Links to change ordering of a posts loop

问题

I'm trying to achieve links in my page that allow me to change the order that my posts display in. Similar to 'Recent', 'Hot' and 'Oldest' on Reddit.

I currently have by default

PostsController.rb

  def index
      @posts = Post.order('created_at DESC').all.paginate(page: params[:page],      per_page: 20)
  end

How would I go about adding links to a method to reverse the flow of posts to ASC or to display posts descending by a specific column on the model like views?

Jon

回答1:

I'd create some scopes and a method in the model to handle all the possibilities,

# Post.rb
scope :recent, -> { order(created_at: :desc) }
scope :hot,    -> { order(something: :desc) }
scope :oldest, -> { order(created_at: :asc) }

def self.sort_by(sort_param)
  case sort_param
  when 'recent'
    recent
  when 'hot'
    hot
  when 'oldest'
    oldest
  else
    all
  end
end

# controller
@posts = Post.sort_by(params[:order]).paginate(page: params[:page], per_page: 20)

Since I'm whitelisting, I don't really need to sanitize, any wrong param will return the default order.

If you want you could use #send and add method names to the whitelist array, but you need to make sure that the scope exists

def self.sort_by(sort_param)
  if %w(recent hot oldest).include? sort_param
    send sort_param
  else
    all
  end
end

回答2:

Use will_paginate gem in your app for Sorting in both directions and Paginate.Visit this link to implement it https://github.com/mislav/will_paginate.

回答3:

firstly you want to remove the all so that pagination works better.

 def index
      @posts = Post.order('created_at DESC').paginate(page: params[:page], per_page: 20)
 end

then you can use a variable to control the order. The important thing is to sanitise before passing to mysql.

 def index
      sort_by = ActiveRecord::Base::sanitize(params.permit(:sort_by))
      @posts = Post.order(sort_by).paginate(page: params[:page], per_page: 20)
 end

来源：https://stackoverflow.com/questions/29414349/links-to-change-ordering-of-a-posts-loop

标签

ruby-on-rails

ruby

ruby-on-rails-4

activerecord