rails-views
SKILL.md
Rails Views
Quick Reference
| Pattern | Example |
|---|---|
| Output | <%= @post.title %> |
| Code | `<% @posts.each do |
| Link | <%= link_to 'Home', root_path %> |
| Form | `<%= form_with model: @post do |
| Partial | <%= render 'shared/header' %> |
| Helper | <%= truncate @post.body, length: 100 %> |
| Asset | <%= image_tag 'logo.png' %> |
ERB Basics
<%# Comment - won't be rendered %>
<% # Ruby code - executed but not displayed %>
<% if user_signed_in? %>
<p>Welcome back!</p>
<% end %>
<%= # Ruby code with output %>
<%= @post.title %>
<%= current_user.name %>
<%== # Output without HTML escaping (dangerous!) %>
<%== raw_html_content %>
<%- # Suppress whitespace before tag %>
<%- if condition -%>
<%= # Safe output (escapes HTML by default) %>
<%= user_input %> <%# Safe from XSS %>
Layouts
<%# app/views/layouts/application.html.erb %>
<!DOCTYPE html>
<html>
<head>
<title><%= content_for?(:title) ? yield(:title) : "My App" %></title>
<%= csrf_meta_tags %>
<%= csp_meta_tag %>
<%= stylesheet_link_tag "application", "data-turbo-track": "reload" %>
<%= javascript_importmap_tags %>
<%= yield :head %>
</head>
<body class="<%= controller_name %> <%= action_name %>">
<%= render 'shared/header' %>
<% flash.each do |type, message| %>
<div class="alert alert-<%= type %>">
<%= message %>
</div>
<% end %>
<main>
<%= yield %>
</main>
<%= render 'shared/footer' %>
</body>
</html>
Content For
<%# In view template %>
<% content_for :title do %>
<%= @post.title %> - My Blog
<% end %>
<% content_for :head do %>
<%= stylesheet_link_tag "posts" %>
<meta name="description" content="<%= @post.excerpt %>">
<% end %>
<%# Content here will be yielded in layout %>
<article>
<%= @post.body %>
</article>
Partials
Basic Partials
<%# Render partial %>
<%= render 'shared/header' %>
<%= render 'post' %>
<%= render partial: 'post' %>
<%# With local variables %>
<%= render 'post', post: @post %>
<%= render partial: 'post', locals: { post: @post, show_author: true } %>
<%# Partial file: app/views/shared/_header.html.erb %>
<header>
<h1>My Blog</h1>
</header>
<%# Partial file: app/views/posts/_post.html.erb %>
<article>
<h2><%= post.title %></h2>
<p><%= post.body %></p>
<% if local_assigns[:show_author] %>
<p>By <%= post.author.name %></p>
<% end %>
</article>
Collection Partials
<%# Render for each item %>
<%= render partial: 'post', collection: @posts %>
<%# Shorthand %>
<%= render @posts %>
<%# With local variable name %>
<%= render partial: 'post', collection: @posts, as: :item %>
<%# With spacer template %>
<%= render partial: 'post', collection: @posts, spacer_template: 'post_divider' %>
<%# In partial, access current index %>
<article data-index="<%= post_counter %>">
<%= post.title %>
</article>
Forms
Form Helpers
<%= form_with model: @post do |f| %>
<% if @post.errors.any? %>
<div class="errors">
<h3><%= pluralize(@post.errors.count, "error") %> prohibited this post from being saved:</h3>
<ul>
<% @post.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :title %>
<%= f.text_field :title, class: 'form-control' %>
</div>
<div class="field">
<%= f.label :body %>
<%= f.text_area :body, rows: 10, class: 'form-control' %>
</div>
<div class="field">
<%= f.label :published %>
<%= f.check_box :published %>
</div>
<div class="field">
<%= f.label :category_id %>
<%= f.collection_select :category_id, Category.all, :id, :name,
{ prompt: 'Select a category' }, { class: 'form-control' } %>
</div>
<div class="field">
<%= f.label :tag_ids %>
<%= f.collection_check_boxes :tag_ids, Tag.all, :id, :name %>
</div>
<div class="actions">
<%= f.submit "Save Post", class: 'btn btn-primary' %>
</div>
<% end %>
Form Field Types
<%= f.text_field :name %>
<%= f.text_area :description %>
<%= f.password_field :password %>
<%= f.email_field :email %>
<%= f.url_field :website %>
<%= f.number_field :age %>
<%= f.date_field :birthday %>
<%= f.datetime_field :published_at %>
<%= f.time_field :starts_at %>
<%= f.hidden_field :user_id %>
<%= f.check_box :published %>
<%= f.radio_button :status, 'active' %>
<%= f.select :category_id, Category.pluck(:name, :id) %>
<%= f.collection_select :author_id, User.all, :id, :name %>
<%= f.collection_radio_buttons :status, Status.all, :id, :name %>
<%= f.collection_check_boxes :tag_ids, Tag.all, :id, :name %>
<%= f.file_field :avatar %>
Non-Model Forms
<%= form_with url: search_path, method: :get do |f| %>
<%= f.text_field :query, placeholder: 'Search...' %>
<%= f.submit 'Search' %>
<% end %>
Links and URLs
<%# Basic link %>
<%= link_to 'Home', root_path %>
<%= link_to 'Edit', edit_post_path(@post) %>
<%= link_to 'Delete', post_path(@post), data: { turbo_method: :delete, turbo_confirm: 'Are you sure?' } %>
<%# Link to object (uses polymorphic routing) %>
<%= link_to @post.title, @post %>
<%= link_to 'Edit', [:edit, @post] %>
<%# Link with block %>
<%= link_to post_path(@post) do %>
<strong><%= @post.title %></strong>
<p><%= @post.excerpt %></p>
<% end %>
<%# Link classes and data attributes %>
<%= link_to 'Click', path, class: 'btn btn-primary', data: { action: 'click->controller#method' } %>
<%# Button to (generates a form) %>
<%= button_to 'Delete', post_path(@post), method: :delete, class: 'btn btn-danger' %>
<%# Mail to %>
<%= mail_to 'user@example.com' %>
<%= mail_to 'user@example.com', 'Contact Us', subject: 'Hello' %>
Asset Helpers
<%# Images %>
<%= image_tag 'logo.png' %>
<%= image_tag 'logo.png', alt: 'Logo', class: 'logo', size: '100x100' %>
<%= image_tag @post.cover_image_url %>
<%# Stylesheets %>
<%= stylesheet_link_tag 'application' %>
<%= stylesheet_link_tag 'posts', media: 'all' %>
<%# JavaScript %>
<%= javascript_include_tag 'application' %>
<%= javascript_importmap_tags %>
<%# Asset path %>
<%= asset_path 'image.png' %>
<%= asset_url 'image.png' %>
View Helpers
Text Helpers
<%= truncate @post.body, length: 100 %>
<%= truncate @post.body, length: 100, separator: ' ' %>
<%= simple_format @post.body %>
<%= pluralize @posts.count, 'post' %>
<%= number_to_currency 29.99 %>
<%= number_to_percentage 85.5 %>
<%= number_with_delimiter 1000000 %>
<%= number_to_human 1234567 %>
<%= time_ago_in_words @post.created_at %>
<%= distance_of_time_in_words Time.now, @post.created_at %>
Content Helpers
<%= content_tag :div, "Hello", class: 'greeting' %>
<%# Output: <div class="greeting">Hello</div> %>
<%= content_tag :div, class: 'post' do %>
<%= @post.title %>
<% end %>
<%= tag.div "Hello", class: 'greeting' %>
<%= tag.div class: 'post' do %>
<%= @post.title %>
<% end %>
Sanitization
<%# Strip all HTML tags %>
<%= strip_tags @post.html_content %>
<%# Allow specific tags %>
<%= sanitize @post.html_content, tags: %w[p br strong em] %>
<%# Escape HTML %>
<%= html_escape user_input %>
<%= h user_input %> <%# shorthand %>
Custom Helpers
# app/helpers/application_helper.rb
module ApplicationHelper
def page_title(title)
content_for(:title) { title }
content_tag(:h1, title, class: 'page-title')
end
def active_link(text, path, **options)
active = current_page?(path)
classes = options[:class].to_s
classes += ' active' if active
link_to text, path, class: classes
end
def formatted_date(date)
return 'N/A' unless date
date.strftime('%B %d, %Y')
end
def user_avatar(user, size: 50)
if user.avatar.attached?
image_tag user.avatar.variant(resize_to_limit: [size, size])
else
image_tag "default-avatar.png", size: "#{size}x#{size}"
end
end
end
<%# Using custom helpers %>
<%= page_title "My Posts" %>
<%= active_link "Home", root_path, class: 'nav-link' %>
<%= formatted_date @post.created_at %>
<%= user_avatar current_user, size: 100 %>
Turbo Frames
<%# Turbo Frame %>
<%= turbo_frame_tag "post_#{@post.id}" do %>
<%= render @post %>
<% end %>
<%# Turbo Frame with lazy loading %>
<%= turbo_frame_tag "post_#{@post.id}", src: post_path(@post), loading: :lazy do %>
Loading...
<% end %>
<%# Target a specific frame %>
<%= link_to "Edit", edit_post_path(@post), data: { turbo_frame: "post_#{@post.id}" } %>
Turbo Streams
<%# app/views/posts/create.turbo_stream.erb %>
<%= turbo_stream.prepend "posts" do %>
<%= render @post %>
<% end %>
<%= turbo_stream.update "flash" do %>
<div class="notice">Post created!</div>
<% end %>
<%# Available actions: append, prepend, replace, update, remove, before, after %>
Conditional Rendering
<% if user_signed_in? %>
<p>Welcome, <%= current_user.name %>!</p>
<%= link_to "Logout", logout_path, data: { turbo_method: :delete } %>
<% else %>
<%= link_to "Login", login_path %>
<% end %>
<% unless @posts.empty? %>
<%= render @posts %>
<% else %>
<p>No posts yet.</p>
<% end %>
<%# Ternary operator %>
<%= @post.published? ? "Published" : "Draft" %>
Loops and Iteration
<% @posts.each do |post| %>
<%= render post %>
<% end %>
<% @posts.each_with_index do |post, index| %>
<div class="post-<%= index + 1 %>">
<%= render post %>
</div>
<% end %>
<%# Check if collection is empty %>
<% if @posts.any? %>
<% @posts.each do |post| %>
<%= render post %>
<% end %>
<% else %>
<p>No posts found.</p>
<% end %>
Best Practices
- Keep views simple - Complex logic belongs in helpers or models
- Use partials for reusable components
- Use helpers for view-specific logic
- Escape user input (Rails does this by default with
<%= %>) - Use semantic HTML for accessibility
- Leverage Turbo for reactive UIs without JavaScript
- Use content_for for flexible layouts
- Keep CSS/JS out of ERB files (use asset pipeline)
- Use I18n for text content to support internationalization
- Test helpers with unit tests
Common Patterns
Conditional Class Names
<div class="<%= 'active' if @post.published? %> post">
...
</div>
<%# Better with helper %>
<div class="<%= post_classes(@post) %>">
...
</div>
# In helper
def post_classes(post)
classes = ['post']
classes << 'published' if post.published?
classes << 'featured' if post.featured?
classes.join(' ')
end
Empty State
<% if @posts.any? %>
<%= render @posts %>
<% else %>
<div class="empty-state">
<p>No posts yet.</p>
<%= link_to "Create your first post", new_post_path, class: 'btn' %>
</div>
<% end %>
References
Weekly Installs
3
Repository
shoebtamboli/ra…e_skillsGitHub Stars
4
First Seen
Mar 1, 2026
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