Select enum from form to set role

Question

Ruby on Rails 4.1

I am using Devise with enum role. It currently sets a defualt role when the User is created. I want to add a field to the form that creates Users to set the enum role.

I read this but it doesn't say how to utilize the new roles.

This is the User class

devise :database_authenticatable, :registerable, :confirmable,
     :recoverable, :rememberable, :trackable, :validatable
enum role: [:user, :vip, :admin, :developer, :marketing, :support, :translator]
after_initialize :set_default_role, :if => :new_record?

def set_default_role
  self.role ||= :user
end

This is the part of the form where I am trying to have a select to pick an enum role:

<div class="form-group">
  <%= f.collection_select :role, User.roles, :id, :enum, {prompt: "Select a role"}, {class: "form-control input-lg"} %>
</div>

The error:

NoMethodError - undefined method `enum' for ["user", 0]:Array:
actionview (4.1.1) lib/action_view/helpers/form_options_helper.rb:761:in `value_for_collection'

I have never used enum before and the documentation is not proving helpful. How do I make the enum options show?

Answer 1

To start, enum is not the name of an attribute. The name of the attribute is role.

Take a look at the rails-devise-pundit example application, specifically the file app/views/users/_user.html.erb which is a partial that creates a form to allow the administrator to change a user's role. I doubt you want to use a collection_select for helper (that is suitable if you have a separate Role model). Instead, an ordinary select form helper will work.

Here's a simple example that hardcodes the role options:

<%= f.select(:role, [['User', 'user'], ['Vip', 'vip'], ['Admin', 'admin']]) %>

Here is a better example that avoids hardcoding the roles in the form:

<%= f.select(:role, User.roles.keys.map {|role| [role.titleize,role]}) %>

The statement obtains an array of roles from the User model and constructs an array of key-value pairs using the map method.

Answer 2

Since you are using Rails 4 or higher, enums are even less complicated.

Given the following enum:

enum role: {
  admin: 1
}

Enums expect the HTML option attribute value to be the enum key:

<option value="admin"> <!-- As opposed to: <option value="1"> -->

Knowing this, you can pass in the enum keys.

<%= f.select :role, User.roles.keys, {}, class: 'user-roles-select' %>

Then using CSS you can modify the appearance.

.user-roles-select option {
  text-transform: capitalize;
}