Class: ActionView::Base

Inherits:
Object
  • Object
show all
Includes:
Context, Helpers, Layouts, Partials, Rendering, ERB::Util
Defined in:
lib/action_view/base.rb

Overview

Action View Base

Action View templates can be written in three ways. If the template file has a .erb (or .rhtml) extension then it uses a mixture of ERb (included in Ruby) and HTML. If the template file has a .builder (or .rxml) extension then Jim Weirich’s Builder::XmlMarkup library is used. If the template file has a .rjs extension then it will use ActionView::Helpers::PrototypeHelper::JavaScriptGenerator.

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>
<% for person in @people %>
  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.

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 {
  xml.h1(@person.name)
  xml.p(@person.bio)
}

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"

    for item in @recent_items
      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.

JavaScriptGenerator

JavaScriptGenerator templates end in .rjs. Unlike conventional templates which are used to render the results of an action, these templates generate instructions on how to modify an already rendered page. This makes it easy to modify multiple elements on your page in one declarative Ajax response. Actions with these templates are called in the background with Ajax and make updates to the page where the request originated from.

An instance of the JavaScriptGenerator object named page is automatically made available to your template, which is implicitly wrapped in an ActionView::Helpers::PrototypeHelper#update_page block.

When an .rjs action is called with link_to_remote, the generated JavaScript is automatically evaluated. Example:

link_to_remote :url => {:action => 'delete'}

The subsequently rendered delete.rjs might look like:

page.replace_html  'sidebar', :partial => 'sidebar'
page.remove        "person-#{@person.id}"
page.visual_effect :highlight, 'user-list'

This refreshes the sidebar, removes a person element and highlights the user list.

See the ActionView::Helpers::PrototypeHelper::GeneratorMethods documentation for more details.

Defined Under Namespace

Modules: Subclasses

Constant Summary collapse

@@debug_rjs = 
false
@@field_error_proc = 
Proc.new{ |html_tag, instance| "<div class=\"field_with_errors\">#{html_tag}</div>".html_safe }

Constants included from Helpers::TagHelper

Helpers::TagHelper::BOOLEAN_ATTRIBUTES

Constants included from Helpers::ScriptaculousHelper

Helpers::ScriptaculousHelper::TOGGLE_EFFECTS

Constants included from ActionController::RecordIdentifier

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

Constants included from Helpers::PrototypeHelper

Helpers::PrototypeHelper::AJAX_OPTIONS, Helpers::PrototypeHelper::CALLBACKS

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

Instance Attribute Summary collapse

Attributes included from Context

#output_buffer

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Helpers::UrlHelper

#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, #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

#auto_link, #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::ScriptaculousHelper

#draggable_element, #draggable_element_js, #drop_receiving_element, #drop_receiving_element_js, #sortable_element, #sortable_element_js, #visual_effect

Methods included from Helpers::RecordTagHelper

#content_tag_for, #div_for

Methods included from ActionController::RecordIdentifier

#dom_class, #dom_id

Methods included from Helpers::RawOutputHelper

#raw

Methods included from Helpers::PrototypeHelper

#remote_function, #update_page, #update_page_tag

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

#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

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

#apply_form_for_options!, #check_box, #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

Methods included from Helpers::CsrfHelper

#csrf_meta_tag

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, #image_path, #image_tag, #javascript_include_tag, #javascript_path, register_javascript_expansion, register_javascript_include_default, register_stylesheet_expansion, reset_javascript_include_default, #stylesheet_link_tag, #stylesheet_path, #video_path, #video_tag

Methods included from Rendering

#_determine_template, #_render_template, #render

Methods included from Partials

#_render_partial

Methods included from Layouts

#_layout_for, #_render_layout, #find_layout

Methods included from Context

#convert_to_model

Constructor Details

#initialize(lookup_context = nil, assigns_for_first_render = {}, controller = nil, formats = nil) ⇒ Base

:nodoc:



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# File 'lib/action_view/base.rb', line 212

def initialize(lookup_context = nil, assigns_for_first_render = {}, controller = nil, formats = nil) #:nodoc:
  assign(assigns_for_first_render)
  self.helpers = self.class.helpers || Module.new

  if @_controller = controller
    @_request = controller.request if controller.respond_to?(:request)
  end

  config = controller && controller.respond_to?(:config) ? controller.config : {}
  @_config = ActiveSupport::InheritableOptions.new(config)

  @_content_for  = Hash.new { |h,k| h[k] = ActiveSupport::SafeBuffer.new }
  @_virtual_path = nil
  @output_buffer = nil

  @lookup_context = lookup_context.is_a?(ActionView::LookupContext) ?
    lookup_context : ActionView::LookupContext.new(lookup_context)
  @lookup_context.formats = formats if formats
  @controller = ActiveSupport::Deprecation::DeprecatedInstanceVariableProxy.new(self, :controller)
end

Instance Attribute Details

#assigns ⇒ Object

Returns the value of attribute assigns.



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# File 'lib/action_view/base.rb', line 183

def assigns
  @assigns
end

#base_path ⇒ Object

Returns the value of attribute base_path.



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# File 'lib/action_view/base.rb', line 183

def base_path
  @base_path
end

#lookup_context ⇒ Object

Returns the value of attribute lookup_context.



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# File 'lib/action_view/base.rb', line 183

def lookup_context
  @lookup_context
end

#template_extension ⇒ Object

Returns the value of attribute template_extension.



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# File 'lib/action_view/base.rb', line 183

def template_extension
  @template_extension
end

Class Method Details

.process_view_paths(value) ⇒ Object 



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# File 'lib/action_view/base.rb', line 203

def self.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 'lib/action_view/base.rb', line 199

def self.xss_safe? #:nodoc:
  true
end

Instance Method Details

#assign(new_assigns) ⇒ Object

:nodoc:



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# File 'lib/action_view/base.rb', line 208

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

#controller_path ⇒ Object 



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# File 'lib/action_view/base.rb', line 233

def controller_path
  @controller_path ||= controller && controller.controller_path
end

#view_context ⇒ Object

TODO: HACK FOR RJS



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# File 'lib/action_view/base.rb', line 195

def view_context
  self
end