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104 lines
4.8 KiB
Markdown
104 lines
4.8 KiB
Markdown
# Welcome to Rails
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## What's Rails
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Rails is a web-application framework that includes everything needed to
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create database-backed web applications according to the
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[Model-View-Controller (MVC)](http://en.wikipedia.org/wiki/Model-view-controller)
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pattern.
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Understanding the MVC pattern is key to understanding Rails. MVC divides your
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application into three layers: Model, View, and Controller, each with a specific responsibility.
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## Model layer
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The _**Model layer**_ represents the domain model (such as Account, Product,
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Person, Post, etc.) and encapsulates the business logic specific to
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your application. In Rails, database-backed model classes are derived from
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`ActiveRecord::Base`. [Active Record](activerecord/README.rdoc) allows you to present the data from
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database rows as objects and embellish these data objects with business logic
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methods.
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Although most Rails models are backed by a database, models can also be ordinary
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Ruby classes, or Ruby classes that implement a set of interfaces as provided by
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the [Active Model](activemodel/README.rdoc) module.
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## Controller layer
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The _**Controller layer**_ is responsible for handling incoming HTTP requests and
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providing a suitable response. Usually this means returning HTML, but Rails controllers
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can also generate XML, JSON, PDFs, mobile-specific views, and more. Controllers load and
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manipulate models, and render view templates in order to generate the appropriate HTTP response.
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In Rails, incoming requests are routed by Action Dispatch to an appropriate controller, and
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controller classes are derived from `ActionController::Base`. Action Dispatch and Action Controller
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are bundled together in [Action Pack](actionpack/README.rdoc).
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## View layer
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The _**View layer**_ is composed of "templates" that are responsible for providing
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appropriate representations of your application's resources. Templates can
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come in a variety of formats, but most view templates are HTML with embedded
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Ruby code (ERB files). Views are typically rendered to generate a controller response,
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or to generate the body of an email. In Rails, View generation is handled by [Action View](actionview/README.rdoc).
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## Frameworks and libraries
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[Active Record](activerecord/README.rdoc), [Active Model](activemodel/README.rdoc), [Action Pack](actionpack/README.rdoc), and [Action View](actionview/README.rdoc) can each be used independently outside Rails.
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In addition to that, Rails also comes with [Action Mailer](actionmailer/README.rdoc), a library
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to generate and send emails; [Active Job](activejob/README.md), a
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framework for declaring jobs and making them run on a variety of queueing
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backends; [Action Cable](actioncable/README.md), a framework to
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integrate WebSockets with a Rails application; [Active Storage](activestorage/README.md), a library to attach cloud
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and local files to Rails applications;
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and [Active Support](activesupport/README.rdoc), a collection
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of utility classes and standard library extensions that are useful for Rails,
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and may also be used independently outside Rails.
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## Getting Started
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1. Install Rails at the command prompt if you haven't yet:
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$ gem install rails
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2. At the command prompt, create a new Rails application:
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$ rails new myapp
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where "myapp" is the application name.
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3. Change directory to `myapp` and start the web server:
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$ cd myapp
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$ rails server
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Run with `--help` or `-h` for options.
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4. Go to `http://localhost:3000` and you'll see:
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"Yay! You’re on Rails!"
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5. Follow the guidelines to start developing your application. You may find
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the following resources handy:
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* [Getting Started with Rails](http://guides.rubyonrails.org/getting_started.html)
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* [Ruby on Rails Guides](http://guides.rubyonrails.org)
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* [The API Documentation](http://api.rubyonrails.org)
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* [Ruby on Rails Tutorial](https://www.railstutorial.org/book)
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## Contributing
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[](https://www.codetriage.com/rails/rails)
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We encourage you to contribute to Ruby on Rails! Please check out the
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[Contributing to Ruby on Rails guide](http://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html) for guidelines about how to proceed. [Join us!](http://contributors.rubyonrails.org)
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Trying to report a possible security vulnerability in Rails? Please
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check out our [security policy](http://rubyonrails.org/security/) for
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guidelines about how to proceed.
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Everyone interacting in Rails and its sub-projects' codebases, issue trackers, chat rooms, and mailing lists is expected to follow the Rails [code of conduct](http://rubyonrails.org/conduct/).
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## Code Status
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[](https://travis-ci.org/rails/rails)
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## License
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Ruby on Rails is released under the [MIT License](https://opensource.org/licenses/MIT).
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