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Editorial Team
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Asked: 2026-06-11T15:56:52+00:00

I have a database of objects (tools) in my Ruby on Rails project. When

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I have a database of objects (tools) in my Ruby on Rails project. When I use “rails dbconsole” and

select * from tools;

it returns a whole list of tool objects. But when I try to view the following page, it gives me an error.

Page:

 <!DOCTYPE html>
<html lang="en">


<%= stylesheet_link_tag "tools", :media => "all" %>
<body>
<%= @tools.each do |tool| %>
 <%= link_to(tool(image_tag.image_url)) %>
 <% end %>

</body>
</html>

Error: 

undefined method `each' for nil:NilClass

When I change the code to add an if statement against nil objects, the page works (without displaying any tools).

<% if @tools.nil? %>
<% else %>
  <%= @tools.each do |tool| %>
    <%= link_to(tool(image_tag.image_url)) %>
    <% end %>
<% end %>

So it seems like @tools doesn’t have any values in it, but when I look at it in the dbconsole, there are tools there. I can’t figure this out, and I’ve spent the past few days googling for answers, so any and all ideas would be welcome!

EDIT: Added tools_controller.rb

class ToolsController < ApplicationController
before_filter :check_authentication
def check_authentication
  unless session[:user_id]
    session[:intended_action] = action_name
    session[:intended_controller] = controller_name
    redirect_to new_session_url
  end
end

  def new
    @tool = Tool.new
    respond_to do |format|
      format.html # new.html.erb
      format.json { render :json => @tool }
    end
  end

 def show
 end

 def index
    @tools = Tool.all
  end

  # GET /tools/1/edit
  def edit
    @tool = Tool.find(params[:id])
  end

  # POST /tools
  # POST /tools.json
 def create
    @tool = Tool.new(params[:tool])
    respond_to do |format|
      if @tool.save
        format.html { redirect_to @tool, :notice => 'tool was successfully created.' }
        format.json { render :json => @tool, :status => :created, :location => @tool }
      else
        format.html { render :action => "new" }
        format.json { render :json => @tool.errors, :status => :unprocessable_entity }
      end
    end
  end
end
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1 Answer

  1. Editorial Team

    In order for the @tools variable to be accessible from your view, you need to declare it in your controller, like this:

    @tools = Tool.all

    If you want it to be only accessible from one page, just declare it in the according method.

    Here is an example, assuming you want to make the variable available for your home/index page:

    class HomeController < ApplicationController

  def index
     @tools = Tool.all

    respond_to do |format|
      format.html # index.html.erb
    end
  end
end

    If you want it to be accessible in all your pages, you can declare it in the before_filter method of your ApplicationController.

    Here is how to do this:

    class ApplicationController < ActionController::Base
  protect_from_forgery
  before_filter :load_variables

  # Load variables to be used everywhere
  def load_variables
    @tools = Tool.all
  end
end
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