module ActionView::Helpers::TagHelper - actionview-4.2.3 Documentation

# 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
TAG_PREFIXES

### 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 `]]>`.

    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]]>

    # File lib/action_view/helpers/tag_helper.rb, line 125
    def cdata_section(content)
      splitted = content.to_s.gsub(/\]\]\>/, ']]]]><![CDATA[>')
      "<![CDATA[#{splitted}]]>".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 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("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 103
    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.

    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 137
    def escape_once(html)
      ERB::Util.html_escape_once(html)
    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, symbols and BigDecimals. This may come in handy when using jQuery's HTML5-aware `.data()` 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("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;]" />

    # File lib/action_view/helpers/tag_helper.rb, line 74
    def tag(name, options = nil, open = false, escape = true)
      "<#{name}#{tag_options(options, escape) if options}#{open ? ">" : " />"}".html_safe
    end

### Private Instance Methods

boolean_tag_option(key) click to toggle source

    # File lib/action_view/helpers/tag_helper.rb, line 174
    def boolean_tag_option(key)
      %Q(#{key}="#{key}")
    end

content_tag_string(name, content, options, escape = true) click to toggle source

    # File lib/action_view/helpers/tag_helper.rb, line 143
    def content_tag_string(name, content, options, escape = true)
      tag_options = tag_options(options, escape) if options
      content     = ERB::Util.unwrapped_html_escape(content) if escape
      "<#{name}#{tag_options}>#{PRE_CONTENT_STRINGS[name.to_sym]}#{content}</#{name}>".html_safe
    end

prefix_tag_option(prefix, key, value, escape) click to toggle source

    # File lib/action_view/helpers/tag_helper.rb, line 166
    def prefix_tag_option(prefix, key, value, escape)
      key = "#{prefix}-#{key.to_s.dasherize}"
      unless value.is_a?(String) || value.is_a?(Symbol) || value.is_a?(BigDecimal)
        value = value.to_json
      end
      tag_option(key, value, escape)
    end

tag_option(key, value, escape) click to toggle source

    # File lib/action_view/helpers/tag_helper.rb, line 178
    def tag_option(key, value, escape)
      if value.is_a?(Array)
        value = escape ? safe_join(value, " ") : value.join(" ")
      else
        value = escape ? ERB::Util.unwrapped_html_escape(value) : value
      end
      %Q(#{key}="#{value}")
    end

tag_options(options, escape = true) click to toggle source

    # File lib/action_view/helpers/tag_helper.rb, line 149
    def tag_options(options, escape = true)
      return if options.blank?
      attrs = []
      options.each_pair do |key, value|
        if TAG_PREFIXES.include?(key) && value.is_a?(Hash)
          value.each_pair do |k, v|
            attrs << prefix_tag_option(key, k, v, escape)
          end
        elsif BOOLEAN_ATTRIBUTES.include?(key)
          attrs << boolean_tag_option(key) if value
        elsif !value.nil?
          attrs << tag_option(key, value, escape)
        end
      end
      " #{attrs * ' '}" unless attrs.empty?
    end