Rails: Query a model from a different view

Question

I have Post and SubCategory models that have a belongs_to and has_many relationship respectively.

In the Show view of Post, in addition to showing an individual Post, I need to run the index action of the SubCategory controller to show the current SubCategory and all of it's Post in a left Nav area.

What's the best way to go about this?

EDIT I was already utilizing Application Controller so I think this is the best route to go especially if I want to do the same thing in other views.

class ApplicationController < ActionController::Base
  protect_from_forgery
  before_filter :load_application_wide_varibales

  def load_application_wide_varibales

  def get_subcategory_and_post
    @sub_category = SubCategory.all
  end
end

class PostController < ActionController::Base
  before_filter :get_subcategory_and_post, only: [:show]

  def show
    @post = Post.find(params[:id])
    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @post }
  end
end

class SubCategoryController < ActionController::Base
    before_filter :get_subcategory_and_post
end

def current_user
  @current_user ||= User.find(session[:user_id]) if session[:user_id]
end
  helper_method :current_user
  end
end

Posts Show View

<% @sub_category.each do |subcat| %>
<div class="leftnav">
<h1 class="name"><%= subcat.name %></h1>
<% subcat.posts.each do |post| %>
<ul>
<li><%= link_to (post.name), post %></li>
</ul><% end %> 
</div>  

<% end %>
<div class="rightContent">
<p id="notice">
  <%= notice %>
</p>

<p>
  <b>Name:</b>
  <%= post.name %>
</p>

<p>
  <b>Content:</b>
  <%= post.content %>
</p>

</div>

Post model:

class Post < ActiveRecord::Base
  belongs_to :sub_category
  belongs_to :users
  validates :name, :content, :sub_category_id, :presence => true
  attr_accessible :content, :name, :sub_category_id
  after_save    :expire_post_all_cache
  after_destroy :expire_post_all_cache

def self.to_csv(options = {})
  CSV.generate(options) do |csv|
    csv << column_names
    all.each do |post|
      csv << post.attributes.values_at(*column_names)
    end
  end
end

def self.all_cached
  Rails.cache.fetch('Post.all') { all }
end

def expire_post_all_cache
  Rails.cache.delete('Post.all')
 end
end

SubCategory model:

class SubCategory < ActiveRecord::Base
  attr_accessible :name
  belongs_to :category
  has_many :posts
  validates :name, :category_id, :presence => true
end

Working Posts Show view:

<div class="leftnav">
<h1 class="name"><%= @post.sub_category.name %></h1>
<% @post.sub_category.posts.each do |post|%> 
<ul> 
<li><%= link_to (post.name), post %></li> 
    </ul><% end %>  
    </div> 

<div class="rightContent"> 
<p id="notice"><%= notice %></p> 

<p>
  <b>Name:</b>  
  <%= @post.name %>
</p>

<p>  
  <b>Content:</b>
  <%= @post.content %>
</p> 
</div> 

Answer 1

redirect_to your_controller_action_url and return

This will render another controllers action. However, this is contrary to how logic should be separated in controllers and typically considered to be a bad practice.

Your best bet would be to abstract the logic in the SubCategory controller to ApplicationController and then both the post and sub-category controllers can use it.

Here's an example with fake methods:

class ApplicationController < ActionController::Base
  def get_subcategory_and_post
    # Logic here
  end
end

class PostController < ActionController::Base
  before_filter :get_subcategory_and_post, only: [:show]

  def show
    # Logic here
  end
end

class SubCategoryController < ActionController::Base
  before_filter :get_subcategory_and_post
end

Answer 2

I would make a partial (something like _subcategory_list) that takes a subcategories collection and renders them. Then your Post view can call render(partial: 'subcategory/subcategory_list', locals: { subcategories: @post.subcategories }) and your SubCategory list view can do the same except pass in its @subcategories value.