Nested routes in Ruby on Rails

Introduction

Nested routes help organize related web pages by showing their connection in the URL. They make it clear which pages belong inside others.

When you have a blog with posts and each post has comments.

When you want to show all orders for a specific customer.

When you have categories and each category has many products.

When you want URLs that reflect a parent-child relationship between resources.

Syntax

Ruby on Rails

Rails.application.routes.draw do
  resources :parents do
    resources :children
  end
end

This creates URLs like /parents/:parent_id/children/:id.

It helps keep related data grouped in the URL and controller.

Examples

This sets up routes so comments belong to posts, e.g., /posts/5/comments/2.

Ruby on Rails

resources :posts do
  resources :comments
end

This creates routes to access orders for a specific user, like /users/3/orders.

Ruby on Rails

resources :users do
  resources :orders
end

This nests products inside categories, showing their connection in URLs.

Ruby on Rails

resources :categories do
  resources :products
end

Sample Program

This code sets up nested routes where books belong to authors. URLs will look like /authors/1/books/2.

Ruby on Rails

Rails.application.routes.draw do
  resources :authors do
    resources :books
  end
end

Important Notes

Nested routes can get complex if you nest too deeply; keep nesting to 1 or 2 levels.

Use nested routes when the child resource always belongs to a parent resource.

You can access the parent ID in your controller to find related records.

Summary

Nested routes group related resources in URLs to show their connection.

They create clear, organized paths like /parents/:parent_id/children/:id.

Use them to keep your app structure logical and easy to understand.