class ActionView::Template
Action View Template
¶ ↑
Action View Renderable
Template
for objects that respond to render_in¶ ↑
Attributes
Public Class Methods
# 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
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
# File lib/action_view/template.rb, line 168 def inspect "#<#{self.class.name} #{short_identifier} locals=#{@locals.inspect}>" end
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 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
# File lib/action_view/template.rb, line 164 def short_identifier @short_identifier ||= defined?(Rails.root) ? identifier.delete_prefix("#{Rails.root}/") : identifier end
# File lib/action_view/template.rb, line 172 def source @source.to_s end
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
# File lib/action_view/template.rb, line 160 def type @type ||= Types[format] end
Private Instance Methods
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 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
# 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
# File lib/action_view/template.rb, line 336 def identifier_method_name short_identifier.tr("^a-z_", "_") end
# File lib/action_view/template.rb, line 340 def instrument(action, &block) # :doc: ActiveSupport::Notifications.instrument("#{action}.action_view", instrument_payload, &block) end
# File lib/action_view/template.rb, line 348 def instrument_payload { virtual_path: @virtual_path, identifier: @identifier } end
# File lib/action_view/template.rb, line 344 def instrument_render_template(&block) ActiveSupport::Notifications.instrument("!render_template.action_view", instrument_payload, &block) end
# 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
# 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