的模型中

如果您决定这样做，可以删除self.per_page = 20中的class Activity < ActiveRecord::Base部分。如果没有，只需将, :per_page => 20替换为ActivitiesController或per_page.to_f。

另外，请删除之前已注释掉的20.to_f中的3行，以确定是否设置了20.0。你不再需要它们了，因为我们把它们放在了NotificationsController类中。