Using dynamic instance variable in partial Rails 4

Question

I am stumped. I want to use an instance variable in my navbar to show dynamic content from a table.

In terms of file structure, within my Views, I have a /layouts folder. Within that folder, there is a _header.html.erb for the navbar that is placed in the view through <%= render 'layouts/header' %> in application.html.erb file.

Now here's where it gets sticky. In my navbar, I have a set of links. I want it to render an instance variable as a link (the text it shows, not the path), so I am writing:

 <ul class="nav navbar-nav navbar-right">
      <li><%= link_to "About", about_path %></li> 
          <li><%= link_to "Settings", edit_user_registration_path %></li>
           <li><%= link_to "My Example", myexample_path %></li> 
           <li><%= link_to @example, stack_path %></li>
  </ul>

I have tried doing two different things with the instance variable.

So I need to define @example = Stack.where(user_id: current_user.id).pluck(:points) to return a number that I want to place in that navbar. I have tried putting that instance in the Application Controller and by making a Layouts Controller and placing it there in def index.

Therefore, my question is: to create an instance variable to be read by this _layouts.html.erb file, which controller is appropriate to use?

As a final note, whether I add it to the Application Controller or Layouts Controller, it simply doesn't render. If I remove the @example instance and instead put static text, it will add it to the navbar. So this seems to be my issue.

<%= render 'header' %> try this or put header.htm.erb in shared directory and use this <%= render 'shared/header' %> — uzaif
– uzaif, Commented Apr 12, 2016 at 4:17
@uzaif - Just to be clear, the layouts/_header.html.erb is actually rendering, all except the dynamic content. I am confused as to which controller needs to be used to connect it to the header file if I want to store an instance variable. Does your solution address that? — darkginger
– darkginger, Commented Apr 12, 2016 at 4:24
write method in application controller and access it with before filter return the variable which you need in header.html.erb — uzaif
– uzaif, Commented Apr 12, 2016 at 4:27

uzaif · Accepted Answer · 2016-04-12 04:37:42Z

2

in application controller

class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
  before_filter :add_header_text

  def add_header_text
   @menu = Menu.all 
  end

end

Now @menu instance variable is available in header partial

answered Apr 12, 2016 at 4:37

uzaif

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