Ruby on Rails - Paginating Comments

Question

I have created an application where Users can create Projects and make Comments on these Projects. Right now, I have ability for users to make comments on each Project page.

Question: Based on my code below, will I be able to use will_paginate? I do have the gem installed, so, if so, how would I integrate it into my code below? If not, what would I need to do to build in pagination?

comment.rb

class Comment < ActiveRecord::Base
  attr_accessible :content, :project_id, :user_id
  validates :content, presence: true

  belongs_to :project
  belongs_to :user

  scope :newest, order("created_at desc")
end

comments_controller.rb

class CommentsController < ApplicationController
  before_filter :authenticate_user! 

  def create
    project = Project.find(params[:project_id])
    @comment = project.comments.create!(params[:comment])
    redirect_to project_path(project)
  end
end

projects/show.html.erb

        <!-- Add Comments -->

          <% if signed_in? %>
            <p class="comment_header">Add Comment:</p>

            <span class="comment">
                <%= form_for([@project, @project.comments.build]) do |f| %>
                  <div class="field">
                    <%= f.text_area :content, :class => "span7", :rows => "3" %>
                  </div>

                  <%= f.hidden_field :user_id, :value => current_user.id %>

                  <div class="actions">
                    <%= f.submit "Add Comment", :class => "btn btn-header" %>
                  </div>
                <% end %>
            </span>

          <% else %>

            <p class="comment_header"><%= link_to 'Sign in', new_user_session_path %> to post comments.</p> 

          <% end %>

          <!-- Show Comments -->
          <p class="comment_header">Comments:</p>

          <% if @project.comments.blank? %>     
            <p>No comments made yet for this project.</p>        
          <% else %>        
            <% @project.comments.newest.each do |comment| %>   
              <div class="comments">        
                <p><%= comment.content %></p>
                <span>By <%= link_to comment.user.name, comment.user %> <%= time_ago_in_words(comment.created_at) %> ago</span>
              </div>
            <% end %>       
          <% end %>
          <!-- end of comments section -->

Answer 1

Yes you can use will_paginate gem. This gem is just for get a number of rows with page number and you can specify number of elements per page. For exemple page 1 will give you element 1 to 30 page 2 31 to 60 .... After you have to implement the view

Answer 2

You can use will_paginate without any problems. Also you can look at kaminari which is more flexible.

Answer 3

you can call paginate methods before redirect

in you controller

  @comments = @project.comments.pagenate(page: params[:page]||1,per_page: 20)

and add the following to you template

  <%= will_paginate @comments %>

Answer 4

You haven't implemented will_paginate correctly. ( You can read about proper implementation in the documentation here. )

Simply put, you need to use something like @comments = @project.comments.paginate(page: params[:page]) in the controller for the index action and then iterate over @comments . Then doing will_paginate @comments should work correctly.

You can't just do the query ( will_paginate @user.comments.newest ) in the view because the paginate method returns a special object that handles pagination, unlike a normal ActiveRecord query.