Use one action for multiple models

Question

I have about 5 models that behave very similarly. In fact, I'd like them to share an action for displaying them. For example, for models Car, Truck, Van I want to have a definition like:

[Car, Truck, Van].each do |Model|
  action_for Model do #I made this up to show what I mean
    def index
      @model = Model.all
      @model_names = @model.map(&:name).join(', ')
    end
  end
end

How would I do this so I'm not defining the same action in multiple controllers? (Which isn't very DRY) Would it be in the application_controller? And if it's not too much to ask, how could I do this so they also share the view?

UPDATE

It would be preferred if this can be outside the individual controllers. If I can get this to work right, I'd like to not even have to generate the individual controllers.

You might be interested in peeping or using [Inheritable Resources](https://github.com/josevalim/inherited_resources) by José Valim. ActiveAdmin uses it for default RESTful actions. — coreyward, Mar 11 '12 at 04:52

score 4 · Accepted Answer · edited May 23 '17 at 12:21

4

Would something like this work for you?

module Display
  def index
    m = self.class.to_s.chomp('Controller').classify.constantize
    @model = m.all
    @model_names = @model.map(&:name).join(', ')
  end
end

In the controllers:

class CarsController < ApplicationController
  include Display 
end

class TrucksController < ApplicationController
  include Display 
end

class VansController < ApplicationController
  include Display 
end

Edit: an attempt to do this without individual controllers

class DisplaysController < ApplicationController
  def index
    @model = params[:model].constantize.all
    @model_names = @model.map(&:name).join(', ')
  end
end

routes.rb

match "display" => "display#index", :as => :display

In a view

link_to "Display Cars", display_path(:model => "Car")
link_to "Display Trucks", display_path(:model => "Truck")
link_to "Display Vans", display_path(:model => "Van")

Note: If you've heard of extend for modules and are wondering why/when to use include vs extend, see What is the difference between include and extend in Ruby? (basically include is for instances, extend for class methods).

edited May 23 '17 at 12:21

Community

1
1

answered Mar 11 '12 at 04:32

Kyle

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Very good! I'm going to hold out for a bit though if you don't mind. If I can find the answer I'm thinking of, I shouldn't even need controllers for each of the models – Kyle Macey Mar 11 '12 at 04:42
@KyleMacey - I think my edit will work for you but I have not tested. Let me know if you try it and it doesn't work so I can remove it. – Kyle Mar 11 '12 at 04:58
Rather than using `Object.const_get` you can use `constantize`. You can shorten that whole line up to `m = name.chomp('Controller').classify.constantize`. – coreyward Mar 11 '12 at 05:05
1

I thought it might be useful to note when to use `include` vs. `extend` which people may well have heard of, so I added that at the bottom of this answer (above) as a note. – Michael Durrant Mar 11 '12 at 05:25
The code `self.class.to_s.chomp('Controller')` can be replaced with `controller_name` – Harish Shetty Mar 11 '12 at 18:09
I might have to go with your original method. I don't want to sacrifice clean routing on behalf of my own laziness. Having `/vans` and `/trucks` seems to make the most sense to me. Thanks for great answers! – Kyle Macey Mar 12 '12 at 00:46
@KyleMacey did you settle on a method? I'm curious. – Kyle Mar 14 '12 at 03:44
@Kyle Ended up writing a custom generation file to regenerate and populate the controllers when I want to make changes. I couldn't get the Module to work right, and I need pretty routes. I'll post as an answer so you can see. – Kyle Macey Mar 14 '12 at 04:25

Use one action for multiple models

1 Answers1