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of 65What is Ruby on Rails and what is the MVC pattern?
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Ruby on Rails is a server-side web application framework written in Ruby that follows the Model-View-Controller (MVC) architectural pattern. MVC separates the application into three interconnected components:
- Model: Manages data and business logic, interacts with the database
- View: Handles presentation layer and user interface
- Controller: Processes requests, coordinates between Model and View
Rails emphasizes convention over configuration and DRY (Don't Repeat Yourself) principles, making development faster and more maintainable.
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Explain the Rails directory structure and purpose of key folders
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The main Rails directories include:
app/- Core application code (models, views, controllers, helpers, assets)config/- Application configuration, routes, database settingsdb/- Database schema, migrations, seedslib/- Extended modules and custom librariespublic/- Static files directly served by web servertest/orspec/- Test filesvendor/- Third-party codeGemfile- Gem dependencies specification
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What is the difference between symbols and strings in Ruby, and why does Rails prefer symbols for hash keys?
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Symbols are immutable and stored in memory only once, while strings create new objects each time. Rails prefers symbols because:
- Memory efficiency - symbols are stored once
- Performance - faster comparison operations
- Immutability - prevents accidental modification
# Symbol - same object_id
:name.object_id == :name.object_id # true
# String - different objects
"name".object_id == "name".object_id # false
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What is the Rails Convention over Configuration principle?
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Convention over Configuration means Rails makes assumptions about what you want to do and how you'll do it, rather than requiring you to specify every detail. Examples include:
- Model
Usermaps to database tableusers - Controller
UsersControllerhandles/usersroutes - Primary keys are named
id - Foreign keys follow pattern
table_id
This reduces the amount of code developers need to write and maintains consistency across projects.
ActiveRecord & Database
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Explain database migrations in Rails
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Migrations are Ruby classes that allow you to evolve your database schema over time in a consistent way. They provide:
- Version control for database schema
- Team collaboration on schema changes
- Database-agnostic schema modifications
- Rollback capabilities
class CreateUsers < ActiveRecord::Migration[7.0]
def change
create_table :users do |t|
t.string :email
t.timestamps
end
end
end
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What's the difference between `find`, `find_by`, and `where`?
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- find: Finds by primary key, raises ActiveRecord::RecordNotFound if not found
- find_by: Finds first record matching conditions, returns nil if not found
- where: Returns ActiveRecord::Relation with all matching records
User.find(1) # Raises error if not found
User.find_by(email: "a@b.com") # Returns nil if not found
User.where(active: true) # Returns Relation (chainable)
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What is the difference between `render` and `redirect_to`?
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- render: Renders a view template without a new HTTP request, maintains instance variables
- redirect_to: Sends HTTP redirect response, triggers new request, loses instance variables
def create
@user = User.new(user_params)
if @user.save
redirect_to @user # New request to show action
else
render :new # Renders new template with @user errors
end
end
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What are the differences between `rails console` options?
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Rails console options:
rails consoleorrails c: Standard consolerails console --sandbox: Rolls back changes on exitrails console production: Production environment consolerails dbconsoleorrails db: Direct database console
# Sandbox mode - all changes rolled back
rails console --sandbox
# Production console
RAILS_ENV=production rails console
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How does Rails handle different environments and what are they used for?
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Rails provides three default environments:
- Development: Reloading, verbose errors, debugging tools
- Test: Isolated testing, fixtures, transaction rollback
- Production: Optimized performance, caching, error monitoring
# Check current environment
Rails.env.development? # true/false
Rails.env # "development"
# Environment-specific code
if Rails.env.production?
# Production-only code
end
# Custom environments
RAILS_ENV=staging rails server
Each environment has its own configuration file in config/environments/ and database configuration.
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What is ActiveRecord and how does it implement the Active Record pattern?
Explain different types of associations in Rails
What is the N+1 query problem and how do you solve it?
What are scopes in ActiveRecord and how do you use them?
Explain callbacks in ActiveRecord and their order of execution
What are validations and how do custom validations work?
What are strong parameters and why are they important?
Explain the Rails routing system and RESTful routes
What are before_action filters and how do they work?
How do you handle different response formats in Rails controllers?
Explain nested routes and when to use them
How does Rails protect against CSRF attacks?
What is SQL injection and how does Rails prevent it?
Explain Rails session management and storage options
How do you implement authentication in Rails?
What is lazy loading vs eager loading in ActiveRecord?
What is Rails cache store and what are the available options?
Explain the Rails asset pipeline and its benefits
What testing frameworks does Rails support and what are the differences?
What are fixtures and factories in Rails testing?
How do you test Rails APIs?
What is the difference between stubs and mocks in testing?
What is ActiveJob and what adapters does it support?
When should you use background jobs in Rails?
How do you build RESTful APIs in Rails?
What serializers can you use for JSON APIs in Rails?
How do you implement API versioning in Rails?
What are concerns in Rails and when should you use them?
What are service objects and when should you use them?
What are Rails generators and how do you create custom ones?
What are the key considerations for deploying Rails applications?
How do you manage environment-specific configuration in Rails?
How do you implement rate limiting in Rails?
What is Turbo/Stimulus and how does it work with Rails?
How do you handle file uploads in Rails?
How do you debug Rails applications effectively?
Explain the request/response cycle in Rails
How do you implement internationalization (i18n) in Rails?
What's the difference between `includes`, `preload`, and `eager_load`?
Explain optimistic vs pessimistic locking in Rails
What are the security headers Rails provides and how do you configure them?
Explain different caching strategies in Rails
How do you optimize database queries in Rails?
How do you handle job failures and retries?
How do you implement API authentication?
Explain Rails engines and when to use them
What is ActionCable and how does it work?
Explain the Rails autoloading mechanism
What is the difference between `delegate` and `forwardable`?
How do you handle multi-tenancy in Rails?
Explain monkey patching in Rails and its risks
What is the difference between Webpacker, Sprockets, and Import Maps?
Explain database connection pooling in Rails
What are the benefits and implementation of database sharding in Rails?
What is Rack middleware and how do you create custom middleware?
What are the best practices for Rails application security?
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