Class: ActionView::Base
- Defined in:
- actionview/lib/action_view/base.rb
Overview
Action View Base
Action View templates can be written in several ways. If the template file has a .erb
extension, then it uses the erubi template system which can embed Ruby into an HTML document. If the template file has a .builder
extension, then Jim Weirich’s Builder::XmlMarkup library is used.
ERB
You trigger ERB by using embeddings such as <% %>
, <% -%>
, and <%= %>
. The <%= %>
tag set is used when you want output. Consider the following loop for names:
<b>Names of all the people</b>
<% @people.each do |person| %>
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:
<%# WRONG %>
Hi, Mr. <% puts "Frodo" %>
If you absolutely must write from within a function use concat
.
When on a line that only contains whitespaces except for the tag, <% %>
suppresses leading and trailing whitespace, including the trailing newline. <% %>
and <%- -%>
are the same. Note however that <%= %>
and <%= -%>
are different: only the latter removes trailing whitespaces.
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 %>
The local variables passed to sub templates can be accessed as a hash using the local_assigns
hash. This lets you access the variables as:
Headline: <%= local_assigns[:headline] %>
This is useful in cases where you aren’t sure if the local variable has been assigned. Alternatively, you could also use defined? headline
to first check if the variable has been assigned before using it.
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 in development mode.
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 .builder
extension.
Here are some basic examples:
xml.em("emphasized") # => <em>emphasized</em>
xml.em { xml.b("emph & bold") } # => <em><b>emph & bold</b></em>
xml.a("A Link", "href" => "http://onestepback.org") # => <a href="http://onestepback.org">A Link</a>
xml.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 do
xml.h1(@person.name)
xml.p(@person.bio)
end
would produce something like:
<div>
<h1>David Heinemeier Hansson</h1>
<p>A product of Danish Design during the Winter of '79...</p>
</div>
Here is 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"
@recent_items.each do |item|
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.account.url + @recent_items.url(item))
xml.link(@person.firm.account.url + @recent_items.url(item))
xml.tag!("dc:creator", item.) if item_has_creator?(item)
end
end
end
end
For more information on Builder please consult the source code.
Direct Known Subclasses
Constant Summary collapse
- NULL =
Object.new
Constants included from Helpers::UrlHelper
Helpers::UrlHelper::BUTTON_TAG_METHOD_VERBS
Constants included from Helpers::TagHelper
Helpers::TagHelper::BOOLEAN_ATTRIBUTES, Helpers::TagHelper::PRE_CONTENT_STRINGS, Helpers::TagHelper::TAG_PREFIXES, Helpers::TagHelper::TAG_TYPES
Constants included from Helpers::JavaScriptHelper
Helpers::JavaScriptHelper::JS_ESCAPE_MAP
Constants included from RecordIdentifier
RecordIdentifier::JOIN, RecordIdentifier::NEW
Constants included from Helpers::DateHelper
Helpers::DateHelper::MINUTES_IN_QUARTER_YEAR, Helpers::DateHelper::MINUTES_IN_THREE_QUARTERS_YEAR, Helpers::DateHelper::MINUTES_IN_YEAR
Constants included from Helpers::ControllerHelper
Helpers::ControllerHelper::CONTROLLER_DELEGATES
Constants included from Helpers::AssetUrlHelper
Helpers::AssetUrlHelper::ASSET_EXTENSIONS, Helpers::AssetUrlHelper::ASSET_PUBLIC_DIRECTORIES, Helpers::AssetUrlHelper::URI_REGEXP
Constants included from ERB::Util
ERB::Util::HTML_ESCAPE, ERB::Util::HTML_ESCAPE_ONCE_REGEXP, ERB::Util::JSON_ESCAPE, ERB::Util::JSON_ESCAPE_REGEXP
Instance Attribute Summary collapse
-
#lookup_context ⇒ Object
readonly
Returns the value of attribute lookup_context.
-
#view_renderer ⇒ Object
readonly
Returns the value of attribute view_renderer.
Attributes included from Context
Class Method Summary collapse
-
.build_lookup_context(context) ⇒ Object
:stopdoc:.
- .cache_template_loading ⇒ Object
- .cache_template_loading=(value) ⇒ Object
-
.changed?(other) ⇒ Boolean
:nodoc:.
- .empty ⇒ Object
- .with_context(context, assigns = {}, controller = nil) ⇒ Object
-
.with_empty_template_cache ⇒ Object
:nodoc:.
- .with_view_paths(view_paths, assigns = {}, controller = nil) ⇒ Object
-
.xss_safe? ⇒ Boolean
:nodoc:.
Instance Method Summary collapse
- #_run(method, template, locals, buffer, &block) ⇒ Object
-
#assign(new_assigns) ⇒ Object
:nodoc:.
- #compiled_method_container ⇒ Object
- #in_rendering_context(options) ⇒ Object
-
#initialize(lookup_context = nil, assigns = {}, controller = nil, formats = NULL) ⇒ Base
constructor
:startdoc:.
Methods included from Helpers
Methods included from ActiveSupport::Concern
#append_features, #class_methods, extended, #included
Methods included from ActiveSupport::Autoload
#autoload, #autoload_at, #autoload_under, #autoloads, #eager_autoload, #eager_load!, extended
Methods included from Helpers::UrlHelper
#button_to, #current_page?, #link_to, #link_to_if, #link_to_unless, #link_to_unless_current, #mail_to, #phone_to, #sms_to, #url_for
Methods included from Helpers::TagHelper
build_tag_values, #cdata_section, #class_names, #content_tag, #escape_once, #tag
Methods included from Helpers::OutputSafetyHelper
#raw, #safe_join, #to_sentence
Methods included from Helpers::CaptureHelper
#capture, #content_for, #content_for?, #provide, #with_output_buffer
Methods included from Helpers::TranslationHelper
Methods included from Helpers::TextHelper
#concat, #current_cycle, #cycle, #excerpt, #highlight, #pluralize, #reset_cycle, #safe_concat, #simple_format, #truncate, #word_wrap
Methods included from Helpers::SanitizeHelper
#sanitize, #sanitize_css, #strip_links, #strip_tags
Methods included from Helpers::RenderingHelper
Methods included from Helpers::NumberHelper
#number_to_currency, #number_to_human, #number_to_human_size, #number_to_percentage, #number_to_phone, #number_with_delimiter, #number_with_precision
Methods included from Helpers::JavaScriptHelper
#escape_javascript, #javascript_cdata_section, #javascript_tag
Methods included from Helpers::FormTagHelper
#button_tag, #check_box_tag, #color_field_tag, #date_field_tag, #datetime_field_tag, #email_field_tag, #field_set_tag, #file_field_tag, #form_tag, #hidden_field_tag, #image_submit_tag, #label_tag, #month_field_tag, #number_field_tag, #password_field_tag, #radio_button_tag, #range_field_tag, #search_field_tag, #select_tag, #submit_tag, #telephone_field_tag, #text_area_tag, #text_field_tag, #time_field_tag, #url_field_tag, #utf8_enforcer_tag, #week_field_tag
Methods included from Helpers::FormOptionsHelper
#collection_check_boxes, #collection_radio_buttons, #collection_select, #grouped_collection_select, #grouped_options_for_select, #option_groups_from_collection_for_select, #options_for_select, #options_from_collection_for_select, #select, #time_zone_options_for_select, #time_zone_select
Methods included from Helpers::FormHelper
#check_box, #color_field, #date_field, #datetime_field, #email_field, #fields, #fields_for, #file_field, #form_for, #form_with, #hidden_field, #label, #month_field, #number_field, #password_field, #radio_button, #range_field, #search_field, #telephone_field, #text_area, #text_field, #time_field, #url_field, #week_field
Methods included from RecordIdentifier
Methods included from ModelNaming
#convert_to_model, #model_name_from_record_or_class
Methods included from Helpers::DebugHelper
Methods included from Helpers::DateHelper
#date_select, #datetime_select, #distance_of_time_in_words, #select_date, #select_datetime, #select_day, #select_hour, #select_minute, #select_month, #select_second, #select_time, #select_year, #time_ago_in_words, #time_select, #time_tag
Methods included from Helpers::CsrfHelper
Methods included from Helpers::CspHelper
Methods included from Helpers::ControllerHelper
#assign_controller, #logger, #respond_to?
Methods included from Helpers::CacheHelper
#cache, #cache_fragment_name, #cache_if, #cache_unless, #digest_path_from_template
Methods included from Helpers::AtomFeedHelper
Methods included from Helpers::AssetUrlHelper
#asset_path, #asset_url, #audio_path, #audio_url, #compute_asset_extname, #compute_asset_host, #compute_asset_path, #font_path, #font_url, #image_path, #image_url, #javascript_path, #javascript_url, #stylesheet_path, #stylesheet_url, #video_path, #video_url
Methods included from Helpers::AssetTagHelper
#audio_tag, #auto_discovery_link_tag, #favicon_link_tag, #image_tag, #javascript_include_tag, #preload_link_tag, #stylesheet_link_tag, #video_tag
Methods included from ActiveSupport::Benchmarkable
Methods included from ERB::Util
h, html_escape, html_escape_once, json_escape, unwrapped_html_escape
Methods included from Context
#_layout_for, #_prepare_context
Constructor Details
#initialize(lookup_context = nil, assigns = {}, controller = nil, formats = NULL) ⇒ Base
:startdoc:
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# File 'actionview/lib/action_view/base.rb', line 240 def initialize(lookup_context = nil, assigns = {}, controller = nil, formats = NULL) #:nodoc: @_config = ActiveSupport::InheritableOptions.new unless formats == NULL ActiveSupport::Deprecation.warn <<~eowarn.squish Passing formats to ActionView::Base.new is deprecated eowarn end case lookup_context when ActionView::LookupContext @lookup_context = lookup_context else ActiveSupport::Deprecation.warn <<~eowarn.squish ActionView::Base instances should be constructed with a lookup context, assignments, and a controller. eowarn @lookup_context = self.class.build_lookup_context(lookup_context) end @view_renderer = ActionView::Renderer.new @lookup_context @current_template = nil @cache_hit = {} assign(assigns) assign_controller(controller) _prepare_context end |
Instance Attribute Details
#lookup_context ⇒ Object (readonly)
Returns the value of attribute lookup_context
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# File 'actionview/lib/action_view/base.rb', line 198 def lookup_context @lookup_context end |
#view_renderer ⇒ Object (readonly)
Returns the value of attribute view_renderer
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# File 'actionview/lib/action_view/base.rb', line 198 def view_renderer @view_renderer end |
Class Method Details
.build_lookup_context(context) ⇒ Object
:stopdoc:
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# File 'actionview/lib/action_view/base.rb', line 209 def self.build_lookup_context(context) case context when ActionView::Renderer context.lookup_context when Array ActionView::LookupContext.new(context) when ActionView::PathSet ActionView::LookupContext.new(context) when nil ActionView::LookupContext.new([]) else raise NotImplementedError, context.class.name end end |
.cache_template_loading ⇒ Object
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# File 'actionview/lib/action_view/base.rb', line 171 def cache_template_loading ActionView::Resolver.caching? end |
.cache_template_loading=(value) ⇒ Object
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# File 'actionview/lib/action_view/base.rb', line 175 def cache_template_loading=(value) ActionView::Resolver.caching = value end |
.changed?(other) ⇒ Boolean
:nodoc:
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# File 'actionview/lib/action_view/base.rb', line 193 def changed?(other) # :nodoc: compiled_method_container != other.compiled_method_container end |
.empty ⇒ Object
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# File 'actionview/lib/action_view/base.rb', line 224 def self.empty with_view_paths([]) end |
.with_context(context, assigns = {}, controller = nil) ⇒ Object
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# File 'actionview/lib/action_view/base.rb', line 232 def self.with_context(context, assigns = {}, controller = nil) new context, assigns, controller end |
.with_empty_template_cache ⇒ Object
:nodoc:
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# File 'actionview/lib/action_view/base.rb', line 183 def with_empty_template_cache # :nodoc: subclass = Class.new(self) { # We can't implement these as self.class because subclasses will # share the same template cache as superclasses, so "changed?" won't work # correctly. define_method(:compiled_method_container) { subclass } define_singleton_method(:compiled_method_container) { subclass } } end |
.with_view_paths(view_paths, assigns = {}, controller = nil) ⇒ Object
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# File 'actionview/lib/action_view/base.rb', line 228 def self.with_view_paths(view_paths, assigns = {}, controller = nil) with_context ActionView::LookupContext.new(view_paths), assigns, controller end |
.xss_safe? ⇒ Boolean
:nodoc:
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# File 'actionview/lib/action_view/base.rb', line 179 def xss_safe? #:nodoc: true end |
Instance Method Details
#_run(method, template, locals, buffer, &block) ⇒ Object
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# File 'actionview/lib/action_view/base.rb', line 269 def _run(method, template, locals, buffer, &block) _old_output_buffer, _old_virtual_path, _old_template = @output_buffer, @virtual_path, @current_template @current_template = template @output_buffer = buffer send(method, locals, buffer, &block) ensure @output_buffer, @virtual_path, @current_template = _old_output_buffer, _old_virtual_path, _old_template end |
#assign(new_assigns) ⇒ Object
:nodoc:
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# File 'actionview/lib/action_view/base.rb', line 203 def assign(new_assigns) # :nodoc: @_assigns = new_assigns.each { |key, value| instance_variable_set("@#{key}", value) } end |
#compiled_method_container ⇒ Object
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# File 'actionview/lib/action_view/base.rb', line 278 def compiled_method_container if self.class == ActionView::Base ActiveSupport::Deprecation.warn <<~eowarn.squish ActionView::Base instances must implement `compiled_method_container` or use the class method `with_empty_template_cache` for constructing an ActionView::Base instance that has an empty cache. eowarn end self.class end |
#in_rendering_context(options) ⇒ Object
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# File 'actionview/lib/action_view/base.rb', line 290 def in_rendering_context() old_view_renderer = @view_renderer old_lookup_context = @lookup_context if !lookup_context.html_fallback_for_js && [:formats] formats = Array([:formats]) if formats == [:js] formats << :html end @lookup_context = lookup_context.with_prepended_formats(formats) @view_renderer = ActionView::Renderer.new @lookup_context end yield @view_renderer ensure @view_renderer = old_view_renderer @lookup_context = old_lookup_context end |