Check if controller has a model in Rails

Question

In a dropdown I have fetched all controller classes with all their actions in another dropdown dynamically which are used for certain operations. There are some controllers that don't have any models like 'DashboardsController' don't have Dashboard model. It is just used to display dashboards.

So, basically I need to filter out controllers without models. I need a method to which I pass the controller class and returns me true/false .

def has_model?(controller_klass)
 # TODO
end 

Answer 1

You could try something like this, if you pass in the name of the controller as a string. This solution assumes that your models are using ActiveRecord prior to rails 5 where ApplicationRecord was used to define models; in that case just switch ActiveRecord::Base with ApplicationRecord . Also if you have models that are plain old ruby objects (POROs), then this wont work for them.

def has_model?(controller_klass)
  begin
    class_string = controller_klass.to_s.gsub('Controller', '').singularize
    class_instance = class_string.constantize.new
    return class_instance.class.ancestors.include? ActiveRecord::Base 
  rescue NameError => e
    return false
  end
end 

Answer 2

This method doesn't rely on exceptions, and works with input as Class or String. It should work for any Rails version :

def has_model?(controller_klass)
  all_models = ActiveRecord::Base.descendants.map(&:to_s)
  model_klass_string = controller_klass.to_s.sub(/Controller$/,'').singularize
  all_models.include?(model_klass_string)
end

Note : you need to set

config.eager_load = true

in

config/environments/development.rb

If you have non ActiveRecord models, you can ignore the previous note and use :

all_models = Dir[File.join(Rails.root,"app/models", "**","*.rb")].map{|f| File.basename(f,'.rb').camelize}