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Ruby Basics

Introduction to RubyInstalling RubyRuby SyntaxRuby CommentsRuby VariablesRuby Data TypesRuby OperatorsRuby ConstantsRuby OutputRuby InputRuby String Interpolation

Control Structures

Ruby If-Else StatementsRuby Case StatementsRuby Unless StatementRuby While LoopsRuby For LoopsRuby Each IteratorRuby Break and NextRuby Redo and Retry

Ruby Methods

Defining Ruby MethodsRuby Method ArgumentsRuby Default ArgumentsRuby Keyword ArgumentsRuby Variable ArgumentsRuby Return ValuesRuby Method Aliases

Ruby Collections

Ruby ArraysRuby Array MethodsRuby HashesRuby Hash MethodsRuby RangesRuby Sets

Ruby OOP

Ruby ClassesRuby ObjectsRuby InheritanceRuby ModulesRuby MixinsRuby EncapsulationRuby PolymorphismRuby Method OverridingRuby Class VariablesRuby Instance VariablesRuby Getters and SettersRuby attr_* Methods

Ruby Advanced Concepts

Ruby BlocksRuby ProcsRuby LambdasRuby ClosuresRuby MetaprogrammingRuby ReflectionRuby Dynamic Method CreationRuby Singleton ClassesRuby Method MissingRuby Symbols

Ruby Exception Handling

Ruby Begin-Rescue-EndRuby Raise ExceptionsRuby Custom ExceptionsRuby Ensure ClauseRuby Retry Statement

Ruby File I/O

Ruby File Open and CloseRuby File Read OperationsRuby File Write OperationsRuby File ModesRuby Directory Operations

Ruby Modules and Gems

Ruby Module CreationRuby Module InclusionRuby NamespacesRuby Gem BasicsRuby Gem InstallationRuby Bundler

Ruby Testing

Ruby Unit TestingRuby Test::Unit FrameworkRuby RSpec BasicsRuby Mocking and Stubbing

Ruby Concurrency

Ruby ThreadsRuby FibersRuby GIL (Global Interpreter Lock)Ruby Parallel Processing

Ruby and the Web

Ruby CGI ProgrammingRuby ERB TemplatesRuby and HTTPRuby JSON ParsingRuby XML Parsing

Ruby Performance

Ruby ProfilingRuby BenchmarkingRuby Memory ManagementRuby Garbage Collection

Ruby Best Practices

Ruby Code Style GuideRuby Naming ConventionsRuby Design PatternsRuby Refactoring Techniques

Ruby ERB Templates

ERB (Embedded Ruby) is a powerful templating system in Ruby that allows you to embed Ruby code within HTML or other text documents. It's widely used for generating dynamic content in web applications, particularly with frameworks like Ruby on Rails.

What are ERB Templates?

ERB templates combine plain text with Ruby code snippets, enabling developers to create dynamic content easily. These templates are processed by the ERB library, which evaluates the embedded Ruby code and replaces it with the resulting output.

Basic Syntax

ERB uses special tags to embed Ruby code within a template:

  • <%= %> - Evaluates Ruby code and outputs the result
  • <% %> - Executes Ruby code without outputting the result
  • <%# %> - Comments (not executed or output)

Example Usage

Here's a simple example of an ERB template:


<!-- greeting.erb -->
<h1>Hello, <%= name %>!</h1>
<p>Today is <%= Time.now.strftime("%A, %B %d, %Y") %>.</p>
<% if logged_in? %>
    <p>Welcome back!</p>
<% else %>
    <p>Please log in.</p>
<% end %>

To render this template in Ruby:


require 'erb'

name = "Alice"
logged_in = true

template = File.read('greeting.erb')
renderer = ERB.new(template)
result = renderer.result(binding)

puts result

Common Use Cases

ERB templates are frequently used in various scenarios:

  • Generating HTML pages in web applications
  • Creating email templates
  • Producing configuration files
  • Generating reports or documents

Best Practices

  1. Keep logic in templates minimal. Complex operations should be handled in Ruby classes or helpers.
  2. Use <%= %> for outputting values and <% %> for control structures.
  3. Escape user input to prevent XSS attacks. In Rails, use <%= h(user_input) %> or <%= user_input.html_safe %> when appropriate.
  4. Consider using partials for reusable template components.
  5. Leverage Ruby String Interpolation within ERB for cleaner code.

Advanced Features

ERB offers advanced features for more complex templating needs:

  • Trim mode: Control whitespace output with ERB.new(template, trim_mode: '-')
  • Safe level: Set execution restrictions for untrusted templates
  • Custom delimiters: Change the default <% and %> tags

Integration with Ruby Frameworks

ERB is tightly integrated with Ruby web frameworks:

  • In Ruby on Rails, ERB is the default templating engine for views.
  • Sinatra supports ERB out of the box for rendering templates.
  • Many other Ruby frameworks and libraries use ERB for templating needs.

Understanding ERB is crucial for Ruby developers, especially those working on web applications. It bridges the gap between static content and dynamic Ruby code, enabling the creation of flexible and powerful templates.

Related Concepts

To deepen your understanding of Ruby and web development, explore these related topics: