module Roda::RodaPlugins::Render

  1. lib/roda/plugins/render.rb

The render plugin adds support for template rendering using the tilt library. Two methods are provided for template rendering, view (which uses the layout) and render (which does not).

plugin :render

route do |r| 'foo' do
    view('foo') # renders views/foo.erb inside views/layout.erb
  end 'bar' do
    render('bar') # renders views/bar.erb

The render and view methods just return strings, they do not have side effects (unless the templates themselves have side effects). As Roda uses the routing block return value as the body of the response, in most cases you will call these methods as the last expression in a routing block to have the response body be the result of the template rendering.

Because render and view just return strings, you can call them inside templates (i.e. for subtemplates/partials), or multiple times in the same route and combine the results together:

route do |r| 'foo-bars' do
    @bars = Bar.where(:foo).map{|b| render(:bar, locals: {bar: b})}.join

You can provide options to the plugin method:

plugin :render, engine: 'haml', views: 'admin_views'

Plugin Options

The following plugin options are supported:


Set the template paths to allow. Attempts to render paths outside of this directory will raise an error. Defaults to the :views directory.


nil/false to disable template caching by default. By default, caching is disabled by default if RACK_ENV is development.


A class to use as the template cache instead of the default.


Can be set to false to turn off template path checking.


The tilt engine to use for rendering, also the default file extension for templates, defaults to 'erb'.


Use Erubi as the ERB template engine, and enable escaping by default, which makes <%= %> escape output and <%== %> not escape output. If given, sets the :escape=>true option for all template engines, which can break some non-ERB template engines. You can use a string or array of strings as the value for this option to only set the :escape=>true option for those specific template engines.


The base name of the layout file, defaults to 'layout'. This can be provided as a hash with the :template or :inline options.


The options to use when rendering the layout, if different from the default options.


The tilt options used when rendering all templates. defaults to: {outvar: '@_out_buf', default_encoding: Encoding.default_external}.


The tilt options to use per template engine. Keys are engine strings, values are hashes of template options.


The directory holding the view files, defaults to the 'views' subdirectory of the application's :root option (the process's working directory by default).

Render/View Method Options

Most of these options can be overridden at runtime by passing options to the view or render methods:

view('foo', engine: 'html.erb')
render('foo', views: 'admin_views')

There are additional options to view and render that are available at runtime:


Set to false to not cache this template, even when caching is on by default. Set to true to force caching for this template, even when the default is to not cache (e.g. when using the :template_block option).


Explicitly set the hash key to use when caching.


Only respected by view, provides the content to render inside the layout, instead of rendering a template to get the content.


Use the value given as the template code, instead of looking for template code in a file.


Hash of local variables to make available inside the template.


Use the value given as the full pathname for the file, instead of using the :views and :engine option in combination with the template name.


The object in which context to evaluate the template. By default, this is the Roda instance.


Provides the name of the template to use. This allows you pass a single options hash to the render/view method, while still allowing you to specify the template name.


Pass this block when creating the underlying template, ignored when using :inline. Disables caching of the template by default.


Provides the template class to use, inside of using Tilt or Tilt[:engine].

Here's an example of using these options:

view(inline: '<%= @foo %>')
render(path: '/path/to/template.erb')

If you pass a hash as the first argument to view or render, it should have either :template, :inline, :path, or :content (for view) as one of the keys.

Speeding Up Template Rendering

By default, determining the cache key to use for the template can be a lot of work. If you specify the :cache_key option, you can save Roda from having to do that work, which will make your application faster. However, if you do this, you need to make sure you choose a correct key.

If your application uses a unique template per path, in that the same path never uses more than one template, you can use the view_options plugin and do:

set_view_options cache_key: r.path_info

at the top of your route block. You can even do this if you do have paths that use more than one template, as long as you specify :cache_key specifically when rendering in those paths.

If you use a single layout in your application, you can also make layout rendering faster by specifying :cache_key inside the :layout_opts plugin option.


Public Class

  1. configure

Public Class methods

configure (app, opts=OPTS)

Setup default rendering options. See Render for details.

[show source]
# File lib/roda/plugins/render.rb, line 139
def self.configure(app, opts=OPTS)
  if app.opts[:render]
    orig_cache = app.opts[:render][:cache]
    opts = app.opts[:render][:orig_opts].merge(opts)
  app.opts[:render] = opts.dup
  app.opts[:render][:orig_opts] = opts

  opts = app.opts[:render]
  opts[:engine] = (opts[:engine] || "erb").dup.freeze
  opts[:views] = app.expand_path(opts[:views]||"views").freeze
  opts[:allowed_paths] ||= [opts[:views]].freeze
  opts[:allowed_paths] = opts[:allowed_paths].map{|f| app.expand_path(f, nil)}.uniq.freeze
  opts[:check_paths] = true unless opts.has_key?(:check_paths)

  unless opts.has_key?(:explicit_cache)
    opts[:explicit_cache] = if opts.fetch(:cache, true)
      ENV['RACK_ENV'] == 'development'

  opts[:cache] = orig_cache || (opts[:cache_class] || RodaCache).new

  opts[:layout_opts] = (opts[:layout_opts] || {}).dup
  opts[:layout_opts][:_is_layout] = true
  if opts[:layout_opts][:views]
    opts[:layout_opts][:views] = app.expand_path(opts[:layout_opts][:views]).freeze

  if layout = opts.fetch(:layout, true)
    opts[:layout] = true unless opts.has_key?(:layout)

    case layout
    when Hash
    when true
      opts[:layout_opts][:template] ||= 'layout'
      opts[:layout_opts][:template] = layout

  template_opts = opts[:template_opts] = (opts[:template_opts] || {}).dup
  template_opts[:outvar] ||= '@_out_buf'
  unless template_opts.has_key?(:default_encoding)
    template_opts[:default_encoding] = Encoding.default_external

  engine_opts = opts[:engine_opts] = (opts[:engine_opts] || {}).dup
  engine_opts.to_a.each do |k,v|
    engine_opts[k] = v.dup.freeze

  if escape = opts[:escape]
    require 'tilt/erubi'

    case escape
    when String, Array
      Array(escape).each do |engine|
        engine_opts[engine] = (engine_opts[engine] || {}).merge(:escape => true).freeze
      template_opts[:escape] = true