Adding an admin role to a Rails app - ruby-on-rails

Question

I recently created a small rails app using Rails Composer with devise.
I then followed the guide to an admin attribute to the users table using this guide: https://github.com/plataformatec/devise/wiki/How-To:-Add-an-Admin-Role.
I'm struggling with this one thing:
in app/views/layouts/_nav_links_for_auth.html.erb, I have:
<% if user_signed_in? %>
<% if current_user.try(:admin?) %>
<li> <%= link_to 'Users', users_path %></li>
<% end %>
<% end %>
I have set the attribute to true for the user I'm logged in as - however, the statement if current_user.try(:admin?) above doesn't return true. I've doubled checked in the sqlite development database that the attribute is actually set to true, and it is.
So, I'm stuck. As best I can figure out, it doesn't know what actually is an "admin". In my user model, I have this (which was there by default):
class User < ActiveRecord::Base
enum role: [:user, :vip, :admin]
after_initialize :set_default_role, :if => :new_record?
...
end
I'd love some help with getting to this work. What do I need to do?

Answer 1

Why do you have an enum if you have an explicit admin attribute for your User model?
If you're using enum, you'd have a role attribute, which will give you methods such as admin?, or you need to have an explicit admin attribute - which you should have if you have fired the migration that you posted.
To clear up any potential confusion, enum is used if you have strict criteria for a column, and only wish your users to have certain values assigned to it. Roles is a great example:
#app/models/user.rb
class User < ActiveRecord::Base
enum role: [:admin, :user] #-> requires "role" column which will store either :admin (0) or :user (1) values
end
In your case, you have several issues.
Firstly, boolean columns create appropriate methods in your model for that column...
Having admin as a boolean column will give you #user.admin? method.
<%= content_tag :li, link_to('Users', users_path) if user_signed_in? && current_user.admin? %>
This is what you should use if you have the migration as you stated from the Devise link (IE you have an admin boolean column)
--
The second problem you have is that you're getting confused in your model.
IF you wanted to have a default role, and have potential roles defined with an enum, you'd want to use the following:
#app/models/user.rb
class User < ActiveRecord::Base
enum role: [:user, :vip, :admin]
# remove after_init callback
end
You'd set a default role by setting the role default value in your db:
$ rails g migration SetDefaultRole
#db/migrate/set_default_role_______.rb
class SetDefaultRole < ActiveRecord::Migration
def change
add_column :users, :role, :integer, default: 1
end
end
$ rails db:migrate #-> if you're using Rails 5
$ rake db:migrate #-> Rails 4+

Answer 2

You could use either the role enum or the admin attribute but not both.
The problem in your case is that the admin? method being called is the one that is defined by enum (which checks the role) rather than admin? method provided by activerecord for boolean columns.
So though your admin column is true, your role is not being set to admin (for reasons we can not investigate because your set_default_role implementation is not available).
I recommend adopting a role based system, investigating why the correct role is not being set and then getting rid of the admin column.