Showing .../app/views/campaigns/show.html.erb where line #1 raised:

undefined method `name' for nil:NilClass

<h2><%= @campaign.name %></h2>
<p>
  Created by: <%= @campaign.user.email %> <%= time_ago_in_words(@campaign.created_at) %> ago.
</p>
<h5>Website: <%= @campaign.website %></h5>

resources :campaigns do
    resources :targets
  end

  get "campaigns/building" => "campaigns#building", :as => :campaigns_building

class CampaignsController < ApplicationController
  before_action :find_campaign, only: [:show, :edit, :update, :destroy]
  before_action :authenticate_user!
  def show
  end

  def building
  end
...

<h2><%= @campaign.name %></h2>
<p>
  Created by: <%= @campaign.user.email %> <%= time_ago_in_words(@campaign.created_at) %> ago.
</p>
<h5>Website: <%= @campaign.website %></h5>