# module ActionView::Helpers::TagHelper

Provides methods to generate HTML tags programmatically when you can’t use a Builder. By default, they output XHTML compliant tags.

### Constants

BOOLEAN_ATTRIBUTES
PRE_CONTENT_STRINGS

### Public Instance Methods

cdata_section(content) click to toggle source

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 `]]>`.

#### Examples¶ ↑

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

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

    # File lib/action_view/helpers/tag_helper.rb, line 112
    def cdata_section(content)
      "<![CDATA[#{content}]]>".html_safe
    end

content_tag(name, content_or_options_with_block = nil, options = nil, escape = true, &block) click to toggle source

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.

#### Options¶ ↑

The `options` hash is 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("select", options, :multiple => true)
     # => <select multiple="multiple">...options...</select>

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

    # File lib/action_view/helpers/tag_helper.rb, line 92
    def content_tag(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)
        content_tag_string(name, capture(&block), options, escape)
      else
        content_tag_string(name, content_or_options_with_block, options, escape)
      end
    end

escape_once(html) click to toggle source

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

#### Examples¶ ↑

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

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

    # File lib/action_view/helpers/tag_helper.rb, line 124
    def escape_once(html)
      ActiveSupport::Multibyte.clean(html.to_s).gsub(/[\"><]|&(?!([a-zA-Z]+|(#\d+));)/) { |special| ERB::Util::HTML_ESCAPE[special] }
    end

tag(name, options = nil, open = false, escape = true) click to toggle source

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.

To play nicely with JavaScript conventions sub-attributes are dasherized. For example, a key `user_id` would render as `data-user-id` and thus accessed as `dataset.userId`.

Values are encoded to JSON, with the exception of strings and symbols. This may come in handy when using jQuery’s HTML5-aware <tt>.data()<tt> from 1.4.3.

#### Examples¶ ↑

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

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

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

    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;]" />

    # File lib/action_view/helpers/tag_helper.rb, line 65
    def tag(name, options = nil, open = false, escape = true)
      "<#{name}#{tag_options(options, escape) if options}#{open ? ">" : " />"}".html_safe
    end