Class: ActionView::Base

Inherits:
Object show all
Includes:
CompiledTemplates, ERB::Util
Defined in:
lib/action_view/base.rb,
lib/action_view/helpers/form_helper.rb,
lib/action_view/helpers/active_record_helper.rb

Overview

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:

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

If you absolutely must write from within a function, you can use the TextHelper#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: CompiledTemplates Classes: ObjectWrapper

Constant Summary collapse

@@erb_trim_mode =

Specify trim mode for the ERB compiler. Defaults to ‘-’. See ERb documentation for suitable values.

'-'
@@cache_template_loading =

Specify whether file modification times should be checked to see if a template needs recompilation

false
@@cache_template_extensions =

Specify whether file extension lookup should be cached, and whether template base path lookup should be cached. Should be false for development environments. Defaults to true.

true
@@local_assigns_support_string_keys =

Specify whether local_assigns should be able to use string keys. Defaults to true. String keys are deprecated and will be removed shortly.

true
@@debug_rjs =

Specify whether RJS responses should be wrapped in a try/catch block that alert()s the caught exception (and then re-raises it).

false
@@erb_variable = 
'_erbout'
@@template_handlers = 
{}
@@method_names =

Maps inline templates to their method names

{}
@@compile_time =

Map method names to their compile time

{}
@@template_args =

Map method names to the names passed in local assigns so far

{}
@@inline_template_count =

Count the number of inline templates

0
@@cached_template_extension =

Maps template paths without extension to their file extension returned by pick_template_extension. If for a given path, path.ext1 and path.ext2 exist on the file system, the order of extensions used by pick_template_extension determines whether ext1 or ext2 will be stored.

{}
@@cached_base_paths =

Maps template paths / extensions to

{}
@@computed_public_paths = 
{}
@@default_template_handlers = 
nil
@@field_error_proc = 
Proc.new{ |html_tag, instance| "<div class=\"fieldWithErrors\">#{html_tag}</div>" }

Constants included from ERB::Util

ERB::Util::HTML_ESCAPE

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ERB::Util

#html_escape

Constructor Details

#initialize(view_paths = [], assigns_for_first_render = {}, controller = nil) ⇒ Base

:nodoc:



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# File 'lib/action_view/base.rb', line 269

def initialize(view_paths = [], assigns_for_first_render = {}, controller = nil)#:nodoc:
  @view_paths = view_paths.respond_to?(:find) ? view_paths.dup : [*view_paths].compact
  @assigns = assigns_for_first_render
  @assigns_added = nil
  @controller = controller
  @logger = controller && controller.logger 
end

Instance Attribute Details

#assigns ⇒ Object

Returns the value of attribute assigns.



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# File 'lib/action_view/base.rb', line 154

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 154

def base_path
  @base_path
end

#controller ⇒ Object

Returns the value of attribute controller.



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# File 'lib/action_view/base.rb', line 155

def controller
  @controller
end

#first_render ⇒ Object (readonly)

Returns the value of attribute first_render.



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

def first_render
  @first_render
end

#headers ⇒ Object (readonly)

Returns the value of attribute headers.



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

def headers
  @headers
end

#logger ⇒ Object (readonly)

Returns the value of attribute logger.



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

def logger
  @logger
end

#response ⇒ Object (readonly)

Returns the value of attribute response.



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

def response
  @response
end

#template_extension ⇒ Object

Returns the value of attribute template_extension.



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# File 'lib/action_view/base.rb', line 154

def template_extension
  @template_extension
end

#template_format ⇒ Object

symbolized version of the :format parameter of the request, or :html by default.



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# File 'lib/action_view/base.rb', line 421

def template_format
  return @template_format if @template_format
  format = controller && controller.respond_to?(:request) && controller.request.parameters[:format]
  @template_format = format.blank? ? :html : format.to_sym
end

#view_paths ⇒ Object

Returns the value of attribute view_paths.



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# File 'lib/action_view/base.rb', line 155

def view_paths
  @view_paths
end

Class Method Details

.handler_for_extension(extension) ⇒ Object 



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# File 'lib/action_view/base.rb', line 257

def self.handler_for_extension(extension)
  (extension && @@template_handlers[extension.to_sym]) || @@default_template_handlers
end

.load_helpers ⇒ Object

:nodoc:



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# File 'lib/action_view/base.rb', line 226

def self.load_helpers #:nodoc:
  Dir.entries("#{File.dirname(__FILE__)}/helpers").sort.each do |file|
    next unless file =~ /^([a-z][a-z_]*_helper).rb$/
    require "action_view/helpers/#{$1}"
    helper_module_name = $1.camelize
    if Helpers.const_defined?(helper_module_name)
      include Helpers.const_get(helper_module_name)
    end
  end
end

.register_default_template_handler(extension, klass) ⇒ Object 



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# File 'lib/action_view/base.rb', line 252

def self.register_default_template_handler(extension, klass)
  register_template_handler(extension, klass)
  @@default_template_handlers = klass
end

.register_template_handler(extension, klass) ⇒ Object

Register a class that knows how to handle template files with the given extension. This can be used to implement new template types. The constructor for the class must take the ActiveView::Base instance as a parameter, and the class must implement a #render method that takes the contents of the template to render as well as the Hash of local assigns available to the template. The #render method ought to return the rendered template as a string.



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# File 'lib/action_view/base.rb', line 244

def self.register_template_handler(extension, klass)
  @@template_handlers[extension.to_sym] = klass
end

.template_handler_extensions ⇒ Object 



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# File 'lib/action_view/base.rb', line 248

def self.template_handler_extensions
  @@template_handler_extensions ||= @@template_handlers.keys.map(&:to_s).sort
end

Instance Method Details

#append_view_path(path) ⇒ Object

Adds a view_path to the end of the view_paths array. This change affects the current request only.

@template.append_view_path("views/default")
@template.append_view_path(["views/default", "views/custom"])



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# File 'lib/action_view/base.rb', line 443

def append_view_path(path)
  @view_paths.push(*path)
end

#file_exists?(template_path) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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# File 'lib/action_view/base.rb', line 406

def file_exists?(template_path)#:nodoc:
  template_file_name, template_file_extension = path_and_extension(template_path)
  if template_file_extension
    template_exists?(template_file_name, template_file_extension)
  else
    template_exists?(template_file_name, pick_template_extension(template_path))
  end
end

#file_public?(template_path) ⇒ Boolean

Returns true is the file may be rendered implicitly.

Returns:

  • (Boolean) 


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# File 'lib/action_view/base.rb', line 416

def file_public?(template_path)#:nodoc:
  template_path.split('/').last[0,1] != '_'
end

#full_template_path(template_path, extension) ⇒ Object

Gets the full template path with base path for the given template_path and extension.

full_template_path('users/show', 'html.erb')
# => '~/rails/app/views/users/show.html.erb



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# File 'lib/action_view/base.rb', line 381

def full_template_path(template_path, extension)
  if @@cache_template_extensions
    (@@cached_base_paths[template_path] ||= {})[extension.to_s] ||= find_full_template_path(template_path, extension)
  else
    find_full_template_path(template_path, extension)
  end
end

#pick_template_extension(template_path) ⇒ Object

Gets the extension for an existing template with the given template_path. Returns the format with the extension if that template exists.

pick_template_extension('users/show')
# => 'html.erb'

pick_template_extension('users/legacy')
# => "rhtml"



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# File 'lib/action_view/base.rb', line 398

def pick_template_extension(template_path)#:nodoc:
  if @@cache_template_extensions
    (@@cached_template_extension[template_path] ||= {})[template_format] ||= find_template_extension_for(template_path)
  else
    find_template_extension_for(template_path)
  end
end

#prepend_view_path(path) ⇒ Object

Adds a view_path to the front of the view_paths array. This change affects the current request only.

@template.prepend_view_path("views/default")
@template.prepend_view_path(["views/default", "views/custom"])



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# File 'lib/action_view/base.rb', line 433

def prepend_view_path(path)
  @view_paths.unshift(*path)
end

#render(options = {}, old_local_assigns = {}, &block) ⇒ Object

Renders the template present at template_path (relative to the view_paths array). The hash in local_assigns is made available as local variables.



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# File 'lib/action_view/base.rb', line 331

def render(options = {}, old_local_assigns = {}, &block) #:nodoc:
  if options.is_a?(String)
    render_file(options, true, old_local_assigns)
  elsif options == :update
    update_page(&block)
  elsif options.is_a?(Hash)
    options = options.reverse_merge(:locals => {}, :use_full_path => true)

    if options[:layout]
      path, partial_name = partial_pieces(options.delete(:layout))

      if block_given?
        wrap_content_for_layout capture(&block) do 
          concat(render(options.merge(:partial => "#{path}/#{partial_name}")), block.binding)
        end
      else
        wrap_content_for_layout render(options) do
          render(options.merge(:partial => "#{path}/#{partial_name}"))
        end
      end
    elsif options[:file]
      render_file(options[:file], options[:use_full_path], options[:locals])
    elsif options[:partial] && options[:collection]
      render_partial_collection(options[:partial], options[:collection], options[:spacer_template], options[:locals])
    elsif options[:partial]
      render_partial(options[:partial], ActionView::Base::ObjectWrapper.new(options[:object]), options[:locals])
    elsif options[:inline]
      render_template(options[:type], options[:inline], nil, options[:locals])
    end
  end
end

#render_file(template_path, use_full_path = true, local_assigns = {}) ⇒ Object

Renders the template present at template_path. If use_full_path is set to true, it’s relative to the view_paths array, otherwise it’s absolute. The hash in local_assigns is made available as local variables.



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# File 'lib/action_view/base.rb', line 280

def render_file(template_path, use_full_path = true, local_assigns = {}) #:nodoc:
  if defined?(ActionMailer) && defined?(ActionMailer::Base) && controller.is_a?(ActionMailer::Base) && !template_path.include?("/")
    raise ActionViewError, <<-END_ERROR
Due to changes in ActionMailer, you need to provide the mailer_name along with the template name.

  render "user_mailer/signup"
  render :file => "user_mailer/signup"

If you are rendering a subtemplate, you must now use controller-like partial syntax:

  render :partial => 'signup' # no mailer_name necessary
    END_ERROR
  end
  
  @first_render ||= template_path
  template_path_without_extension, template_extension = path_and_extension(template_path)
  if use_full_path
    if template_extension
      template_file_name = full_template_path(template_path_without_extension, template_extension)
    else
      template_extension = pick_template_extension(template_path).to_s
      unless template_extension
        raise ActionViewError, "No template found for #{template_path} in #{view_paths.inspect}"
      end
      template_file_name = full_template_path(template_path, template_extension)
      template_extension = template_extension.gsub(/^.+\./, '') # strip off any formats
    end
  else
    template_file_name = template_path
  end

  template_source = nil # Don't read the source until we know that it is required

  if template_file_name.blank?
    raise ActionViewError, "Couldn't find template file for #{template_path} in #{view_paths.inspect}"
  end

  begin
    render_template(template_extension, template_source, template_file_name, local_assigns)
  rescue Exception => e
    if TemplateError === e
      e.sub_template_of(template_file_name)
      raise e
    else
      raise TemplateError.new(find_base_path_for("#{template_path_without_extension}.#{template_extension}") || view_paths.first, template_file_name, @assigns, template_source, e)
    end
  end
end

#render_template(template_extension, template, file_path = nil, local_assigns = {}) ⇒ Object

Renders the template which is given as a string as either erb or builder depending on template_extension. The hash in local_assigns is made available as local variables.



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# File 'lib/action_view/base.rb', line 365

def render_template(template_extension, template, file_path = nil, local_assigns = {}) #:nodoc:
  handler = self.class.handler_for_extension(template_extension)

  if template_handler_is_compilable?(handler)
    compile_and_render_template(handler, template, file_path, local_assigns)
  else
    template ||= read_template_file(file_path, template_extension) # Make sure that a lazyily-read template is loaded.
    delegate_render(handler, template, local_assigns)
  end
end