Class: ActionView::Base

Inherits:
Object show all
Includes:
Context, Helpers, ERB::Util
Defined in:
actionpack/lib/action_view/base.rb

Overview

Action View Base

Action View templates can be written in several ways. If the template file has a .erb extension then it uses a mixture of ERb (included in Ruby) and HTML. If the template file has a .builder extension then Jim Weirich’s Builder::XmlMarkup library is used.

ERB

You trigger ERB by using embeddings such as <% %>, <% -%>, and <%= %>. The <%= %> tag set is used when you want output. Consider the following loop for names:

<b>Names of all the people</b>
<% @people.each do |person| %>
  Name: <%= person.name %><br/>
<% end %>

The loop is setup in regular embedding tags <% %> and the name is written using the output embedding tag <%= %>. Note that this is not just a usage suggestion. Regular output functions like print or puts won’t work with ERB templates. So this would be wrong:

<%# WRONG %>
Hi, Mr. <% puts "Frodo" %>

If you absolutely must write from within a function use concat.

<%- and -%> suppress leading and trailing whitespace, including the trailing newline, and can be used interchangeably with <% and %>.

Using sub templates

Using sub templates allows you to sidestep tedious replication and extract common display structures in shared templates. The classic example is the use of a header and footer (even though the Action Pack-way would be to use Layouts):

<%= render "shared/header" %>
Something really specific and terrific
<%= render "shared/footer" %>

As you see, we use the output embeddings for the render methods. The render call itself will just return a string holding the result of the rendering. The output embedding writes it to the current template.

But you don’t have to restrict yourself to static includes. Templates can share variables amongst themselves by using instance variables defined using the regular embedding tags. Like this:

<% @page_title = "A Wonderful Hello" %>
<%= render "shared/header" %>

Now the header can pick up on the @page_title variable and use it for outputting a title tag:

<title><%= @page_title %></title>

Passing local variables to sub templates

You can pass local variables to sub templates by using a hash with the variable names as keys and the objects as values:

<%= render "shared/header", { :headline => "Welcome", :person => person } %>

These can now be accessed in shared/header with:

Headline: <%= headline %>
First name: <%= person.first_name %>

If you need to find out whether a certain local variable has been assigned a value in a particular render call, you need to use the following pattern:

<% if local_assigns.has_key? :headline %>
  Headline: <%= headline %>
<% end %>

Testing using defined? headline will not work. This is an implementation restriction.

Template caching

By default, Rails will compile each template to a method in order to render it. When you alter a template, Rails will check the file’s modification time and recompile it in development mode.

Builder

Builder templates are a more programmatic alternative to ERB. They are especially useful for generating XML content. An XmlMarkup object named xml is automatically made available to templates with a .builder extension.

Here are some basic examples:

xml.em("emphasized")                                 # => <em>emphasized</em>
xml.em { xml.b("emph & bold") }                      # => <em><b>emph &amp; bold</b></em>
xml.a("A Link", "href" => "http://onestepback.org")  # => <a href="http://onestepback.org">A Link</a>
xml.target("name" => "compile", "option" => "fast")  # => <target option="fast" name="compile"\>
                                                     # NOTE: order of attributes is not specified.

Any method with a block will be treated as an XML markup tag with nested markup in the block. For example, the following:

xml.div do
  xml.h1(@person.name)
  xml.p(@person.bio)
end

would produce something like:

<div>
  <h1>David Heinemeier Hansson</h1>
  <p>A product of Danish Design during the Winter of '79...</p>
</div>

A full-length RSS example actually used on Basecamp:

xml.rss("version" => "2.0", "xmlns:dc" => "http://purl.org/dc/elements/1.1/") do
  xml.channel do
    xml.title(@feed_title)
    xml.link(@url)
    xml.description "Basecamp: Recent items"
    xml.language "en-us"
    xml.ttl "40"

    @recent_items.each do |item|
      xml.item do
        xml.title(item_title(item))
        xml.description(item_description(item)) if item_description(item)
        xml.pubDate(item_pubDate(item))
        xml.guid(@person.firm..url + @recent_items.url(item))
        xml.link(@person.firm..url + @recent_items.url(item))

        xml.tag!("dc:creator", item.author_name) if item_has_creator?(item)
      end
    end
  end
end

More builder documentation can be found at builder.rubyforge.org.

Constant Summary collapse

@@field_error_proc = 
Proc.new{ |html_tag, instance| "<div class=\"field_with_errors\">#{html_tag}</div>".html_safe }
@@streaming_completion_on_exception = 
%("><script type="text/javascript">window.location = "/500.html"</script></html>)

Constants included from Helpers::TagHelper

Helpers::TagHelper::BOOLEAN_ATTRIBUTES, Helpers::TagHelper::PRE_CONTENT_STRINGS

Constants included from ActionController::RecordIdentifier

ActionController::RecordIdentifier::JOIN, ActionController::RecordIdentifier::NEW

Constants included from Helpers::NumberHelper

Helpers::NumberHelper::DECIMAL_UNITS, Helpers::NumberHelper::DEFAULT_CURRENCY_VALUES, Helpers::NumberHelper::STORAGE_UNITS

Constants included from Helpers::JavaScriptHelper

Helpers::JavaScriptHelper::JS_ESCAPE_MAP

Constants included from ERB::Util

ERB::Util::HTML_ESCAPE, ERB::Util::JSON_ESCAPE

Instance Attribute Summary collapse

Attributes included from Context

#output_buffer, #view_flow

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ActiveSupport::Concern

#append_features, extended, #included

Methods included from ActiveSupport::Autoload

#autoload, #autoload_at, #autoload_under, #autoloads, #eager_autoload, eager_autoload!

Methods included from Helpers::UrlHelper

#_routes_context, #button_to, #current_page?, #link_to, #link_to_if, #link_to_unless, #link_to_unless_current, #mail_to, #url_for, #url_options

Methods included from Helpers::TagHelper

#cdata_section, #content_tag, #escape_once, #tag

Methods included from Helpers::CaptureHelper

#capture, #content_for, #content_for?, #flush_output_buffer, #provide, #with_output_buffer

Methods included from ActionDispatch::Routing::UrlFor

#url_for, #url_options

Methods included from ActionDispatch::Routing::PolymorphicRoutes

#polymorphic_path, #polymorphic_url

Methods included from Helpers::TranslationHelper

#localize, #translate

Methods included from Helpers::TextHelper

#concat, #current_cycle, #cycle, #excerpt, #highlight, #pluralize, #reset_cycle, #safe_concat, #simple_format, #truncate, #word_wrap

Methods included from Helpers::SanitizeHelper

#sanitize, #sanitize_css, #strip_links, #strip_tags

Methods included from Helpers::RenderingHelper

#_layout_for, #render

Methods included from Helpers::RecordTagHelper

#content_tag_for, #div_for

Methods included from ActionController::RecordIdentifier

#dom_class, #dom_id

Methods included from Helpers::OutputSafetyHelper

#raw, #safe_join

Methods included from Helpers::NumberHelper

#number_to_currency, #number_to_human, #number_to_human_size, #number_to_percentage, #number_to_phone, #number_with_delimiter, #number_with_precision

Methods included from Helpers::JavaScriptHelper

#button_to_function, #escape_javascript, #javascript_cdata_section, #javascript_tag, #link_to_function

Methods included from Helpers::FormTagHelper

#button_tag, #check_box_tag, #email_field_tag, #field_set_tag, #file_field_tag, #form_tag, #hidden_field_tag, #image_submit_tag, #label_tag, #number_field_tag, #password_field_tag, #radio_button_tag, #range_field_tag, #search_field_tag, #select_tag, #submit_tag, #telephone_field_tag, #text_area_tag, #text_field_tag, #url_field_tag, #utf8_enforcer_tag

Methods included from Helpers::FormOptionsHelper

#collection_select, #grouped_collection_select, #grouped_options_for_select, #option_groups_from_collection_for_select, #options_for_select, #options_from_collection_for_select, #select, #time_zone_options_for_select, #time_zone_select

Methods included from Helpers::FormHelper

#check_box, #convert_to_model, #email_field, #fields_for, #file_field, #form_for, #hidden_field, #label, #number_field, #password_field, #radio_button, #range_field, #search_field, #telephone_field, #text_area, #text_field, #url_field

Methods included from Helpers::DebugHelper

#debug

Methods included from Helpers::DateHelper

#date_select, #datetime_select, #distance_of_time_in_words, #select_date, #select_datetime, #select_day, #select_hour, #select_minute, #select_month, #select_second, #select_time, #select_year, #time_ago_in_words, #time_select, #time_tag

Methods included from Helpers::CsrfHelper

#csrf_meta_tags

Methods included from Helpers::ControllerHelper

#assign_controller, #logger

Methods included from Helpers::CacheHelper

#cache

Methods included from Helpers::AtomFeedHelper

#atom_feed

Methods included from Helpers::AssetTagHelper

#audio_path, #audio_tag, #auto_discovery_link_tag, #favicon_link_tag, #font_path, #image_alt, #image_path, #image_tag, #video_path, #video_tag

Methods included from Helpers::AssetTagHelper::StylesheetTagHelpers

#stylesheet_link_tag, #stylesheet_path

Methods included from Helpers::AssetTagHelper::JavascriptTagHelpers

#javascript_include_tag, #javascript_path

Methods included from ActiveSupport::Benchmarkable

#benchmark, #silence

Methods included from ERB::Util

h, html_escape, j, json_escape

Methods included from Context

#_layout_for, #_prepare_context

Constructor Details

#initialize(context = nil, assigns = {}, controller = nil, formats = nil) ⇒ Base

:nodoc:



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# File 'actionpack/lib/action_view/base.rb', line 198

def initialize(context = nil, assigns = {}, controller = nil, formats = nil) #:nodoc:
  @_config = ActiveSupport::InheritableOptions.new

  # Handle all these for backwards compatibility.
  # TODO Provide a new API for AV::Base and deprecate this one.
  if context.is_a?(ActionView::Renderer)
    @view_renderer = context
  elsif
    lookup_context = context.is_a?(ActionView::LookupContext) ?
      context : ActionView::LookupContext.new(context)
    lookup_context.formats  = formats if formats
    lookup_context.prefixes = controller._prefixes if controller
    @view_renderer = ActionView::Renderer.new(lookup_context)
  end

  assign(assigns)
  assign_controller(controller)
  _prepare_context
end

Instance Attribute Details

#view_renderer ⇒ Object

Returns the value of attribute view_renderer



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# File 'actionpack/lib/action_view/base.rb', line 188

def view_renderer
  @view_renderer
end

Class Method Details

.cache_template_loading ⇒ Object 



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# File 'actionpack/lib/action_view/base.rb', line 153

def cache_template_loading
  ActionView::Resolver.caching?
end

.cache_template_loading=(value) ⇒ Object 



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# File 'actionpack/lib/action_view/base.rb', line 157

def cache_template_loading=(value)
  ActionView::Resolver.caching = value
end

.prepare(routes, helpers) ⇒ Object

This method receives routes and helpers from the controller and return a subclass ready to be used as view context.



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# File 'actionpack/lib/action_view/base.rb', line 173

def prepare(routes, helpers) #:nodoc:
  Class.new(self) do
    if routes
      include routes.url_helpers
      include routes.mounted_helpers
    end

    if helpers
      include helpers
      self.helpers = helpers
    end
  end
end

.process_view_paths(value) ⇒ Object 



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# File 'actionpack/lib/action_view/base.rb', line 161

def process_view_paths(value)
  value.is_a?(PathSet) ?
    value.dup : ActionView::PathSet.new(Array.wrap(value))
end

.xss_safe? ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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# File 'actionpack/lib/action_view/base.rb', line 167

def xss_safe? #:nodoc:
  true
end

Instance Method Details

#assign(new_assigns) ⇒ Object

:nodoc:



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# File 'actionpack/lib/action_view/base.rb', line 194

def assign(new_assigns) # :nodoc:
  @_assigns = new_assigns.each { |key, value| instance_variable_set("@#{key}", value) }
end