Dynamically direct routes for polymorphic associations - Ruby on Rails

Have you ever struggled with polymorphic associations? We all have, don’t worry.
Here’s an example of a polymorphic relationship.

	class Picture < ApplicationRecord
	belongs_to :imageable, polymorphic: true
	end
	class Employee < ApplicationRecord
	has_many :pictures, as: :imageable
	end
	class Product < ApplicationRecord
	has_many :pictures, as: :imageable
	end

view raw relationships.rb hosted with ❤ by GitHub

I’ve recently bumped into a problem where I had to list out all subjects (employees and products in this case) and when user interacted with one list item, it would redirect to that subject’s show page.

<table>

<thead>

<tr>

<th>Name</th>

</tr>

</thead>

<tbody>

<% @imageable.each do |imageable| %>

<tr>

<td>

<%= link_to imageable.name, ?????? %>

</td>

</tr>

<% end %>

</tbody>

</table>

view raw index.html.erb hosted with ❤ by GitHub

You can see the problem, right? The obvious solution here would be to check the type of imageable and set the path helper accordingly. But, there’s a slightly more advanced technique for this use-case: direct method.
In your routes.rb file simply add this:

direct(:imageable) { |imageable| route_for ("#{imageable.class.name.underscore}".to_sym, imageable) }

view raw routes.rb hosted with ❤ by GitHub

And now you can use imageable_path(imageable) as a path helper that will dynamically resolve to imageable’s show page.
Now our example above becomes:

<table>

<thead>

<tr>

<th>Name</th>

</tr>

</thead>

<tbody>

<% @imageable.each do |imageable| %>

<tr>

<td>

<%= link_to imageable.name, imageable_path(imageable) %>

</td>

</tr>

<% end %>

</tbody>

</table>

view raw index.html.erb hosted with ❤ by GitHub

Aaaand voilà, we’ve got a path helper that resolves to any imageable show page without the need to manually check for the type of imageable.