class ActionView::Template

Action View Template

Action View Renderable Template for objects that respond to render_in

Attributes

format[R]
handler[R]
identifier[R]
locals[R]
variable[R]
variant[R]
virtual_path[R]

Public Class Methods

new(source, identifier, handler, locals:, format: nil, variant: nil, virtual_path: nil) click to toggle source
# File lib/action_view/template.rb, line 120
def initialize(source, identifier, handler, locals:, format: nil, variant: nil, virtual_path: nil)
  @source            = source
  @identifier        = identifier
  @handler           = handler
  @compiled          = false
  @locals            = locals
  @virtual_path      = virtual_path

  @variable = if @virtual_path
    base = @virtual_path.end_with?("/") ? "" : ::File.basename(@virtual_path)
    base =~ /\A_?(.*?)(?:\.\w+)*\z/
    $1.to_sym
  end

  @format            = format
  @variant           = variant
  @compile_mutex     = Mutex.new
end

Public Instance Methods

encode!() click to toggle source

This method is responsible for properly setting the encoding of the source. Until this point, we assume that the source is BINARY data. If no additional information is supplied, we assume the encoding is the same as Encoding.default_external.

The user can also specify the encoding via a comment on the first line of the template (# encoding: NAME-OF-ENCODING). This will work with any template engine, as we process out the encoding comment before passing the source on to the template engine, leaving a blank line in its stead.

# File lib/action_view/template.rb, line 186
def encode!
  source = self.source

  return source unless source.encoding == Encoding::BINARY

  # Look for # encoding: *. If we find one, we'll encode the
  # String in that encoding, otherwise, we'll use the
  # default external encoding.
  if source.sub!(/\A#{ENCODING_FLAG}/, "")
    encoding = magic_encoding = $1
  else
    encoding = Encoding.default_external
  end

  # Tag the source with the default external encoding
  # or the encoding specified in the file
  source.force_encoding(encoding)

  # If the user didn't specify an encoding, and the handler
  # handles encodings, we simply pass the String as is to
  # the handler (with the default_external tag)
  if !magic_encoding && @handler.respond_to?(:handles_encoding?) && @handler.handles_encoding?
    source
  # Otherwise, if the String is valid in the encoding,
  # encode immediately to default_internal. This means
  # that if a handler doesn't handle encodings, it will
  # always get Strings in the default_internal
  elsif source.valid_encoding?
    source.encode!
  # Otherwise, since the String is invalid in the encoding
  # specified, raise an exception
  else
    raise WrongEncodingError.new(source, encoding)
  end
end
inspect() click to toggle source
# File lib/action_view/template.rb, line 168
def inspect
  "#<#{self.class.name} #{short_identifier} locals=#{@locals.inspect}>"
end
local_assigns() click to toggle source

Returns a hash with the defined local variables.

Given this sub template rendering:

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

You can use local_assigns in the sub templates to access the local variables:

local_assigns[:headline] # => "Welcome"
# File lib/action_view/template.rb, line 103
eager_autoload do
  autoload :Error
  autoload :RawFile
  autoload :Renderable
  autoload :Handlers
  autoload :HTML
  autoload :Inline
  autoload :Sources
  autoload :Text
  autoload :Types
end
render(view, locals, buffer = ActionView::OutputBuffer.new, add_to_stack: true, &block) click to toggle source

Render a template. If the template was not compiled yet, it is done exactly before rendering.

This method is instrumented as “!render_template.action_view”. Notice that we use a bang in this instrumentation because you don't want to consume this in production. This is only slow if it's being listened to.

# File lib/action_view/template.rb, line 151
def render(view, locals, buffer = ActionView::OutputBuffer.new, add_to_stack: true, &block)
  instrument_render_template do
    compile!(view)
    view._run(method_name, self, locals, buffer, add_to_stack: add_to_stack, &block)
  end
rescue => e
  handle_render_error(view, e)
end
short_identifier() click to toggle source
# File lib/action_view/template.rb, line 164
def short_identifier
  @short_identifier ||= defined?(Rails.root) ? identifier.delete_prefix("#{Rails.root}/") : identifier
end
source() click to toggle source
# File lib/action_view/template.rb, line 172
def source
  @source.to_s
end
supports_streaming?() click to toggle source

Returns whether the underlying handler supports streaming. If so, a streaming buffer may be passed when it starts rendering.

# File lib/action_view/template.rb, line 141
def supports_streaming?
  handler.respond_to?(:supports_streaming?) && handler.supports_streaming?
end
type() click to toggle source
# File lib/action_view/template.rb, line 160
def type
  @type ||= Types[format]
end

Private Instance Methods

compile(mod) click to toggle source

Among other things, this method is responsible for properly setting the encoding of the compiled template.

If the template engine handles encodings, we send the encoded String to the engine without further processing. This allows the template engine to support additional mechanisms for specifying the encoding. For instance, ERB supports <%# encoding: %>

Otherwise, after we figure out the correct encoding, we then encode the source into Encoding.default_internal. In general, this means that templates will be UTF-8 inside of Rails, regardless of the original source encoding.

# File lib/action_view/template.rb, line 272
      def compile(mod)
        source = encode!
        code = @handler.call(self, source)

        # Make sure that the resulting String to be eval'd is in the
        # encoding of the code
        original_source = source
        source = +<<-end_src
          def #{method_name}(local_assigns, output_buffer)
            @virtual_path = #{@virtual_path.inspect};#{locals_code};#{code}
          end
        end_src

        # Make sure the source is in the encoding of the returned code
        source.force_encoding(code.encoding)

        # In case we get back a String from a handler that is not in
        # BINARY or the default_internal, encode it to the default_internal
        source.encode!

        # Now, validate that the source we got back from the template
        # handler is valid in the default_internal. This is for handlers
        # that handle encoding but screw up
        unless source.valid_encoding?
          raise WrongEncodingError.new(source, Encoding.default_internal)
        end

        begin
          mod.module_eval(source, identifier, 0)
        rescue SyntaxError
          # Account for when code in the template is not syntactically valid; e.g. if we're using
          # ERB and the user writes <%= foo( %>, attempting to call a helper `foo` and interpolate
          # the result into the template, but missing an end parenthesis.
          raise SyntaxErrorInTemplate.new(self, original_source)
        end
      end
compile!(view) click to toggle source

Compile a template. This method ensures a template is compiled just once and removes the source after it is compiled.

# File lib/action_view/template.rb, line 238
def compile!(view)
  return if @compiled

  # Templates can be used concurrently in threaded environments
  # so compilation and any instance variable modification must
  # be synchronized
  @compile_mutex.synchronize do
    # Any thread holding this lock will be compiling the template needed
    # by the threads waiting. So re-check the @compiled flag to avoid
    # re-compilation
    return if @compiled

    mod = view.compiled_method_container

    instrument("!compile_template") do
      compile(mod)
    end

    @compiled = true
  end
end
handle_render_error(view, e) click to toggle source
# File lib/action_view/template.rb, line 309
def handle_render_error(view, e)
  if e.is_a?(Template::Error)
    e.sub_template_of(self)
    raise e
  else
    raise Template::Error.new(self)
  end
end
identifier_method_name() click to toggle source
# File lib/action_view/template.rb, line 336
def identifier_method_name
  short_identifier.tr("^a-z_", "_")
end
instrument(action, &block) click to toggle source
# File lib/action_view/template.rb, line 340
def instrument(action, &block) # :doc:
  ActiveSupport::Notifications.instrument("#{action}.action_view", instrument_payload, &block)
end
instrument_payload() click to toggle source
# File lib/action_view/template.rb, line 348
def instrument_payload
  { virtual_path: @virtual_path, identifier: @identifier }
end
instrument_render_template(&block) click to toggle source
# File lib/action_view/template.rb, line 344
def instrument_render_template(&block)
  ActiveSupport::Notifications.instrument("!render_template.action_view", instrument_payload, &block)
end
locals_code() click to toggle source
# File lib/action_view/template.rb, line 318
def locals_code
  # Only locals with valid variable names get set directly. Others will
  # still be available in local_assigns.
  locals = @locals - Module::RUBY_RESERVED_KEYWORDS
  locals = locals.grep(/\A@?(?![A-Z0-9])(?:[[:alnum:]_]|[^\0-\177])+\z/)

  # Assign for the same variable is to suppress unused variable warning
  locals.each_with_object(+"") { |key, code| code << "#{key} = local_assigns[:#{key}]; #{key} = #{key};" }
end
method_name() click to toggle source
# File lib/action_view/template.rb, line 328
def method_name
  @method_name ||= begin
    m = +"_#{identifier_method_name}__#{@identifier.hash}_#{__id__}"
    m.tr!("-", "_")
    m
  end
end