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Class: ActionView::Template

Constant Summary

Class Attribute Summary

Class Method Summary

::ActiveSupport::Autoload - Extended

autoload, autoload_at, autoload_under, eager_autoload, eager_load!

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(source, identifier, handler, locals:, format: nil, variant: nil, virtual_path: nil) ⇒ Template

[ GitHub ] 

  


# File 'actionview/lib/action_view/template.rb', line 199



def initialize(source, identifier, handler, locals:, format: nil, variant: nil, virtual_path: nil)
  @source            = source.dup
  @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
  @strict_locals     = NONE
  @strict_local_keys = nil
  @type              = nil
end


  







Class Attribute Details



  

    .mime_types_implementation=(implementation)   (writeonly)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 184



def mime_types_implementation=(implementation)
  # This method isn't thread-safe, but it's not supposed
  # to be called after initialization
  if self::Types != implementation
    remove_const(:Types)
    const_set(:Types, implementation)
  end
end


  







Instance Attribute Details



  

    #format   (readonly)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 195



attr_reader :variable, :format, :variant, :virtual_path


  








  

    #frozen_string_literal   (rw)
  

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# File 'actionview/lib/action_view/template.rb', line 180



singleton_class.attr_accessor :frozen_string_literal


  








  

    #handler   (readonly)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 194



attr_reader :identifier, :handler


  








  

    #identifier   (readonly)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 194



attr_reader :identifier, :handler


  








  

    #strict_locals?  ⇒ Boolean  (readonly)
  



  

    

Returns whether a template is using strict locals.


  





  


  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 380



def strict_locals?
  strict_locals!
end


  








  

    #supports_streaming?  ⇒ Boolean  (readonly)
  



  

    

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


  





  


  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 261



def supports_streaming?
  handler.respond_to?(:supports_streaming?) && handler.supports_streaming?
end


  








  

    #variable   (readonly)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 195



attr_reader :variable, :format, :variant, :virtual_path


  








  

    #variant   (readonly)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 195



attr_reader :variable, :format, :variant, :virtual_path


  








  

    #virtual_path   (readonly)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 195



attr_reader :variable, :format, :variant, :virtual_path


  







Instance Method Details



  

    #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.


  



  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 321



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!(LEADING_ENCODING_REGEXP, "")
    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  
  

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# File 'actionview/lib/action_view/template.rb', line 300



def inspect
  "#<#{self.class.name} #{short_identifier} locals=#{locals.inspect}>"
end


  








  

    #instrument(action, &block)   (private)
  

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# File 'actionview/lib/action_view/template.rb', line 578



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


  








  

    #local_assigns  
  



  

    

Returns a hash with the defined local variables.



Given this sub template rendering:



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




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



local_assigns[:headline] # => "Welcome"



Each key in local_assigns is available as a partial-local variable:



local_assigns[:headline] # => "Welcome"
headline                 # => "Welcome"



Since local_assigns is a ::Hash, it’s compatible with Ruby 3.1’s pattern matching assignment operator:



local_assigns => { headline:, **options }
headline                 # => "Welcome"
options                  # => {}



Pattern matching assignment also supports variable renaming:



local_assigns => { headline: title }
title                    # => "Welcome"



If a template refers to a variable that isn’t passed into the view as part of the locals: { ... } ::Hash, the template will raise an Template::Error:



<%# => raises ActionView::Template::Error %>
<% alerts.each do |alert| %>
  <p><%= alert %></p>
<% end %>




Since local_assigns returns a ::Hash instance, you can conditionally read a variable, then fall back to a default value when the key isn’t part of the locals: { ... } options:



<% local_assigns.fetch(:alerts, []).each do |alert| %>
  <p><%= alert %></p>
<% end %>




Combining Ruby 3.1’s pattern matching assignment with calls to Hash#with_defaults enables compact partial-local variable assignments:



<% local_assigns.with_defaults(alerts: []) => { headline:, alerts: } %>

<h1><%= headline %></h1>

<% alerts.each do |alert| %>
  <p><%= alert %></p>
<% end %>




By default, templates will accept any #locals as keyword arguments and make them available to local_assigns. To restrict what local_assigns a template will accept, add a locals: magic comment:



<%# locals: (headline:, alerts: []) %>

<h1><%= headline %></h1>

<% alerts.each do |alert| %>
  <p><%= alert %></p>
<% end %>




Read more about strict locals in Action View Overview in the guides.


  



  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 166



rdoc_method :method: local_assigns


  








  

    #locals  
  



  

    

The locals this template has been or will be compiled for, or nil if this is a strict locals template.


  



  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 223



def locals
  if strict_locals?
    nil
  else
    @locals
  end
end


  








  

    #render(view, locals, buffer = nil, implicit_locals: [], add_to_stack: true, &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.


  



  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 271



def render(view, locals, buffer = nil, implicit_locals: [], add_to_stack: true, &block)
  instrument_render_template do
    compile!(view)

    if strict_locals? && @strict_local_keys && !implicit_locals.empty?
      locals_to_ignore = implicit_locals - @strict_local_keys
      locals.except!(*locals_to_ignore)
    end

    if buffer
      view._run(method_name, self, locals, buffer, add_to_stack: add_to_stack, has_strict_locals: strict_locals?, &block)
      nil
    else
      result = view._run(method_name, self, locals, OutputBuffer.new, add_to_stack: add_to_stack, has_strict_locals: strict_locals?, &block)
      result.is_a?(OutputBuffer) ? result.to_s : result
    end
  end
rescue => e
  handle_render_error(view, e)
end


  








  

    #short_identifier  
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 296



def short_identifier
  @short_identifier ||= defined?(Rails.root) ? identifier.delete_prefix("#{Rails.root}/") : identifier
end


  








  

    #source  
  

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# File 'actionview/lib/action_view/template.rb', line 304



def source
  @source.to_s
end


  








  

    #strict_locals!  
  



  

    

This method is responsible for marking a template as having strict locals which means the template can only accept the locals defined in a magic comment. For example, if your template accepts the locals title and comment_count, add the following to your template file:



<%# locals: (title: "Default title", comment_count: 0) %>




Strict locals are useful for validating template arguments and for specifying defaults.


  



  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 366



def strict_locals!
  if @strict_locals == NONE
    self.source.sub!(STRICT_LOCALS_REGEX, "")
    @strict_locals = $1

    return if @strict_locals.nil? # Magic comment not found

    @strict_locals = "**nil" if @strict_locals.blank?
  end

  @strict_locals
end


  








  

    #translate_location(backtrace_location, spot)  
  



  

    

Translate an error location returned by ErrorHighlight to the correct source location inside the template.


  



  [ GitHub ]


  

  


# File 'actionview/lib/action_view/template.rb', line 251



def translate_location(backtrace_location, spot)
  if handler.respond_to?(:translate_location)
    handler.translate_location(spot, backtrace_location, encode!) || spot
  else
    spot
  end
end


  








  

    #type  
  

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# File 'actionview/lib/action_view/template.rb', line 292



def type
  @type ||= Types[format]
end