Module: ActionView::Helpers::TagHelper

Overview

Provides methods to generate HTML tags programmatically both as a modern HTML5 compliant builder style and legacy XHTML compliant tags.

Defined Under Namespace

Classes: TagBuilder

Constant Summary collapse

BOOLEAN_ATTRIBUTES =
%w(allowfullscreen async autofocus autoplay checked
compact controls declare default defaultchecked
defaultmuted defaultselected defer disabled
enabled formnovalidate hidden indeterminate inert
ismap itemscope loop multiple muted nohref
noresize noshade novalidate nowrap open
pauseonexit readonly required reversed scoped
seamless selected sortable truespeed typemustmatch
visible).to_set
TAG_PREFIXES =
["aria", "data", :aria, :data].to_set.freeze
TAG_TYPES =
{}
PRE_CONTENT_STRINGS =
Hash.new { "" }

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ActiveSupport::Concern

append_features, class_methods, extended, included

Methods included from OutputSafetyHelper

#raw, #safe_join, #to_sentence

Methods included from CaptureHelper

#capture, #content_for, #content_for?, #provide, #with_output_buffer

Class Method Details

.build_tag_values(*args) ⇒ Object


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# File 'actionview/lib/action_view/helpers/tag_helper.rb', line 336

def build_tag_values(*args)
  tag_values = []

  args.each do |tag_value|
    case tag_value
    when Hash
      tag_value.each do |key, val|
        tag_values << key if val
      end
    when Array
      tag_values << build_tag_values(*tag_value).presence
    else
      tag_values << tag_value.to_s if tag_value.present?
    end
  end

  tag_values.compact.flatten
end

Instance Method Details

#cdata_section(content) ⇒ Object

Returns a CDATA section with the given content. CDATA sections are used to escape blocks of text containing characters which would otherwise be recognized as markup. CDATA sections begin with the string <![CDATA[ and end with (and may not contain) the string ]]>.

cdata_section("<hello world>")
# => <![CDATA[<hello world>]]>

cdata_section(File.read("hello_world.txt"))
# => <![CDATA[<hello from a text file]]>

cdata_section("hello]]>world")
# => <![CDATA[hello]]]]><![CDATA[>world]]>

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# File 'actionview/lib/action_view/helpers/tag_helper.rb', line 319

def cdata_section(content)
  splitted = content.to_s.gsub(/\]\]\>/, "]]]]><![CDATA[>")
  "<![CDATA[#{splitted}]]>".html_safe
end

#class_names(*args) ⇒ Object

Returns a string of class names built from args.

Examples

class_names("foo", "bar")
 # => "foo bar"
class_names({ foo: true, bar: false })
 # => "foo"
class_names(nil, false, 123, "", "foo", { bar: true })
 # => "123 foo bar"

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# File 'actionview/lib/action_view/helpers/tag_helper.rb', line 302

def class_names(*args)
  safe_join(build_tag_values(*args), " ")
end

#content_tag(name, content_or_options_with_block = nil, options = nil, escape = true, &block) ⇒ Object

Returns an HTML block tag of type name surrounding the content. Add HTML attributes by passing an attributes hash to options. Instead of passing the content as an argument, you can also use a block in which case, you pass your options as the second parameter. Set escape to false to disable attribute value escaping. Note: this is legacy syntax, see tag method description for details.

Options

The options hash can be used with attributes with no value like (disabled and readonly), which you can give a value of true in the options hash. You can use symbols or strings for the attribute names.

Examples

content_tag(:p, "Hello world!")
 # => <p>Hello world!</p>
content_tag(:div, content_tag(:p, "Hello world!"), class: "strong")
 # => <div class="strong"><p>Hello world!</p></div>
content_tag(:div, "Hello world!", class: ["strong", "highlight"])
 # => <div class="strong highlight">Hello world!</div>
content_tag(:div, "Hello world!", class: ["strong", { highlight: current_user.admin? }])
 # => <div class="strong highlight">Hello world!</div>
content_tag("select", options, multiple: true)
 # => <select multiple="multiple">...options...</select>

<%= content_tag :div, class: "strong" do -%>
  Hello world!
<% end -%>
 # => <div class="strong">Hello world!</div>

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# File 'actionview/lib/action_view/helpers/tag_helper.rb', line 284

def (name, content_or_options_with_block = nil, options = nil, escape = true, &block)
  if block_given?
    options = content_or_options_with_block if content_or_options_with_block.is_a?(Hash)
    tag_builder.(name, capture(&block), options, escape)
  else
    tag_builder.(name, content_or_options_with_block, options, escape)
  end
end

#escape_once(html) ⇒ Object

Returns an escaped version of html without affecting existing escaped entities.

escape_once("1 < 2 &amp; 3")
# => "1 &lt; 2 &amp; 3"

escape_once("&lt;&lt; Accept & Checkout")
# => "&lt;&lt; Accept &amp; Checkout"

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# File 'actionview/lib/action_view/helpers/tag_helper.rb', line 331

def escape_once(html)
  ERB::Util.html_escape_once(html)
end

#tag(name = nil, options = nil, open = false, escape = true) ⇒ Object

Returns an HTML tag.

Building HTML tags

Builds HTML5 compliant tags with a tag proxy. Every tag can be built with:

tag.<tag name>(optional content, options)

where tag name can be e.g. br, div, section, article, or any tag really.

Passing content

Tags can pass content to embed within it:

tag.h1 'All titles fit to print' # => <h1>All titles fit to print</h1>

tag.div tag.p('Hello world!')  # => <div><p>Hello world!</p></div>

Content can also be captured with a block, which is useful in templates:

<%= tag.p do %>
  The next great American novel starts here.
<% end %>
# => <p>The next great American novel starts here.</p>

Options

Use symbol keyed options to add attributes to the generated tag.

tag.section class: %w( kitties puppies )
# => <section class="kitties puppies"></section>

tag.section id: dom_id(@post)
# => <section id="<generated dom id>"></section>

Pass true for any attributes that can render with no values, like disabled and readonly.

tag.input type: 'text', disabled: true
# => <input type="text" disabled="disabled">

HTML5 data-* attributes can be set with a single data key pointing to a hash of sub-attributes.

To play nicely with JavaScript conventions, sub-attributes are dasherized.

tag.article data: { user_id: 123 }
# => <article data-user-id="123"></article>

Thus data-user-id can be accessed as dataset.userId.

Data attribute values are encoded to JSON, with the exception of strings, symbols and BigDecimals. This may come in handy when using jQuery's HTML5-aware .data() from 1.4.3.

tag.div data: { city_state: %w( Chicago IL ) }
# => <div data-city-state="[&quot;Chicago&quot;,&quot;IL&quot;]"></div>

The generated attributes are escaped by default. This can be disabled using escape_attributes.

tag.img src: 'open & shut.png'
# => <img src="open &amp; shut.png">

tag.img src: 'open & shut.png', escape_attributes: false
# => <img src="open & shut.png">

The tag builder respects HTML5 void elements if no content is passed, and omits closing tags for those elements.

# A standard element:
tag.div # => <div></div>

# A void element:
tag.br  # => <br>

Legacy syntax

The following format is for legacy syntax support. It will be deprecated in future versions of Rails.

tag(name, options = nil, open = false, escape = true)

It returns an empty HTML tag of type name which by default is XHTML compliant. Set open to true to create an open tag compatible with HTML 4.0 and below. Add HTML attributes by passing an attributes hash to options. Set escape to false to disable attribute value escaping.

Options

You can use symbols or strings for the attribute names.

Use true with boolean attributes that can render with no value, like disabled and readonly.

HTML5 data-* attributes can be set with a single data key pointing to a hash of sub-attributes.

Examples

tag("br")
# => <br />

tag("br", nil, true)
# => <br>

tag("input", type: 'text', disabled: true)
# => <input type="text" disabled="disabled" />

tag("input", type: 'text', class: ["strong", "highlight"])
# => <input class="strong highlight" type="text" />

tag("img", src: "open & shut.png")
# => <img src="open &amp; shut.png" />

tag("img", { src: "open &amp; shut.png" }, false, false)
# => <img src="open &amp; shut.png" />

tag("div", data: { name: 'Stephen', city_state: %w(Chicago IL) })
# => <div data-name="Stephen" data-city-state="[&quot;Chicago&quot;,&quot;IL&quot;]" />

tag("div", class: { highlight: current_user.admin? })
# => <div class="highlight" />

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# File 'actionview/lib/action_view/helpers/tag_helper.rb', line 248

def tag(name = nil, options = nil, open = false, escape = true)
  if name.nil?
    tag_builder
  else
    "<#{name}#{tag_builder.tag_options(options, escape) if options}#{open ? ">" : " />"}".html_safe
  end
end