Layouts and Rendering in Rails

Sending Responses

render

The Controller returns the corresponding view automatically if it is named right. Alternatively you can use render to render a different view.

def update
  @book = Book.find(params[:id])
  if @book.update(book_params)
    redirect_to(@book)
  else
    render :edit, status: :unprocessable_entity
  end
end

If the view belongs to a different controller you need to specify it:

render "products/show"

You can also render not-views:

render inline: "<% products.each do |p| %><p><%= p.name %></p><% end %>"
render plain: "OK"
render html: helpers.tag.strong("Not Found")
render json: @product
render xml: @product
render js: "alert('Hello Rails');"
render body: "raw"
render file: "#{Rails.root}/public/404.html", layout: false

Options for render

# content type
render template: "feed", content_type: "application/rss"

# different layout
render layout: "special_layout"
render layout: false

# location (redirect)
render xml: photo, location: photo_url(photo)

# set status
render status: 500
render status: :forbidden

# specify format
render formats: :xml
render formats: [:json, :xml]

# Render a specific variant
render variants: [:mobile, :desktop]
# app/views/home/index.html+mobile.erb
# app/views/home/index.html+desktop.erb

Using Layouts

Rails automatically checks if there is a layout with the same name as the controller. Else it falls back to the application.html.erb. You can also set it manually.

class ProductsController < ApplicationController
  layout "inventory"
  #...
end

redirect_to

If you want the browser to make a completely new request, you can use redirect_to

redirect_to photos_url

# there's also redirect back
redirect_back(fallback_location: root_path)
# some browsers need the fallback location

Header-Only Responses

head :bad_request

# or use some options:
head :created, location: photo_path(@photo)