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Action View Template

Namespace
Methods
C
E
H
I
L
M
N
R
S
T
Attributes
[RW] formats
[R] handler
[R] identifier
[RW] locals
[R] original_encoding
[R] source
[R] updated_at
[RW] variants
[RW] virtual_path
Class Public methods
new(source, identifier, handler, details)
# File actionview/lib/action_view/template.rb, line 130
def initialize(source, identifier, handler, details)
  format = details[:format] || (handler.default_format if handler.respond_to?(:default_format))

  @source            = source
  @identifier        = identifier
  @handler           = handler
  @compiled          = false
  @original_encoding = nil
  @locals            = details[:locals] || []
  @virtual_path      = details[:virtual_path]
  @updated_at        = details[:updated_at] || Time.now
  @formats           = Array(format).map { |f| f.respond_to?(:ref) ? f.ref : f  }
  @variants          = [details[:variant]]
  @compile_mutex     = Mutex.new
end
Instance Public methods
compile(mod)

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 actionview/lib/action_view/template.rb, line 283
      def compile(mod)
        encode!
        code = @handler.call(self)

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

        mod.module_eval(source, identifier, 0)
        if finalize_compiled_template_methods
          ObjectSpace.define_finalizer(self, Finalizer[method_name, mod])
        end
      end
compile!(view)

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

# File actionview/lib/action_view/template.rb, line 242
      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

          if view.is_a?(ActionView::CompiledTemplates)
            mod = ActionView::CompiledTemplates
          else
            mod = view.singleton_class
          end

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

          # Just discard the source if we have a virtual path. This
          # means we can get the template back.
          @source = nil if @virtual_path
          @compiled = true
        end
      end

      # 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 <tt>Encoding.default_internal</tt>.
      # In general, this means that templates will be UTF-8 inside of Rails,
      # regardless of the original source encoding.
      def compile(mod)
        encode!
        code = @handler.call(self)

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

        mod.module_eval(source, identifier, 0)
        if finalize_compiled_template_methods
          ObjectSpace.define_finalizer(self, Finalizer[method_name, mod])
        end
      end

      def handle_render_error(view, e)
        if e.is_a?(Template::Error)
          e.sub_template_of(self)
          raise e
        else
          template = self
          unless template.source
            template = refresh(view)
            template.encode!
          end
          raise Template::Error.new(template)
        end
      end

      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("".dup) { |key, code| code << "#{key} = local_assigns[:#{key}]; #{key} = #{key};" }
      end

      def method_name
        @method_name ||= begin
          m = "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}".dup
          m.tr!("-".freeze, "_".freeze)
          m
        end
      end

      def identifier_method_name
        inspect.tr("^a-z_".freeze, "_".freeze)
      end

      def instrument(action, &block) # :doc:
        ActiveSupport::Notifications.instrument("#{action}.action_view", instrument_payload, &block)
      end

      def instrument_render_template(&block)
        ActiveSupport::Notifications.instrument("!render_template.action_view".freeze, instrument_payload, &block)
      end

      def instrument_payload
        { virtual_path: @virtual_path, identifier: @identifier }
      end
  end
end
encode!()

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 actionview/lib/action_view/template.rb, line 204
    def encode!
      return 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

    private

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

          if view.is_a?(ActionView::CompiledTemplates)
            mod = ActionView::CompiledTemplates
          else
            mod = view.singleton_class
          end

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

          # Just discard the source if we have a virtual path. This
          # means we can get the template back.
          @source = nil if @virtual_path
          @compiled = true
        end
      end

      # 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 <tt>Encoding.default_internal</tt>.
      # In general, this means that templates will be UTF-8 inside of Rails,
      # regardless of the original source encoding.
      def compile(mod)
        encode!
        code = @handler.call(self)

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

        mod.module_eval(source, identifier, 0)
        if finalize_compiled_template_methods
          ObjectSpace.define_finalizer(self, Finalizer[method_name, mod])
        end
      end

      def handle_render_error(view, e)
        if e.is_a?(Template::Error)
          e.sub_template_of(self)
          raise e
        else
          template = self
          unless template.source
            template = refresh(view)
            template.encode!
          end
          raise Template::Error.new(template)
        end
      end

      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("".dup) { |key, code| code << "#{key} = local_assigns[:#{key}]; #{key} = #{key};" }
      end

      def method_name
        @method_name ||= begin
          m = "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}".dup
          m.tr!("-".freeze, "_".freeze)
          m
        end
      end

      def identifier_method_name
        inspect.tr("^a-z_".freeze, "_".freeze)
      end

      def instrument(action, &block) # :doc:
        ActiveSupport::Notifications.instrument("#{action}.action_view", instrument_payload, &block)
      end

      def instrument_render_template(&block)
        ActiveSupport::Notifications.instrument("!render_template.action_view".freeze, instrument_payload, &block)
      end

      def instrument_payload
        { virtual_path: @virtual_path, identifier: @identifier }
      end
  end
handle_render_error(view, e)
# File actionview/lib/action_view/template.rb, line 317
def handle_render_error(view, e)
  if e.is_a?(Template::Error)
    e.sub_template_of(self)
    raise e
  else
    template = self
    unless template.source
      template = refresh(view)
      template.encode!
    end
    raise Template::Error.new(template)
  end
end
identifier_method_name()
# File actionview/lib/action_view/template.rb, line 349
def identifier_method_name
  inspect.tr("^a-z_".freeze, "_".freeze)
end
inspect()
# File actionview/lib/action_view/template.rb, line 190
def inspect
  @inspect ||= defined?(Rails.root) ? identifier.sub("#{Rails.root}/", "".freeze) : identifier
end
instrument(action, &block)
# File actionview/lib/action_view/template.rb, line 353
def instrument(action, &block) # :doc:
  ActiveSupport::Notifications.instrument("#{action}.action_view", instrument_payload, &block)
end
instrument_payload()
# File actionview/lib/action_view/template.rb, line 361
def instrument_payload
  { virtual_path: @virtual_path, identifier: @identifier }
end
instrument_render_template(&block)
# File actionview/lib/action_view/template.rb, line 357
def instrument_render_template(&block)
  ActiveSupport::Notifications.instrument("!render_template.action_view".freeze, instrument_payload, &block)
end
local_assigns

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 actionview/lib/action_view/template.rb, line 106
eager_autoload do
  autoload :Error
  autoload :Handlers
  autoload :HTML
  autoload :Text
  autoload :Types
end
locals_code()
# File actionview/lib/action_view/template.rb, line 331
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("".dup) { |key, code| code << "#{key} = local_assigns[:#{key}]; #{key} = #{key};" }
end
method_name()
# File actionview/lib/action_view/template.rb, line 341
def method_name
  @method_name ||= begin
    m = "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}".dup
    m.tr!("-".freeze, "_".freeze)
    m
  end
end
refresh(view)

Receives a view object and return a template similar to self by using @virtual_path.

This method is useful if you have a template object but it does not contain its source anymore since it was already compiled. In such cases, all you need to do is to call refresh passing in the view object.

Notice this method raises an error if the template to be refreshed does not have a virtual path set (true just for inline templates).

# File actionview/lib/action_view/template.rb, line 179
def refresh(view)
  raise "A template needs to have a virtual path in order to be refreshed" unless @virtual_path
  lookup  = view.lookup_context
  pieces  = @virtual_path.split("/")
  name    = pieces.pop
  partial = !!name.sub!(/^_/, "")
  lookup.disable_cache do
    lookup.find_template(name, [ pieces.join("/") ], partial, @locals)
  end
end
render(view, locals, buffer = nil, &block)

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 actionview/lib/action_view/template.rb, line 158
def render(view, locals, buffer = nil, &block)
  instrument_render_template do
    compile!(view)
    view.send(method_name, locals, buffer, &block)
  end
rescue => e
  handle_render_error(view, e)
end
supports_streaming?()

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

# File actionview/lib/action_view/template.rb, line 148
def supports_streaming?
  handler.respond_to?(:supports_streaming?) && handler.supports_streaming?
end
type()
# File actionview/lib/action_view/template.rb, line 167
def type
  @type ||= Types[@formats.first] if @formats.first
end