Route constraints in Ruby on Rails - Mini Project: Build & Apply

Using Route Constraints in Rails

📖 Scenario: You are building a simple Rails web app that serves different pages based on user roles. You want to restrict access to certain routes so only users with specific roles can visit them.

🎯 Goal: Learn how to use route constraints in Rails to control access to routes based on user roles.

📋 What You'll Learn

Create a custom route constraint class

Add a configuration variable for allowed roles

Use the constraint in the routes file to restrict access

Complete the routes setup with the constraint applied

💡 Why This Matters

🌍 Real World

Route constraints help control access to parts of a web app based on user roles or other conditions, improving security and user experience.

💼 Career

Understanding route constraints is important for Rails developers to implement role-based access control and customize routing behavior.

1

Create a custom route constraint class

Create a Ruby class called UserRoleConstraint with a method matches? that takes a request parameter and returns true if the user role is 'admin'.

Ruby on Rails

# Your code here

Need a hint?

Define a class with a matches? method that checks if request.params[:role] equals 'admin'.

2

Add a configuration variable for allowed roles

Create a variable called allowed_roles and set it to an array containing the string 'admin' and 'manager'.

Ruby on Rails

class UserRoleConstraint
  def matches?(request)
    request.params[:role] == 'admin'
  end
end

# Your code here

Need a hint?

Use an array allowed_roles and check if request.params[:role] is included in it.

3

Use the constraint in the routes file

In the config/routes.rb file, add a route get '/dashboard' that routes to dashboard#index and uses the constraint UserRoleConstraint.new.

Ruby on Rails

class UserRoleConstraint
  def matches?(request)
    allowed_roles = ['admin', 'manager']
    allowed_roles.include?(request.params[:role])
  end
end

Rails.application.routes.draw do
  # Your code here
end

Need a hint?

Use get '/dashboard', to: 'dashboard#index', constraints: UserRoleConstraint.new inside the routes.draw block.

4

Complete the routes setup with the constraint applied

Add a root route root to: 'home#index' without constraints below the constrained route in config/routes.rb.

Ruby on Rails

class UserRoleConstraint
  def matches?(request)
    allowed_roles = ['admin', 'manager']
    allowed_roles.include?(request.params[:role])
  end
end

Rails.application.routes.draw do
  get '/dashboard', to: 'dashboard#index', constraints: UserRoleConstraint.new
  # Your code here
end

Need a hint?

Add root to: 'home#index' inside the routes.draw block after the constrained route.