How do I use user_helper method globally throughout the app views? - railstutorial.org

Question

I finished chapter 8 on Michael Hartl's Rails Tutorial, so I have the app set up to sign users up & sign in and out.
What I am trying to do user a User Helper method inside the application.html.erb (or more specifically inside a _header.html.erb partial).
I want to use the gravatar_for method (Defined in the user_helper.rb) to show the user's gravatar picture and users name instead of having the word "Account" with the drop down.
module UsersHelper
# Returns the Gravatar for the given user.
def gravatar_for(user, options = { size: 150})
gravatar_id = Digest::MD5::hexdigest(user.email.downcase)
size = options[:size]
gravatar_url = "http://gravatar.com/avatar/#{gravatar_id}?s=#{size}"
image_tag(gravatar_url, alt: user.name, class: "gravatar")
end
end
On the show.html.erb page I have the following code
<% provide(:title, #user.name ) %>
<div class="row">
<aside class="span6">
<section>
<h1>
<%= gravatar_for #user %>
<%= #user.name %>
</h1>
</section>
</aside>
</div>
And that shows the user's gravatar and name on their profile page. So what I tried to do was add those same methods to the header partial like so;
<% if signed_in? %>
<li id="fat-menu" class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">
<span id="small">
<%= gravatar_for #user %><%= #user.name %><b class="caret"></b>
</span>
</a>
<ul class="dropdown-menu">
<li><%= link_to "Profile", current_user %></li>
<li><%= link_to "Settings", '#' %></li>
<li class="divider"></li>
<li><%= link_to "Sign out", signout_path, method: "delete" %></li>
</ul>
</li>
<% else %>
<li id="cta"><%= link_to "+ Sign up", signup_path %></li>
<li><%= link_to "Sign in", signin_path %></li>
<% end %>
And that code shows up completely fine on the show.html.erb page, which I am assuming is because its the show action on the Users controller. But when I try to click to the home page or really any other page outside of the Users View then I get the error
NoMethodError in Pages#about
undefined method `email' for nil:NilClass
So I guess my question is how do I make the gravatar for method and the #user.name available to all the views throughout the application. I feel as if the answer should be fairly simple, but i'm pretty new to rails, so any help would be greatly appreciated!

Answer 1

Put the method in the ApplicationHelper instead of the UserHelper. Here is an example of something similar I did in my own app: https://github.com/NatashaTheRobot/tinysale/blob/master/app/helpers/application_helper.rb