Class: ActionView::Base

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

Overview

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

ERb

You trigger ERb by using embeddings such as <% %> and <%= %>. The difference is whether you want output or not. 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)

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 %>

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 .rxml extension.

Here are some basic examples:

xml.em("emphasized")                              # => <em>emphasized</em>
xml.em { xml.b("emp & bold") }                    # => <em><b>emph &amp; bold</b></em>
xml.a("A Link", "href"=>"http://onestepback.org") # => <a href="http://onestepback.org">A Link</a>
xm.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.

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

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

:nodoc:


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# File 'lib/action_view/base.rb', line 182

def initialize(base_path = nil, assigns_for_first_render = {}, controller = nil)#:nodoc:
  @base_path, @assigns = base_path, assigns_for_first_render
  @assigns_added = nil
  @controller = controller
  @logger = controller && controller.logger 
end

Instance Attribute Details

#assignsObject

Returns the value of attribute assigns


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# File 'lib/action_view/base.rb', line 122

def assigns
  @assigns
end

#base_pathObject

Returns the value of attribute base_path


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# File 'lib/action_view/base.rb', line 122

def base_path
  @base_path
end

#controllerObject

Returns the value of attribute controller


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# File 'lib/action_view/base.rb', line 123

def controller
  @controller
end

#first_renderObject (readonly)

Returns the value of attribute first_render


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# File 'lib/action_view/base.rb', line 121

def first_render
  @first_render
end

#flashObject (readonly)

Returns the value of attribute flash


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# File 'lib/action_view/base.rb', line 125

def flash
  @flash
end

#headersObject (readonly)

Returns the value of attribute headers


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# File 'lib/action_view/base.rb', line 125

def headers
  @headers
end

#loggerObject (readonly)

Returns the value of attribute logger


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# File 'lib/action_view/base.rb', line 125

def logger
  @logger
end

#paramsObject (readonly)

Returns the value of attribute params


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# File 'lib/action_view/base.rb', line 125

def params
  @params
end

#responseObject (readonly)

Returns the value of attribute response


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# File 'lib/action_view/base.rb', line 125

def response
  @response
end

#sessionObject (readonly)

Returns the value of attribute session


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# File 'lib/action_view/base.rb', line 125

def session
  @session
end

#template_extensionObject

Returns the value of attribute template_extension


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# File 'lib/action_view/base.rb', line 122

def template_extension
  @template_extension
end

Class Method Details

.load_helpers(helper_dir) ⇒ Object

:nodoc:


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

def self.load_helpers(helper_dir)#:nodoc:
  Dir.foreach(helper_dir) do |helper_file| 
    next unless helper_file =~ /_helper.rb$/
    require helper_dir + helper_file
    helper_module_name = helper_file.capitalize.gsub(/_([a-z])/) { |m| $1.capitalize }[0..-4]

    class_eval("include ActionView::Helpers::#{helper_module_name}") if Helpers.const_defined?(helper_module_name)
  end
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 178

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

Instance Method Details

#builder_template_exists?(template_path) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean)

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# File 'lib/action_view/base.rb', line 294

def builder_template_exists?(template_path)#:nodoc:
  template_exists?(template_path, :rxml)
end

#compile_and_render_template(extension, template = nil, file_path = nil, local_assigns = {}) ⇒ Object

Either, but not both, of template and file_path may be nil. If file_path is given, the template will only be read if it has to be compiled.


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# File 'lib/action_view/base.rb', line 256

def compile_and_render_template(extension, template = nil, file_path = nil, local_assigns = {})
  # compile the given template, if necessary
  if compile_template?(template, file_path, local_assigns)
    template ||= read_template_file(file_path, extension)
    compile_template(extension, template, file_path, local_assigns)
  end

  # Get the method name for this template and run it
  method_name = @@method_names[file_path || template]
  evaluate_assigns                                    

  local_assigns = local_assigns.symbolize_keys if @@local_assigns_support_string_keys

  send(method_name, local_assigns) do |*name|
    instance_variable_get "@content_for_#{name.first || 'layout'}"
  end
end

#delegate_template_exists?(template_path) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean)

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# File 'lib/action_view/base.rb', line 286

def delegate_template_exists?(template_path)#:nodoc:
  @@template_handlers.find { |k,| template_exists?(template_path, k) }
end

#erb_template_exists?(template_path) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean)

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# File 'lib/action_view/base.rb', line 290

def erb_template_exists?(template_path)#:nodoc:
  template_exists?(template_path, :rhtml)
end

#file_exists?(template_path) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean)

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# File 'lib/action_view/base.rb', line 298

def file_exists?(template_path)#:nodoc:
  erb_template_exists?(template_path) || builder_template_exists?(template_path) || delegate_template_exists?(template_path)
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 303

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

#pick_template_extension(template_path) ⇒ Object

:nodoc:


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# File 'lib/action_view/base.rb', line 274

def pick_template_extension(template_path)#:nodoc:
  if match = delegate_template_exists?(template_path)
    match.first
  elsif erb_template_exists?(template_path)
    'rhtml'
  elsif builder_template_exists?(template_path)
    'rxml'
  else
    raise ActionViewError, "No rhtml, rxml, or delegate template found for #{template_path}"
  end
end

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

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


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# File 'lib/action_view/base.rb', line 219

def render(options = {}, old_local_assigns = {})
  if options.is_a?(String)
    render_file(options, true, old_local_assigns)
  elsif options.is_a?(Hash)
    options[:locals] ||= {}
    options[:use_full_path] = options[:use_full_path].nil? ? true : options[:use_full_path]

    if 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] || :rhtml, 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 template_root, 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 192

def render_file(template_path, use_full_path = true, local_assigns = {})
  @first_render      = template_path if @first_render.nil?

  if use_full_path
    template_extension = pick_template_extension(template_path)
    template_file_name = full_template_path(template_path, template_extension)
  else
    template_file_name = template_path
    template_extension = template_path.split('.').last
  end

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

  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(@base_path, 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 rhtml or rxml 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 240

def render_template(template_extension, template, file_path = nil, local_assigns = {})
  if handler = @@template_handlers[template_extension]
    template ||= read_template_file(file_path, template_extension) # Make sure that a lazyily-read template is loaded.
    delegate_render(handler, template, local_assigns)
  else
    compile_and_render_template(template_extension, template, file_path, local_assigns)
  end
end