Generate Options straight from the Model for using them with html select options.

select_options.rb

module SelectOptions

  extend ActiveSupport::Concern

  FIRST_OPTION = %w[All default].freeze

  class_methods do
    def enum_select_options(enum_name)
      define_singleton_method "#{enum_name}_select_options" do |method_params = { header: true }|
        map = send(enum_name.to_s.pluralize).map { |k, _| [k.humanize, k]}
        map.unshift(FIRST_OPTION) if method_params[:header]
        map
      end
    end

    def define_select_options(method_name, params = {})
      define_singleton_method method_name do |method_params = { header: true, condition_params: nil }|
        query = params[:conditions]&.call(*method_params[:condition_params]) || all
        map = query.map { |cp| [cp.send(params[:text]), cp.send(params[:value])] }
        map.unshift(FIRST_OPTION) if method_params[:header]
        map
      end
    end
  end

end

# MODEL USAGE

class User
  
  include SelectOptions
  
  define_select_options :select_options, value: :id, text: :full_name, conditions: -> { ascending.enabled }
  
end

# EXAMPLE

def user_select_options
  User.select_options
end

# MODEL USAGE WITH PARAMETER ON CONDITIONS

class User
  
  include SelectOptions
  
  define_select_options :select_options, value: :id, text: :full_name, conditions: lambda { |teacher_id|
    joins(:courses).where(courses: { teacher_id: teacher_id } ).order('users.first_name asc')
  }
  
end

# EXAMPLE

def user_select_options
  User.select_options(condition_params: 5)
end


# MODEL USAGE FOR ENUMS

class User
  
  include SelectOptions
  
  enum status: %i[
    pending enrolled graduated completed
  ]
  
  enum_select_options :status
  
end

# EXAMPLE

def user_status_options
  User.status_select_options
end