Dynamic Rails routes based on database models

Question

So I\'m building a Rails site that needs routes based on two different types

I have a Language model and a Category model

So I need to be able to go to a la

Answer 1

There is a nice solution to that problem using routes constraints.

Using routes constraints

As the rails routing guide suggests, you could define routes constraints in a way that they check if a path belongs to a language or a category.

# config/routes.rb
# ...
get ':language', to: 'top_voted#language', constraints: lambda { |request| Language.where(name: request[:language]).any? }
get ':category', to: 'top_voted#category', constraints: lambda { |request| Category.where(name: request[:category]).any? }

The order defines the priority. In the above example, if a language and a category have the same name, the language wins as its route is defined above the category route.

Using a Permalink model

If you want to make sure, all paths are uniqe, an easy way would be to define a Permalink model and using a validation there.

Generate the database table: rails generate model Permalink path:string reference_type:string reference_id:integer && rails db:migrate

And define the validation in the model:

class Permalink < ApplicationRecord
  belongs_to :reference, polymorphic: true
  validates :path, presence: true, uniqueness: true

end

And associate it with the other object types:

class Language < ApplicationRecord
  has_many :permalinks, as: :reference, dependent: :destroy

end

This also allows you to define several permalink paths for a record.

rails_category.permalinks.create path: 'rails'
rails_category.permalinks.create path: 'ruby-on-rails'

With this solution, the routes file has to look like this:

# config/routes.rb
# ...
get ':language', to: 'top_voted#language', constraints: lambda { |request| Permalink.where(reference_type: 'Language', path: request[:language]).any? }
get ':category', to: 'top_voted#category', constraints: lambda { |request| Permalink.where(reference_type: 'Category', path: request[:category]).any? }

And, as a side note for other users using the cancan gem and load_and_authorize_resource in the controller: You have to load the record by permalink before calling load_and_authorize_resource:

class Category < ApplicationRecord
  before_action :find_resource_by_permalink, only: :show
  load_and_authorize_resource

  private

  def find_resource_by_permalink
    @category ||= Permalink.find_by(path: params[:category]).try(:reference)
  end
end